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TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

适用于汽车前灯系统的高亮度 LED 矩阵管理器

1 特性

TPS92661 器件包括一个 12 开关串联阵列（用于绕过

1

串联电路中的单个 LED）以及一个串行通信接口（通

过主微控制器进行控制和管理）。

•

12 个串联 LED 旁路开关

多点 UART 通信接口

可编程 10 位脉宽调制 (PWM) 亮度调节

板载充电泵电源轨可升至接地端以上 67 V，能够提供

LED 旁路开关栅极驱动。旁路开关的低导通电阻

(R_DS(on)) 最大限度降低了传导损耗和功耗。

–

独立的打开和关闭时间

内置相移功能

器件间同步

TPS92661 器件包含一个多点通用异步收发器

•

LED 开路/短路检测和保护

故障报告

(UART)，适用于串行通信。串联电路中各 LED 的打

开和关闭时间可单独编程。 PWM 频率可通过内部寄

存器调整，多个器件可同步为相同的频率和相位。

–

•

AEC-Q100 等级 1

散热增强型封装

–

48 引脚薄型四方扁平 (TQFP) 外露垫封装

TPS92661 器件具有 LED 开路保护以及通过串行接口

实现的 LED 开路和短路故障报告功能。

2 应用

TQFP 封装采用连通拓扑，能够在单层金属核 LED 载

板上轻松传递信号。

•

汽车前灯系统

高亮度 LED 矩阵系统

器件信息⁽¹⁾

3 说明

部件号

封装

封装尺寸（标称值）

TPS92661 器件是一款紧凑型高集成解决方案，适用

于对应用中的大阵列高亮度 LED（如，汽车前灯）进

行分流 FET 亮度调节。

TPS92661-Q1

PHP (48)

7.00mm x 7.00mm

(1) 如需了解所有可用封装，请见数据表末尾的可订购产品附录。

简化系统电路原理图

DRIVER MODULE

DC Voltage Rail

LED MODULE

VBAT

Boost

Voltage

Regulator

Buck Current

Regulator

LED12

LED1

TPS92661

LED Matrix

Manager 1

5V

3.3V / 5V

Auxiliary

Voltage

Buck

Supply

and Return

Cable

3.3V

Regulators

µC

Buck Current

Regulator

LED12

LED1

TPS92661

LED Matrix

Manager n

Rx

Tx

CAN

Xcvr

CAN

Bus

Cable

1

PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

English Data Sheet: SLUSBU2

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

1

2

3

4

5

6

特性.......................................................................... 1

8

9

Application and Implementation ........................ 38

8.1 Applications Information.......................................... 38

8.2 Design Examples .................................................... 38

Power Supply Recommendations...................... 40

9.1 General Recommendations .................................... 40

9.2 Internal Regulator.................................................... 40

9.3 Power Up and Reset............................................... 41

9.4 VIN Power Consumption......................................... 41

9.5 Initialization Set-Up ................................................. 41

应用.......................................................................... 1

说明.......................................................................... 1

修订历史记录 ........................................................... 2

Pin Configuration and Functions......................... 3

Specifications......................................................... 4

6.1 Absolute Maximum Ratings ...................................... 4

6.2 Handling Ratings....................................................... 5

6.3 Recommended Operating Conditions....................... 5

6.4 Thermal Information.................................................. 5

6.5 Electrical Characteristics........................................... 6

6.6 Typical Characteristics.............................................. 7

Detailed Description .............................................. 9

7.1 Overview ................................................................... 9

7.2 Functional Block Diagram ....................................... 10

7.3 Feature Description................................................. 10

7.4 Device Functional Modes........................................ 20

7.5 Programming........................................................... 31

7.6 Register Map........................................................... 35

10 Layout................................................................... 43

10.1 Layout Guidelines ................................................. 43

10.2 Layout Example .................................................... 43

11 器件和文档支持 ..................................................... 44

11.1 商标....................................................................... 44

11.2 静电放电警告......................................................... 44

11.3 Export Control Notice............................................ 44

11.4 术语表 ................................................................... 44

12 机械封装和可订购信息 .......................................... 45

7

4 修订历史记录

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

日期

修订版本

注释

2014 年 9 月

*

最初发布。

2

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

5 Pin Configuration and Functions

PHP (TQFP) PACKAGE

48 PINS

(TOP VIEW)

48 47 46 45 44 43 42 41 40 39 38 37

CPP

NC

LED0

NC

1

36

35

34

33

32

31

30

29

28

27

26

25

2

GND

EN

GND

EN

3

4

GND

SYNC

GND

CLK

GND

TX

GND

SYNC

GND

CLK

GND

TX

5

6

Thermal Pad

7

8

9

10

11

12

GND

RX

GND

RX

13

15 16

18 19 20

23

21 22 24

14

17

Pin Functions

I/O

DESCRIPTION

NAME

ADR0

ADR1

ADR2

NO.

22

15

16

8

I

Least significant bit (LSB) of device address. Connect to VIN or GND.

Second bit of device address. Connect to VIN or GND.

Most significant bit (MSB) of device address. Connect to VIN or GND.

System clock. This clock is provided externally (by the microcontroller unit or an external

oscillator) and is the primary clock for the device.

CLK

CPP

EN

I

29

Charge pump output. Bypass with a ceramic capacitor with a minimum value of 0.1 µF to

LED12.

1

4

Enable pins. The device is active when EN is high or in reset when EN is low. Connect to

microcontroller unit output or tie to VCC or VIN for enable at power-up.

33

3, 5, 7, 9, 11,

24, 26, 28,

30, 32, 34

GND

—

Device system ground. All pins MUST be connected for proper operation.

LED0

LED1

LED2

36

37

38

O

Connect to cathode of LED1.

Connect to anode of LED1 and cathode of LED2.

Connect to anode of LED2 and cathode of LED3.

3

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

Pin Functions (continued)

I/O

DESCRIPTION

NAME

LED3

LED4

LED5

LED6

LED7

LED8

LED9

LED10

LED11

LED12

NO.

39

40

41

42

43

44

45

46

47

48

O

Connect to anode of LED3 and cathode of LED4.

Connect to anode of LED4 and cathode of LED5.

Connect to anode of LED5 and cathode of LED6.

Connect to anode of LED6 and cathode of LED7.

Connect to anode of LED7 and cathode of LED8.

Connect to anode of LED8 and cathode of LED9.

Connect to anode of LED9 and cathode of LED10.

Connect to anode of LED10 and cathode of LED11.

Connect to anode of LED11 and cathode of LED12.

Connect to anode of LED12.

2, 17, 18, 19,

20, 21, 35

NC

—

No connection.

12

25

6

Received data pins. Connect one RX pin of first device to microcontroller unit TX output and

use second pin to connect to a RX pin of the second device. All other devices use both pins

to route the RX line through each device.

RX

I/O

Synchronization pins. Allows synchronization of multiple TPS92661 devices on the same

network. May be driven by the microcontroller unit, or one TPS92661 device may be

programmed via the serial interface to provide this pulse. Only one device should drive this

signal. May be left unconnected if not used.

SYNC

I/O

31

10

27

Transmitted data pins. Connect one TX pin of first device to microcontroller unit RX input and

use second pin to connect to a TX pin of the second device. All other devices use both pins

to route the TX line through each device. This pin requires a 100kΩ pull-up resistor.

TX

I/O

O

Output of the on-board 3.3-V LDO. This pin requires a ceramic output capacitor with a value

of 0.1 µF or greater. Tie to the VIN pin for 5-V microcontroller unit systems.

VCC

13

14

23

5-V power supply input for device. Bypass with a ceramic capacitor with a minimum value of

0.1 µF.

VIN

I

Thermal Pad

-

Connect to system GND.

6 Specifications

6.1 Absolute Maximum Ratings⁽¹⁾⁽²⁾

Over operating free-air temperature range (unless otherwise noted)

MIN

–0.3

MAX

7

UNIT

VIN, VCC to GND

CPP to GND

67

7

CPP to LED12

Input voltage

V

LEDx to GND

60

7

LEDx to LED(x-1)

SYNC, EN, CLK, TX, RX, ADR0-2 to GND

7

(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings

only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended

Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) If Military/Aerospace specified devices are required, contact the Texas Instruments Sales/Office/Distributors for availability and

specifications.

4

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

6.2 Handling Ratings

MIN

–40

MAX UNIT

T_stg

Storage temperature range

Electrostatic discharge

150

°C

(1)

Human body model (HBM), per AEC Q100-002

Charged device model (CDM), per

AEC Q100-011

–2000

2000

V_(ESD)

V

ALL Pins

–750

750

(1) AEC Q100-002 indicates HBM stressing is done in accordance with the ANSI/ESDA/JEDEC JS-001 specification.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)

MIN

NOM

MAX

UNIT

V

V_IN

V_I

Supply input voltage range

Input voltage range per channel

Output current range

CLK frequency⁽¹⁾

4.5

5.5

5.0

LEDx to LED(x-1)

V

I_O

Thermally Limited

A

f_CLK

D_CLK

t_EW

t_ESS

t_SW

0.1

40%

16

MHz

CLK duty cycle

60%

EN input pulse width low

EN setup to serial start

SYNC input pulse width

50

ns

s

24/f_CLK

1/f_CLK

s

V_VCC

0.3 V

+

V_IH

V_IL

High-level input voltage

Low-level input voltage

1.9

V

GND –

0.3 V

0.8

T_A

T_J

Ambient temperature

Junction temperature

–40

125

150

°C

(1) Minimum f_clkis applicable only when CKWEN bit is set. f_clkdown to 0Hz is possible when bit is not set.

6.4 Thermal Information

TPS92661

TQFP

48 pins

25.7

THERMAL METRIC⁽¹⁾

UNITS

R_θJA

Junction-to-ambient thermal resistance

Junction-to-case (top) thermal resistance

Junction-to-board thermal resistance

R_θJC(top)

R_θJB

10.5

6.1

°C/W

ψ_JT

Junction-to-top characterization parameter

Junction-to-board characterization parameter

Junction-to-case (bottom) thermal resistance

0.2

ψ_JB

6.0

R_θJC(bot)

0.3

(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

5

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

6.5 Electrical Characteristics

Limits apply over operating junction temperature range –40°C ≤ T_J≤ +150°C. Typical values represent the most likely

parametric norm at T_J= 25°C. Unless otherwise noted, V_IN= 5 V. For digital outputs, C_LOAD= 20 pF.

UNIT

S

PARAMETER

CONDITIONS

MIN

TYP

MAX

GENERAL

I_VIN-OP

V_IN-UVT

V_CC-REG

I_VCC-LIM

V_CPP

Input operating bias current

VIN internal POR threshold

Regulated VCC voltage

No switching

1

mA

V

VIN rising

4.5

3.5

0 mA ≤ I_VCC≤ 5 mA

3.1

1.3

3.3

10

V

VCC current limit

mA

V

Charge pump operating voltage

Charge pump oscillator frequency

V_VIN= 5 V, V_SW= 0 V – 60 V

6.2

2.3

f_CPP

3.3 MHz

LED MATRIX SWITCHES

(1)

R_DS(on)

R_ALL(on)

I_DS(off)

V_TH-S

LED switch on-resistance

All switches on-resistance

225

mΩ

Measured LED12 - LED0

1800

3400 mΩ

OFF state switch leakage current

LED short threshold voltage

LED OPEN threshold voltage

50

1.4

6.9

µA

V

V_SW= 0 V – 60 V

0.52

5

V_TH-O

6

V

LED OPEN detection and correction

delay

t_TO-O

50

150

5

ns

t_REP

LED fault reporting delay

µs

t_RISE(LEDx)

t_FALL(LEDx)

LEDx drain voltage rise time⁽²⁾

LEDx drain voltage fall time⁽²⁾

I_LED= 800 mA

2

DIGITAL SPECIFICATIONS

V_IH-TH

V_IL-TH

V_OH

High-level input voltage threshold

1.9

V

Low-level input voltage threshold

High-level output voltage

0.8

I_SOURCE= 2 mA, V_VCC= 4.0 V

I_SINK= 2 mA, V_VCC= 4.5 V

4.27

V_OL

Low-level output voltage

0.23

Output short circuit current (source or

sink)

I_OS

V_VCC= 4.5 V

42

mA

R_SP

t_WD-TO

t_TO

Internal SYNC pull-down

100

kΩ

µs

ns

CLK watchdog timeout

32/f_CPP

80

CLK rise to TX output valid⁽²⁾

CLK rise to TX output tri-state⁽²⁾

t_TZ

80

(1) Single channel on-resitance (R_DS(on)) measurement includes internal bond wires. All switches on-resistance (R_ALL(on)) should be used for

all power calculations. See Internal Switch Resistance for details.

(2) Specified by design. Not production tested.

6

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

6.6 Typical Characteristics

T_A= 25°C free air unless otherwise specified

6

5.4

4.8

4.2

3.6

3

5.4

4.8

4.2

3.6

3

f_PWM= 732 Hz

f_PWM= 146 Hz

2.4

1.8

1.2

0.6

0

2.4

1.8

1.2

0.6

0

f_PWM= 4185 Hz

f_PWM= 523 Hz

f_PWM= 209 Hz

-40 -25 -10

5

20 35 50 65 80 95 110 125

Ambient Temperature (°C)

-40 -25 -10

5

20 35 50 65 80 95 110 125

Ambient Temperature (°C)

D010

D011

V_VIN= 5.5 V

f_CLK= 6 MHz

V_VIN= 5.5 V

f_CLK= 8.57 MHz

Figure 1. Input Voltage Current vs Temperature

Figure 2. Input Voltage Current Draw vs

Temperature

6

5.4

4.8

4.2

3.6

3

1.35

1.3

1.25

1.2

f_PWM= 916 Hz

f_PWM= 229 Hz

2.4

1.8

1.2

0.6

0

1.15

1.1

-40 -25 -10

5

20 35 50 65 80 95 110 125

Ambient Temperature (°C)

-40 -21

-2

17

36

55

74

93 112 131 150

Junction Temperature (^oC)

D012

D015

V_VIN= 5.5 V

f_CLK= 15 MHz

Figure 3. Input Voltage Current Draw vs

Temperature

Figure 4. Input Operating Bias Current, Non-

Switching vs. Junction Temperature

3.35

2.8

I_VCC= No Load

I_VCC= 5 mA

3.34

3.33

3.32

3.31

3.3

2.6

2.4

2.2

2

3.29

3.28

3.27

3.26

3.25

1.8

1.6

1.4

-40 -21

-2

17

36

55

74

93 112 131 150

-40 -21

-2

17

36

55

74

93 112 131 150

Junction Temperature (^oC)

D016

D017

Figure 5. Regulated VCC Voltage vs Junction

Temperature

Figure 6. All Switches On-Resistance vs Junction

Temperature

7

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

Typical Characteristics (continued)

T_A= 25°C free air unless otherwise specified

2.3

1.4

1.3

1.2

1.1

1

6.8

V_TH-S(Short)

V_TH-O(Open)

2.28

2.26

2.24

2.22

2.2

6.6

6.4

6.2

6

2.18

2.16

2.14

2.12

2.1

0.9

0.8

0.7

5.8

5.6

5.4

-40 -21

-2

17

36

55

74

93 112 131 150

-40 -21

-2

17

36

55

74

93 112 131 150

Junction Temperature (^oC)

D018

D019

Figure 7. Charge Pump Oscillator Frequency vs

Junction Temperature

Figure 8. Channel Open and Short Protection

Thresholds vs Junction Temperature

8

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

7 Detailed Description

7.1 Overview

The TPS92661 lighting matrix manager (LMM) device, in conjunction with a buck switching current regulator,

enables a fully dynamic matrix beam solution where each LED can be individually controlled. This type of control

of an LED array is ideally suited for dynamic headlight applications where adaptive beam forming requires pixel

level control of the array.

The TPS92661 device configures 12 series connected low voltage switches (MOSFETs) that can float up to 67 V

above ground potential. Each switch connects in parallel to one LED, thereby creating individual shunt paths

across each LED of a series string of 12 LEDs. LED strings with fewer LEDs can be used, however the unused

channels should be physically shorted externally to reduce unnecessary internal power consumption.

Each switch has an individual driver, overvoltage protection circuit and diagnostics circuit referenced to the

source of that switch. This configuration allows for fully dynamic operation with the switches above it and below

it. The device monitors overvoltage conditions on each switch and automatically protects them in the event of an

open LED connection. The device detects open LED conditions as well as shorted LED conditions and reports

them through the fault reporting network.

All twelve internal bypass switches can be individually pulse width modulated (PWM) at a programmed frequency

and duty cycle. This PWM dimming topology provides Inherent phase shifting capability. In addition, the switch

transitions during PWM dimming are slew rate limited to mitigate any EMI concerns due to the di/dt and dv/dt of

the switching action.

The TPS92661 device also provides multi-drop UART communications capability between a host MCU and up to

8 slave TPS92661 devices. The UART receives data corresponding to the desired PWM information for all 12

internal switches. In addition, it can send back fault and other diagnostic data to the host MCU. Hardware

connections on the three address pins allows addressing of the eight devices.

An internal regulator accepts the 5-V power supply input for the TPS92661 device and generates a 3.3-V

regulated output for the I/O buffers used in the internal UART. The internal regulator can be bypassed by

shorting VIN to VCC if 5-V communication is desired.

The combination of features in the TPS92661 device provides the ideal interface for individual control of high

current LED arrays. The Figure 27 shows a dynamic headlight application using multiple TPS92661 devices. The

electronic control unit (ECU), usually attached to the outside of the headlight, contains the master MCU, a boost

pre-regulator stage that takes the variable battery voltage and steps it up to a stable DC voltage rail. The

application includes multiple channels of buck current regulators to provide a stable current through each series

string of 12 high brightness LEDs. The TPS92661 device should reside on the LED load board where it is as

close as possible to the LEDs to which it directly connects.

This location has two major benefits.

•

The close proximity minimizes distributed inductance and parasitic capacitance associated with the cable

connection between ECU board and LED load board. When PWM dimming with a parallel shunt FET, locating

the switch close to the LED prevents large ringing during each transition.

•

The close proximity offers better thermal connection

Ultimately, the TPS92661 device enables an optimal partition for a flexible, high performing dynamic headlight

system.

9

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

7.2 Functional Block Diagram

CPP

Charge Pump

VIN

CPP

LED12

LED11

VIN

Level

Shifters

Driver with LED

Fault Detection

Linear

Regulator

VCC

CPP

GND

Level

Shifters

Driver with LED

Fault Detection

Regulators

Logic

and

LED10

Registers

EN

ADR2

ADR1

ADR0

SYNC

CPP

LED2

LED1

Level

Shifters

Driver with LED

Fault Detection

CLK

CPP

RX

TX

Level

Shifters

Driver with LED

Fault Detection

LED0

Switch Array

Communications

VCC

7.3 Feature Description

7.3.1 Controlling the Internal LED Bypass Switches

The TPS92661 device (LED Matrix Manager) consists of 12 series connected bypass switches between

terminals LED12 and LED0. Each bypass switch, when driven to an off state, allows the string current to flow

through the corresponding parallel-connected LED, turning the LED on. Conversely, driving the bypass switch to

an on state shunts the current through the bypass switch and turns the LED off.

10

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

Feature Description (continued)

7.3.2 Internal Switch Resistance

Each single switch (connected between LED_nand LED_n–1) has a measurable typical R_DS(on)value of 225 mΩ.

This measurement includes the actual on-resistance (R_DS(on)) of the switch and the resistance of the two

internally connected bond wires. When multiple series switches are on, the effective resistance is not simply the

number of channels multiplied by 225 mΩ because there are not two conducting bond wires for every series-

connected switch. For this reason the all-switches on-resistance (R_ALL(on)) is specified in the Electrical

Characteristics table. This value includes the twelve R_DS(on)on-resistances and the resistance of the bond wires

at each end of the series connected switches.

The dominant power loss mechanism In the TPS92661 device, is I²R loss through the switches. Other power

loss sources are always less than 50 mW. When calculating the power dissipation of the TPS92661 device

switches, use Equation 1 for the best estimation of this power loss.

n

æ

ö

R_{DS on}

= R_{ALL on}

´

max

= 238 mW ´n

ç

÷

x _channels

( )(

)

( )(

)

12

è

ø

where

•

n is the number of channels

(1)

See the 6 LED, 1.5-A Application section for a sample calculation.

7.3.3 PWM Dimming

The TPS92661 device provides 10-bit PWM dimming of each individual LED. The LED turn-on and turn-off times

are separately programmed for each LED. The LEDxON registers and LEDxOFF registers (where x = 1 to 12)

determine the LED turn-on and turn-off times, respectively, within the PWM dimming period. Phase shifting can

be accomplished by staggering the LEDxON times or LEDxOFF times. The 10-bit internal PWM Period Counter

(TCNT) is compared against the LEDxON and LEDxOFF values.

When TCNT reaches the programmed LEDxON value for a given LED, the corresponding bypass switch is

turned off to force current through the LED. Similarly, when TCNT reaches the programmed LEDxOFF value, the

bypass switch is turned on to turn off the LED. TCNT counts continuously from 0 to 1023 and returns to 0 again.

The LED PWM dimming period equals 1024 times the internally divided, programmable PWM clock period.

Figure 9 shows an example of LED PWM using values of LEDxON = 250 and LEDxOFF = 800.

1023

LEDxOFF

800

LEDxON

250

TCNT

0

LEDx

current

Time

Figure 9. LED PWM Example

Because the LEDxON and LEDxOFF times are completely programmable, this allows the system flexibility to

phase shift the leading edge (LED On), the trailing edge (LED Off), or double-edge PWM.

The comparison circuitry consists of a digital comparator, along with an AND gate to allow that particular

comparison to propagate to the LED switch. The TCNT counter value is continuously compared against the value

programmed into the LED On/Off registers. The ENON bit that corresponds to that particular LED determines

whether or not that comparison has any effect at the LED. The logic is represented in Figure 10.

11

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

Feature Description (continued)

LEDX Pin

A==B

TCNT[9:0]

LEDx Turn Off

A

B

LEDxOFF[9:0]

S

R

Q

ENOFF[x]

TCNT[9:0]

A

B

LEDX-1 Pin

LEDxON[9:0]

LEDx Turn On

ENON[x]

Figure 10. PWM Dimming Control Logic

7.3.4 PWM Clock

The PWM clock that drives TCNT is a divided-down version of the CLK input. The divider is programmed by

writing to the PWM clock divider register (PCKDIV). The divider comprises two dividers in series: a power-of-2

clock divider followed by a decimal count divider (see Figure 11 and PWM Clock Divider Register (PCKDIV) for

PCKDIV bitmap). Upon power-up, the PWM clock divider is programmed to a divisor value of 16.

LMM

PCKDIV

TCNT

10-bit

Counter

Power-of-Two

Divider

Decimal

Divider

CLK

Figure 11. PWM Clock Divider

7.3.5 PWM Synchronization

Upon power-up, the TCNT counter is reset to 0. The TCNT counter is clocked by the internal PWM clock. In

order to correctly synchronize multiple TPS92661 devices on the same network, two conditions must be met:

•

All TPS92661 devices must be clocked by the same clock on the CLK terminal.

All TPS92661 devices must be programmed with the same PWM clock dividers (PCKDIV).

Assuming that these conditions are met, the TPS92661 devices may be synchronized by either of two methods:

1. As shown in Figure 12, the TPS92661 device includes a synchronization input/output (SYNC) and a

synchronization master bit (SCMAST) in the system configuration register (SYSCFG). If SCMAST is set to 1,

the TPS92661 device drives the SYNC terminal. The TPS92661 device generates a high pulse that is one-

half of a PWM period on SYNC when TCNT and the PWM clock divider are about to roll over to 0. This

SYNC signal can be fed to other TPS92661 devices. In other words, either the MCU can drive SYNC, or only

one TPS92661 device should have SCMAST set to 1. The rest of the TPS92661 devices on the network

must have SCMAST set to 0. If SCMAST is set to 0 (the default value), a low-to-high transition on SYNC at

least one CLK cycle resets both TCNT and the PWM clock divider to 0 after internally synchronizing to the

rising edge of CLK. SYNC is a feed-through signal that may be tied to the next TPS92661 device in order to

synchronize multiple TPS92661 devices with respect to each other.

NOTE

In order to prevent bus contention, ensure that the network design includes only one

synchronization master.

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Feature Description (continued)

2. The TCNT counter and PWM clock divider can both be reset to 0 at any time by issuing a broadcast write

synchronization command. Due to UART bit sampling variability, the synchronization is guaranteed to be

within only 16 CLK cycles between TPS92661 devices.

SYSCFG

SCMAST

SYNC

Rising Edge

Detector

SYNC CMD Pulse

CLR

PWM Clock Divider and TCNT

CLK

Figure 12. PWM Synchronization

Figure 13 and Figure 14 show an example of two non-synchronized TPS92661 devices and two synchronized

devices respectively. In this example all twelve channels on each device are programmed with LED_ON= 0 and

LED_OFF= 128. In the non-synchronized example TCNT = 0 occurs at two different places in time. By using the

SYNC function, TCNT = 0 occurs simultaneously for both devices.

CH1: (Dark Blue) Device 1 LED string voltage

CH2: (Light Blue) Device 2 LED string voltage

CH3: (Pink) SYNC signal as generated by 1 device

CH1: (Dark Blue) Device 1 LED string voltage

CH2: (Light Blue) Device 2 LED string voltage

CH3: (Pink) SYNC signal as generated by 1 device

Figure 13. Non-Synchronized TPS92661 Devices

Figure 14. Actively Synchronized TPS92661 Devices

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Feature Description (continued)

7.3.6 Switch Slew Control

The gate drive control of each series switch slows the rate of change of current through the device. This control

eases EMI requirements and aids in the system operation. The switching transition controls the current through

the switch at each edge to approximately 800 mA/2 µs. The internal circuitry of the device controls the slew rate.

The user cannot change the slew rate. The rise and fall slew rates are matched to ensure accurate

representation of the PWM duty cycle. These slew rates assume no LED string capacitance.

LED_n T_ON

I_{LED_n}

Slope: 800mA/2µsec

Typical

Figure 15. TPS92661 Slew Rate Control

7.3.7 Effect of Phase Shifting LED Duty Cycles

Figure 16 and Figure 17 show the effective system input current (CH4, green trace) and V_(LED12-LED0)string

voltage (CH1, blue trace) for various phase shift settings. The results illustrate the advantages of adjusting the

phase shift value to minimize the variation in input current. Figure 16 illustrates a zero phase shift condition by

setting all twelve LEDxON values to zero and all twelve LEDxOFF values to 128. Figure 17 illustrates optimal

phase shifting where all twelve LEDxON values are spaced by a count of 85 (0, 85, 170, 235, ...). The input

current variation is greatly reduced with optimal phase shifting as all twelve channels do not draw current from

the input simultaneously. This reduces demands on the energy storage capacitance at the system input.

No Phase Shift

Duty Cycle = 128/1024

Phase Shift = 85

Duty Cycle = 128/1024

Figure 16. Single Channel,

Figure 17. Single Channel

7.3.8 LED Fault Detection and Protection

Each individual bypass switch is driven by a floating driver which is powered by the charge pump (see Functional

Block Diagram). The steady floating driver supply also enables continuous protection and monitoring of LED

open and short events.

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Feature Description (continued)

In the event of an OPEN LED failure, an internal comparator monitors the drain-to-source voltage of the internal

switch. If the voltage exceeds V_TH-O(typical 6 V) the device overrides the switch-off signal and turns on the

switch. This action maintains current flow in the rest of the LED string in the presence of a faulty or damaged

LED and protects the internal switch. The internal latch holds this state until a subsequent on and off cycle at

which time the switch attempts to turn off again, and the condition is re-evaluated. The protection circuit also sets

the corresponding bit in the FAULT register described in the Diagnostic Registers section . The controller can poll

this register to determine whether a fault has occurred.

When the device resets a FAULT bit in the register array by writing the bit back to zero, it then clears the latch

and re-enables the OPEN switching transition of the corresponding LED. This feature allows the controller to

perform multiple checks of the LED fault so that false LED faults can be filtered via software.

Similar to LED open detection, an LED short is detected via monitoring the drain-to-source voltage of the internal

switch. If the voltage does not exceed the V_TH-Sthreshold by the end of the PWM cycle, the same fault register

bit is set. Both short and open cases are handled by the same register as each case has the equivalent

outcome, which is that the channel is bypassed. (see Figure 18)

Floating

Gate Driver

Supply

LED_n+1

+

R

Q

R is

dominant

Ref OV

S

Gate

Driver

Ref Short

LED_n

Sync and

Level Shift

Into Fault

Register

Gate Driver

Level Shift

Circuitry

Figure 18. Fault Detection Block

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Feature Description (continued)

7.3.8.1 Fault Reporting and Timing

Fault detection and protection occur immediately and are independent of any internal clock. The device detects

an overvoltage condition when the channel voltage rises to the OVP (overvoltage protection) comparator

threshold. The channel switch is then latched ON with a delay of approximately 50 ns (typical). This detection

generates a fault signal that is sent to the internal fault register when TCNT = LEDxOFF where it can be polled

by the user. Similarly, the short detection fault signal is sent with the same timing. The Diagnostic Registers are

updated in a maximum time of one full PWM period (a PWM count of 1024). Due to internal propagation delays

the LED On-time count must conform to Equation 2 for accurate fault reporting. For typical applications this may

require fault reporting to be ignored at duty cycles less than 1%.

æ

ç

è

ö

t

(

+ t_REP

)

RISE

LEDn_{ON_ TIME _COUNT}

³

´ f_CLK+ 4

÷

ø

PCKDIV

(2)

t_{ON(min) .}

Switch

Closed

6-V OVP

t

1

t

2

t

3

t_{RISE(LEDx) .}

t_{REP .}

//

1 PWM period

maximum

t₁LEDxON = TCNT

t₂Open detected

t₃FAULT register updated

Figure 19. LED Open Fault Detect Timing

7.3.8.1.1 LED Open Fault Detect Timing Example

In an LED open event, 12 LEDs are being turned on sequentially, creating the staircase waveform as shown in

Figure 20. At approximately time = 280 µs, LED6 is commanded to turn on but it is open. The TPS92661 device

fault circuit immediately clamps the node by turning the channel switch ON. As the LEDs in the string are turned

off, the previously open LED remains shorted for that cycle as the system has detected the fault and forced the

switch to stay on. Other channels continue to operate normally.

.

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Feature Description (continued)

Figure 20. LED Open Detection and Protection

7.3.9 Glitch-Free Operation

To help eliminate glitches in the LED current during register updates, the TPS92661 device implements the

atomic multi-byte writes function and the synchronous updates function.

7.3.9.1 Atomic Multi-Byte Writes

Because the LEDxON and LEDxOFF registers are 10-bits wide and span across multiple bytes, there is a

chance that during the time between the serial transmission of the lower eight bits and the upper two bits the

resulting register value is wrong. To overcome this problem, the communications protocol provides for atomic

multi-byte writes. This function updates all of the desired registers at one time, only after receiving an entire

transaction frame. For example, only after the entire nine-byte transaction frame has been successfully received,

does the device issue a write command to registers 00H-04H (which represent the LED1ON, LED2ON, LED3ON

and LED4ON registers) and transfers it to the final registers. This transfer has the additional benefit of updating

the final registers only if the cyclical redundancy check (CRC) for the transaction frame is correct.

7.3.9.2 Synchronous Updates

Serial communications are asynchronous to the TCNT period. The device can write LEDxON and LEDxOFF with

any value from 0x000 to 0x3FF at any time within the TCNT period. Consider a situation where there are no

timing restrictions on updating the final registers. When the device receives a new LEDxOFF value while the

corresponding LED is on and TCNT is already greater than the new LEDxOFF value, the LED remains on until it

reaches the LEDxOFF value in the next TCNT period. This can appear as a glitch in LED light output.

To overcome this issue, the device writes a new value LEDxOFF and stores it in a temporary register. The

device updates the final register only after TCNT reaches the next LEDxON register value. The converse is true

for write commands to a particular LEDxON. In that case, the device updates the final register only after TCNT

reaches the next LEDxOFF value. This sequence allows the device to update the LEDxOFF registers at the

corresponding LED turn-on time and update the LEDxON registers at the corresponding LED turn-off time.

When LEDxON and LEDxOFF are both set to the same value, the device interprets the setting as an LED off

condition. This is equivalent to clearing the ENON bit for that particular LED. The next time TCNT reaches the

common LEDxON and LEDxOFF value, the device ignores LEDxON and the LED turns off (if it was on) and

remains off until the device writes LEDxON and/or LEDxOFF and updates them with different value(s). More

specifically, the LEDOFF comparison takes precedence over the LEDON comparison. Figure 21 illustrates an

update example. Case (1) shows the resulting single PWM cycle on time that would occur if the writing of the

registers were not handled through a temporary register. Case (2) shows the functionality of the TPS92661,

where the register update is controlled, eliminating a false conduction cycle.

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Feature Description (continued)

LEDxOFF changed

LEDxOFF (old)

LEDxOFF (new)

LEDxON

TCNT

t

(1) LED current with glitch

due to LEDxOFF change

(2) Glitch-free LED current

t

LEDxOFF change takes effect at first

LEDxON after the change occurred

Figure 21. Glitch-Free LED Dimming Operation

7.3.9.2.1 LEDxON = LEDxOFF Boundary Condition

The synchronous update method removes a large majority of glitches that could be caused in the light output, but

one case should be considered. The reason is based on the synchronous update technique and can occur when

reducing the PWM duty cycle to zero. If the duty cycle is controlled by the LEDxOFF time, the LEDxON count is

fixed each cycle. To dim, the LEDxOFF count will be gradually reduced. Because of the way the LEDx ON/OFF

updates occur, a glitch can occur at the point when LEDxON = LEDxOFF causing the LED to remain on for a

single cycle. The recommended method to turn a channel fully off is to avoid the implementation of LEDxON =

LEDxOFF and use the corresponding ENON bit in the Enable Register for that channel. For example, to dim a

given channel to zero duty cycle: LEDxOFF reduces to LEDxON+1, then sets that channel's ENON bit to 0.

7.3.10 Internal Oscillator and Watchdog Timers

The TPS92661 device includes two watchdog timers: a Clock Watchdog Timer and a Communications Watchdog

Timer. The clock watchdog timer operates using a free-running internal oscillator. The communications watchdog

timer operates using the incoming CLK signal. Both watchdog timers only operate when enabled after power-up

by writing their respective enable bits to a 1 in the SYSCFG register (CKWEN for the clock watchdog timer and

CMWEN for the communications watchdog timer). The Default LED State Register (DEFLED) determines which

state the LEDs are placed in during a watchdog timeout period. (see the Default LED State Register (DEFLED) )

section for details.

The Figure 22 shows the subsequent state flow after a watchdog timer limit is reached.

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Feature Description (continued)

POR Completes

NO

Normal

Comms WD

Overflow

Is CMWEN = 1?

YES

operation

NO

Clock WD Overflow

Clock Returns

Apply On/Off to

LEDs per

Comms WD

Overflow?

Is CKWEN = 1?

YES

Clock Returns

DEFLED

register setting

NO

UART Reception

No: Comms

Not Processed

Hold DC State

Is Clock

Present?

Figure 22. Watchdog Timer Overflow Flow Chart

7.3.10.1 Clock Watchdog Timer

If the external CLK input stops toggling for 32 internal oscillator cycles ( approximately 14 µs, typical) the clock

watchdog timer times out and all of the LEDs are turned on or off according to the programmed values in the

DEFLED register. They remain in that state until CLK begins toggling again. During this time, the device does not

receive or transmit UART communications. The device does not reset the internal registers in the event of clock

loss, and the LEDs begin turning on and off according to their LEDxON/LEDxOFF register settings only when the

clock returns. If the clock watchdog timer is not enabled the TPS92661 is capable of operating at frequencies

down to 0 Hz.

~2.3MHz

Count 2⁵WD Ticks

Go to state

Internal WD

Oscillator

defined by

DEFLED

Registers

0xC2-0xC3

Q5

5-Bit Counter

TPS92661 CLOCK Pin

CLR

Clear on rise or fall

Register 0xC1

Bit D3

CKWEN

Figure 23. Clock Watchdog Timer Logic

7.3.10.2 Communications Watchdog Timer

Similarly, if the CLK remains running but the device receives no transaction with a correct CRC for a period of

2²²CLK cycles, the communications watchdog timer times out and the device sets the LEDs to the state defined

in the DEFLED register. Only after a valid UART command has been received with a correct CRC do normal

PWM duty cycles resume on the LED outputs.

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Feature Description (continued)

Count 2²²CLOCK Ticks

Q22

Go to state

defined by

DEFLED

Registers

0xC2-0xC3

TPS92661 CLOCK Pin

22-Bit Counter

CLR

Correct UART Packet

Received (CRC pass)

Register 0xC1

Bit D2

CMWEN

Figure 24. Communications Watchdog Timer Logic

7.4 Device Functional Modes

The TPS92661 device may be configured and controlled using a MCU connected via a standard serial UART. Up

to eight devices may be connected to the same UART to form a network.

7.4.1 Digital Interface Connections

7.4.1.1 Address (ADR0, ADR1, and ADR2 Pins)

The address pins should be tied to VIN or GND to set the address of the TPS92661. Up to eight TPS92661s

can exist on the same network. See Table 2 for a summary of device address configurations.

7.4.1.2 Clock (CLK Pin)

The CLK pin is the input for the primary system clock. It serves as the time basis for both the UART, as well as

the LED PWM hardware. The device functions with a clock input as high as 16 MHz. The clock rate should be

selected based on the desired UART bit rate. CLOCK can be provided by the PWM peripheral of the master

microcontroller, or by a local oscillator. All TPS92661s on the same network should share the same clock.

7.4.1.3 Internal Charge Pump (CPP Pin)

The CPP pin functions as the output of the internal charge pump. The device uses the charge pump voltage as

the gate drive voltage for the internal floating switches. Bypass the CPP pin to the LED12 pin with a capacitor

with a value of at least 0.1 µF.

7.4.1.4 Enable (EN Pin)

The ENABLE pin is an active-high enable signal for the TPS92661 device. When driven low, it resets all internal

switches, state machines, and registers to their default states. The reset state of the switches is closed, and

registers are reset (see Table 7). The managing microcontroller can actively drive this pin. Alternatively tie this

pin to VCC or VIN to enable the device at power-up. The EN pin input has internal protections against charge

injection and requires no series resistor when tied to one of the local power rails.

7.4.1.5 GND Pin

Proper operation of the TPS92661 device requires that all GND pins MUST be tied to system ground.

7.4.1.6 Receive (RX Pin)

The RX pin is the TPS92661 UART input. It should be connected to the UART Tx pin of the MCU, as well as the

other TPS92661 RX pins on the network. The bit rate of data transmitted on this pin should be at CLOCK / 16,

and is fixed at that bit rate.

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Device Functional Modes (continued)

7.4.1.7 Synchronization (SYNC Pin)

The SYNC pin synchronizes the internal PWM counter of the TPS92661 device. At reset, the SYNC pin acts as

an input, and a low-to-high pulse on this pin resets the TCNT register to 0x000. When an external microcontroller

drives this pin, the pulse should be generated at the LED PWM frequency. To calculate this frequency, use

Equation 3.

f_PWM= CLOCK / Programmed Divisor / 1024

(3)

Writing a ‘1’ to the SCMAST bit in the SYSCFG register programs the SYNC pin to function as an output.

Establish only one TPS92261 device as the master if the application requires this output configuration. To

prevent contention on the SYNC line configure only one SYNC master (driver) in the system at a time. The

SYNC pin is internally pulled down and can remain unconnected if it is not used.

7.4.1.8 Transmit (TX Pin)

The TX pin is the UART output of the TPS92661 device. Connected the TX pin to the microcontroller UART RX

pin. The bit rate of data transmitted on this pin is f_CLK/16, and is fixed at that bit rate. Connect all TX pins on each

TPS92661 device that are on the same network. Connect a single, 100-kΩ pull-up resistor from TX to VCC.

Because the TX pin is a tri-state output, an external pull-up resistor is required to avoid triggering false start

conditions at the microcontroller UART.

7.4.1.9 Primary Power Supply (VIN Pin)

The VIN pin is the primary power supply input for the TPS92661 device. Connect the VIN pin to a nominally 5-V

supply, and include a bypass capacitor nearby with a value of at least 0.1-µF.

7.4.1.10 On-Board 3.3-V Supply (VCC Pin)

The VCC pin is the input for the positive rail of the internal digital I/Os. See the Internal Regulator section for

configuration guidelines.

7.4.2 Internal Pin-to-Pin Resistance

There are pin pairs for each digital I/O on the TPS92661 device. This allows for easy routing between multiple

devices on a single sided PCB. To help estimate the voltage drop across the pin-to-pin connection, see

Figure 26.

25

VIN

Enable

Tx

Rx

Sync

Clock

V(in)

22.5

20

14

8

23

29

CLK

SYNC

RX

17.5

15

6

31

25

12.5

10

12

TX

EN

10

4

27

33

7.5

5

2.5

0

-40

-20

0

20

40

60

80

100 120 140

Ambitent Temperature (°C)

D014

Figure 25. Pin-to-Pin Internal Resistance

7.4.3 UART Physical Layer

Figure 26. Pin-to-Pin Cross-Device Resistance

The microcontroller unit UART communicates with the TPS92661 device using serial TTL signaling. The TX and

RX lines are connected to the TPS92661 device as shown in Figure 27. The pairs of TX and RX pins on the

TPS92661 device are feed-through pins, and either pin may be used to connect the TPS92661 device to the

network.

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Device Functional Modes (continued)

A tri-state buffer drives the TX output. In order to prevent false START bit detection by the microcontroller unit

when a TPS92661 device releases the bus, place an external, 100-kΩ pull-up resistor on the RX input return line

of the microcontroller unit.

TPS92661

U1

TPS92661

U2

MCU

TX

RX

UART

RX

TX

Figure 27. Communications Connections

7.4.4 UART Clock and Baudrate

The UART operates with eight data bits, one stop bit and no parity (8 – 1). Figure 28 shows the waveform for an

individual byte transfer on the TTL UART.

VCC

Logic 1

START

³0´

STOP

³1´

Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

Bit 6

Bit 7

GND

Logic 0

Figure 28. UART 8 – 1 Signaling

A logic “1” state occurs when the device drives the line to the VCC voltage. A logic “0” state occurs when the

device drives the line to system ground. The line remains in the high/logic “1” state when idle. Figure 29 and

Figure 30 illustrate sending actual data bytes and are intended to represent what an actual UART waveform

displays on an oscilloscope or logic analyzer.

5h

Ch

VCC

GND

Logic 1

Logic 0

START

³0´

Bit 0

³1´

Bit 1

³0´

Bit 2

³1´

Bit 3

³0´

Bit 4

³0´

Bit 5

³0´

Bit 6

³1´

Bit 7

³1´

STOP

³1´

Figure 29. UART Sending 0x26 Byte (0010 0110)

6h

2h

VCC

GND

Logic 1

Logic 0

START

³0´

Bit 0

³0´

Bit 1

³1´

Bit 2

³1´

Bit 3

³0´

Bit 4

³0´

Bit 5

³1´

Bit 6

³0´

Bit 7

³0´

STOP

³1´

Figure 30. UART Sending 0x26

The baud rate is based on the CLOCK input and is one-sixteenth of the CLOCK input frequency (see Table 1 for

some examples). The UART uses 16× oversampling on the incoming asynchronous RX signal.

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Table 1. UART Baud Rate Examples

CLK FREQUENCY (MHz)

6.4

BAUD RATE (kbps)

400

8.0

500

800

12.8

16.0

1000

Set the master microcontroller unit to support the same baud rate as is defined by the input CLOCK frequency.

7.4.5 UART Communications Reset

The microcontroller unit can reset the device UART and protocol state machine at any time by holding the RX

input low for a period of at least 12 bit times (16 × 12 CLK periods). This period signifies a break in

communications and causes the TPS92661 devices on the network to reset to a known-good state for receiving

the next command frame. The device immediately aborts any response frames in progress.

NOTE

A communications reset does not reset the registers and does not halt normal LED PWM

operation.

7.4.6 UART Device Addressing

Connecting terminals ADR2, ADR1, and ADR0 to GND or VCC sets the device address for each TPS92661

device. This allows up to eight different devices (addressable (0h to 7h)) for a total of 8 × 12 = 96 LEDs per

array. See Table 2 for device address configuration.

Table 2. Device Address Configurations

ADR2

ADR1

ADR0

DEVICE ADDRESS

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

2

3

4

5

6

7

7.4.7 UART Communications Protocol

The UART communication process uses a command/response protocol mastered by the MCU to write and read

the registers on each TPS92661 device. This means that the TPS92661 device never initiates traffic onto the

network. The protocol maps the registers into an address space on each device. All of the registers are read-

write (R/W). See the Registers section for a register list.

The MCU uses the protocol to initiate a communication transaction by sending a command frame. This command

frame addresses either one TPS92661 device directly or broadcasts to all TPS92661 devices on the network.

This addressing may cause a response frame to be sent back from the slave TPS92661 device depending on

the command type of the command frame. There are three types of command frames:

•

Single Device Write from MCU to a specific TPS92661 device (1, 2, 5, 10 or 15 bytes of data)

Single Device Read from MCU to a specific TPS92661 device (1, 2, 5, 10 or 15 bytes of data)

Broadcast Write from the MCU to all TPS92661 devices (0, 1, 2, 5, 10 or 15 bytes of data)

There is only one response frame type. An addressed slave following a ‘Single Device Read’ command from the

master MCU sends his frame type.

All command and response frames are multi-byte and the total number of transmitted bytes depends on the

specific command type being communicated.

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7.4.7.1 Example 1:

Command frame with CMD_TYPE = “2” (Single Device Write of 5 Bytes):

DESCRIPTION

NUMBER OF BYTES

Command Frame Init

1

5

2

9

Starting Register Address

Data

CRC

Total

7.4.7.2 Example 2:

Response frame with RESP_BYTES = ”2”:

DESCRIPTION

NUMBER OF BYTES

Response Frame Init

1

2

5

Data

CRC

Total

7.4.7.3 Example 3:

Broadcast Write Synchronization Command frame (Init = B8h):

DESCRIPTION

Command Frame Init

CRC

NUMBER OF BYTES

1

2

3

Total

The Transaction Frame Description section describes the construction of these frames and the various byte

types transmitted.

7.4.8 Transaction Frame Description

There are four byte-types used within a transaction frame. These include the following:

•

Frame Initialization (1 byte)

Register Address (1 byte)

N Data Bytes (N = 0, 1, 2, 5, 10 or 15)

Cyclic Redundancy Code (CRC) error checking (2 bytes)

Write & Read Command Frame Structure:

Cmd Frame Init

Register Address

N Bytes of Data

CRC checksum

Response Frame Structure:

Rsp Frame Init

N Bytes of Data

CRC checksum

Synchronization Command Frame Structure:

Cmd Frame Init CRC checksum

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7.4.9 Frame Initialization Byte

The frame initialization byte identifies the frame as being either a command frame or response frame. The

command frame byte includes fields specifying the request type (which details the number of bytes to be sent)

and the slave device ID. The response frame includes the number of bytes to be received by the microcontroller.

7

6

5

4

3

2

1

0

Command Frame Init

Response Frame Init

FRM_TYPE = 1

FRM_TYPE = 0

CMD_TYPE

RESERVED

DEVID_DATACNT

RESP_BYTES

The fields shown in the frame initialization byte above are described in the table below.

Value

(Binary)

# of Bytes

in Frame

Description

0

1

Response Frame

Command Frame

FRM_TYPE

Bit 7

0000

0001

0010

0011

0100

0101

0110

0111

1000

1001

1010

1011

1100

1101

1110

1111

5

6

Single Device Write (1 byte of data)

Single Device Write (2 bytes of data)

Single Device Write (5 bytes of data)

Single Device Write (10 bytes of data)

Single Device Write (15 bytes of data)

Reserved

9

14

19

Reserved

4+n

4

Broadcast Write (see DEVID_DATACNT for number of bytes of data)

Single Device Read (1 byte of data)

Single Device Read (2 bytes of data)

Single Device Read (5 bytes of data)

Single Device Read (10 bytes of data)

Single Device Read (15 bytes of data)

Reserved

CMD_TYPE

Bits 6:3

4

Reserved

For Single Device Write or Read:

bbb

3-bit device ID (defined by the terminals ADR2…ADR0)

For Broadcast Write:

000

001

Synchronization Command (no data)

1 byte of data

DEVID_DATACNT

Bits 2:0

010

2 bytes of data

011

5 bytes of data

100

10 bytes of data

101

15 bytes of data

110-111

Reserved. These values are reserved for future use and must not be written.

000

001

1 data byte to follow (plus two bytes for CRC)

2 data bytes to follow (plus two bytes for CRC)

5 data bytes to follow (plus two bytes for CRC)

10 data bytes to follow (plus two bytes for CRC)

15 data bytes to follow (plus two bytes for CRC)

Reserved

010

RESP_BYTES

Bits 2:0

011

100

101-111

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7.4.10 Register Address

The protocol allows 1, 2, 5, 10 or 15 successive register locations from the addressed register to be written by a

single command frame. The register address byte identifies the first TPS92661 device register being written or

read, as described in the Register Map section.

7.4.11 Data Bytes

The frame initialization byte specifies the number of data bytes to be included in the frame.

7.4.12 CRC Bytes

CRC-16-IBM calculates the CRC bytes. The CRC bytes allow detection of errors within the transaction frame.

The device increments the CRC Error Count Register (CERRCNT) each time a CRC error occurs (see Register

Map for details).

7.4.13 Registers

The registers in the TPS92661 device contain programmed information and operating status. During the power-

up period, the TPS92661 device resets the registers to the default values as listed below. Register addresses

marked RESERVED or not shown in the register map may be written with any value but always returns a 0.

7.4.13.1 LED ON Registers

The device stores the LED ON registers (LEDxON) for each individual LED with 10-bit resolution and organizes

them as groups of five bytes for every four LEDs. This organization creates a total of 15 LED ON registers for the

string of 12 LEDs. The address range used for these registers is 00h to 0Eh. Refer to Table 7 for complete list of

LED ON registers.

ADDR

00h

REGISTER

LED1ONL

LED2ONL

LED3ONL

LED4ONL

LED1_4ONH

D7

D6

D5

D4

D3

D2

D1

D0

DEFAULT

00000000

LED1ON[7:0]

LED2ON[7:0]

LED3ON[7:0]

LED4ON[7:0]

01h

02h

03h

04h

LED4ON[9:8]

LED3ON[9:8]

LED2ON[9:8]

LED1ON[9:8]

LEDxON[9:0] defines the count value within the 10-bit TCNT period when bypass switch x should be

opened to turn LEDx on (x = 1 to 12).

7.4.13.2 LED OFF Registers

The device stores the LED OFF registers (LEDxOFF) for each individual LED with 10-bit resolution and

organizes them as groups of five bytes for every four LEDs. This organization creates a total of 15 LED OFF

registers for the string of 12 LEDs. The address range used for these registers is 20h to 2Eh. Refer to Table 7 for

complete list of LED OFF registers.

ADDR

20h

REGISTER

LED1OFFL

LED2OFFL

LED3OFFL

LED4OFFL

LED1_4OFFH

D7

D6

D5

D4

D3

D2

D1

D0

DEFAULT

00000000

LED1OFF[7:0]

LED2OFF[7:0]

LED3OFF[7:0]

LED4OFF[7:0]

21h

22h

23h

24h

LED4OFF[9:8]

LED3OFF[9:8]

LED2OFF[9:8]

LED1OFF[9:8]

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LEDxOFF[9:0] defines the count value within the 10-bit TCNT period when bypass switch x should be

closed to turn LEDx off (x = 1 to 12).

7.4.13.3 Alternate LED On/Off Registers

In the low address space starting at 00h that is defined above, all of the LEDxOFF registers follow all of the

LEDxON registers. The higher address space starting at 40h maps the LEDxON and LEDxOFF pairs together so

that the device requires a write of only 10 data bytes to update both the on and the off times for a given set of

four LEDs. The registers that exist at addresses {40h-5Dh} are an alias for the registers that exist at addresses

{0h-0Eh, 20h-2Eh}. In other words, a write to the register at address 00h affects the register contents at address

40h, and vice versa.

7.4.13.4 Enable Registers

The ENABLE registers (ENON and ENOFF) determine whether a particular LEDxON or LEDxOFF value is

enabled. In other words, an LED turns on only when TCNT reaches LEDxON if the corresponding ENON bit is

set. Conversely, an LED turns off only when TCNT reaches LEDxOFF if the corresponding ENOFF bit is set. In

this way, LEDs may be turned on fully, turned off fully, or modulated at a given duty cycle by programming the

appropriate ENON and ENOFF register bits.

ADDR

B0h

REGISTER

ENONL

D7

D6

D5

D4

D3

D2

ENON[12:9]

ENOFF[12:9]

D1

D0

DEFAULT

00000000

ENON[8:1]

B1h

ENONH

RESERVED

B2h

ENOFFL

ENOFFH

ENOFF[8:1]

B3h

ENON[12:1] determine whether the device uses the corresponding LEDxON to turn on the LED.

0 = Do nothing when TCNT = LEDxON

1 = Turn LED on when TCNT = LEDxON

ENOFF[12:1] determine whether the device uses the corresponding LEDxOFF to turn off the LED.

0 = Do nothing when TCNT = LEDxOFF

1 = Turn LED off when TCNT = LEDxOFF

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7.4.13.5 Control Registers

The control registers allow control and monitoring of several functions. The control registers occupy addresses

C0h through C5h.

7.4.13.5.1 PWM Clock Divider Register (PCKDIV)

ADDR

C0h

REGISTER

PCKDIV

D7

D6

D5

D4

D3

D2

D1

D0

DEFAULT

RSVD

DDEC[1:0]

RSVD

DPWR2[2:0]

00000011

DPWR2[2:0]: This 3-bit value sets the power-of-2 divider for the incoming CLK signal before sending it to

the decimal divider. Power-of-2 divider mapping:

DPWR2[2:0]

Divide by:

0

1

2

3

4

5

6

7

2

4

8

16

32

64

reserved⁽¹⁾

The default value of DPWR2 is 3. This sets the initial power-of-2 divider to divide-by-16 at reset.

DDEC[1:0]: This 2-bit value sets the decimal divider for the internal signal coming from the power-of-2

divider. Decimal divider mapping:

DDEC1:0]

Divide by:

0

1

2

3

1

3

5

reserved⁽¹⁾

The default value of DDEC is 0. This sets the initial decimal divider to divide-by-1 at reset. Using the two serially

connected dividers in combination, clock dividers of various values are possible.

(1) If any of the reserved values are written to DPWR2[2:0] or DDEC[1:0], the PWM clock divider is set to

divide-by-16, regardless of any other settings.

PWM Clock Divider

Examples:

DPWR2[2:0] = 0

DDEC[1:0] = 0

→ PWM Clock = CLK / 2

DPWR2[2:0] = 1

DDEC[1:0] = 2

→ PWM Clock = CLK / 20

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7.4.13.5.2 System Configuration Register (SYSCFG)

ADDR

C1h

REGISTER

SYSCFG

D7

D6

D5

D4

D3

D2

D1

D0

DEFAULT

RESERVED

CKWEN CMWEN SCMAST

PWR

00000000

PWR: This bit is reset to 0 upon power-up or EN low. It may be written to a 1 by the micro-controller

(MCU). Reading this bit allows the MCU to detect when there has been a power cycle.

0 = A power cycle or EN low has occurred since last write to a ‘1’

1 = No power cycle or EN low has occurred since the last write to a ‘1’

SCMAST: The Synchronization Master bit determines whether the TPS92661 device is a synchronization

master or not. There should be only ONE Sync Master in the system.

0 = Slave. A high input value on SYNC resets TCNT to 0.

1 = Master. The TPS92661 device generates a high pulse one CLK cycle

long on SYNC when TCNT = 1023 and the PWM clock divider is about to

roll over. SYNC may be connected to the next TPS92661 device in order

to synchronize multiple TPS92661 devices with respect to each other.

CMWEN: Communications Watchdog Timer Enable.

0 = Communications watchdog timer disabled

1 = Communications watchdog timer enabled

CKWEN: Clock Watchdog Timer Enable

0 = Clock watchdog timer disabled

1 = Clock watchdog timer enabled

7.4.13.6 Default LED State Register (DEFLED)

ADDR

C2h

REGISTER

DEFLEDL

DEFLEDH

D7

D6

D5

D4

D3

D2

D1

D0

DEFAULT

00000000

DEFLED[8:1]

C3h

RESERVED

DEFLED[12:9]

DEFLED[12:1]: Default LED State register. This register determines which state to place the LED in

when one of the watchdog timers times out.

0 = LED off

1 = LED on

7.4.13.7 PWM Period Counter Register (TCNT)

ADDR

C4h

REGISTER

TCNTL

D7

D6

D5

D4

D3

D2

D1

D0

DEFAULT

00000000

TCNT[7:0]

C5h

TCNTH

RESERVED

TCNT[9:8]

TCNT[9:0]: This is the PWM period count value. The TCNT register automatically counts from 0 to 1023

and wraps. It is provided here with read/write access for diagnostic purposes. Writes to the TCNT register

are loaded upon the next rising edge of CLK when there is a SYNC pulse present.

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7.4.13.8 Diagnostic Registers

The diagnostic registers hold the results of various faults and status flags for the system. The diagnostic registers

exist in the address range E0h to E2h.

ADDR

E0h

REGISTER

FAULTL

D7

D6

D5

D4

D3

D2

D1

D0

DEFAULT

00000000

FAULT[8:1]

E1h

FAULTH

RESERVED

FAULT[12:9]

E2h

CERRCNT

CERRCNT[7:0]

FAULT[12:1]: Fault Register

0 = an LED fault has not occurred

1 = an LED fault has occurred

The LED open and short fault detection circuitry is sampled just before the corresponding bypass switch

is closed. If a fault exists at this time instant, a 1 is latched into the associated FAULT register bit. The

FAULT register bits must be cleared manually by writing them back to 0. If an LED fault condition still

exists at the next PWM period, the device immediately resets the corresponding FAULT register bit to a

1. Writing the FAULT register bits to 1 has no effect.

CERRCNT[7:0]: CRC Error Count Register

This register value is incremented each time a CRC error is received. This register may be read by the

MCU and then written back to 0 to clear the count. The CERRCNT value saturates at FFh; it does not

wrap back to 0 when it reaches FFh. The CERRCNT register is not automatically cleared when a

communications reset is received. It must be cleared manually by writing it back to 0. Note that the

CERRCNT register can be written to any 8-bit value. This is intended for diagnostic purposes.

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7.5 Programming

7.5.1 Read / Write Register Flow Chart

7.5.1.1 Register Write Flow Chart

Build Write Transaction

Frame

Build Frame Initialization

Byte

Bit 7 = 1

Bit 6:3 = 4'b0000

Bit 2:0 = TPS92661 Address

1^st

Byte

2^nd

Byte

TPS92661 register address

to write

Append Least Significant

Byte (LSB) of CRC-16 to

Write Transaction Buffer

4^th

Byte

3^rd

Byte

Data byte

Append Most Significant

Byte (MSB) of CRC-16 to

Write Transaction Buffer

5^th

Byte

Calculate CRC-16 of

Bytes 1-3

Send 5 bytes via UART to

TPS92661

Figure 31. Register Write Example

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Programming (continued)

7.5.1.2 Register Read Flow Chart

Build Read Transaction

Frame (4 Bytes)

Reverse the bit order of

the CRC-16 bytes

[0:7]

Bit 7 <-> Bit 0

Bit 6 <-> Bit 1

Bit 5 <-> Bit 2

Bit 4 <-> Bit 3

-----

Build Frame Initialization

Command Byte

1^st

Send 4 bytes via UART to

TPS92661

Bit 7 = 1

Byte

Bit 6:3 = 4'b1000

Bit 2:0 = TPS92661 Address

[8:15]

Bit 15 <-> Bit 8

Bit 14 <-> Bit 9

Bit 13 <-> Bit 10

Bit 12 <-> Bit 11

2^nd

Byte

TPS92661 register address

to read

Receive 4 bytes via

UART from TPS92661

1^stByte: Frame

Initialization Response

Byte

Bit 7 = 0

Bit 6:3 = 4'b0000

Bit 2:0 = 3'b000

CRC-16 match?

-----

Calculate CRC-16 of

Bytes 1-2

Compare calculated and reversed

LSB with received LSB

-----

Compare calculated and reversed

MSB with received MSB

2^ndByte: Read Data

YES

2^ndByte = Read Data

3^rdByte: CRC-16 LSB

(Bit Reversed [7:0])

Append Least Significant

Byte (LSB) of CRC-16 to

Write Transaction Buffer

3^rd

Byte

4^thByte: CRC-16 MSB

(Bit Reversed [15:8])

NO

Append Most Significant

Byte (MSB) of CRC-16 to

Write Transaction Buffer

Data is invalid.

Discard read byte.

Accumulate error?

4^th

Byte

Calculate CRC-16 of

received Bytes 1-2

Figure 32. Register Read Example

7.5.2 Complete Transaction Example

The pseudo-code below shows a pair of transactions: a write of the LEDOFF times for LEDs 1-4 followed by a

read of the same registers (LED1OFF = 200, LED2OFF = 410, LED3OFF = 620, LED4OFF = 830).

Table 3. Write Command (MCU-to-TPS92661 Device)

tx_init (0x90)

tx_addr (0x20)

tx_data (0xc8)

tx_data (0x9a)

tx_data (0x6c)

tx_data (0x3e)

tx_data (0xe4)

Single device write of 5 bytes (Device ID = 0)

Register address = 0x20 (LED1OFFL)

LED1OFFL = Low_Byte (200)

LED2OFFL = Low_Byte (410)

LED3OFFL = Low_Byte (620)

LED4OFFL = Low_Byte (830)

LED1_4OFFH = High_Byte (830) << 6

High_Byte (620) << 4

High_Byte (410) << 2

High_Byte (200)

tx_crc1 (0x88)

tx_crc2 (0x57)

CRC1 = Low_Byte (CRC-16-IBM)

CRC2 = High_Byte (CRC-16-IBM)

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Table 4. Read Command (MCU-to-TPS92661 Device)

tx_init (0xd0)

Single device read of 5 bytes (Device ID = 0)

Register address = 0x20 (LED1OFFL)

CRC1 = Low_Byte (CRC-16-IBM)

tx_addr (0x20)

tx_crc1 (0x5c)

tx_crc2 (0x18)

CRC2 = High_Byte (CRC-16-IBM)

Table 5. Read Response (MCU-to-TPS92661 Device)

rx_init (0x02)

Read Response, 5 data bytes to follow

rx_data (0xc8)

rx_data (0x9a)

rx_data (0x6c)

rx_data (0x3e)

rx_data (0xe4)

LED1OFFL = Low_Byte (200)

LED2OFFL = Low_Byte (410)

LED3OFFL = Low_Byte (620)

LED4OFFL = Low_Byte (830)

LED1_4OFFH = High_Byte (830) << 6

High_Byte (620) << 4

High_Byte (410) << 2

High_Byte (200)

rx_crc1 (0x78)

rx_crc2 (0x3b)

CRC1 = Low_Byte (CRC-16-IBM)

CRC2 = High_Byte (CRC-16-IBM)

Must be reversed when read. See CRC Calculation

Programming Examples section.

As an additional example, the following pseudo-code shows a 2-byte write to TPS92661 Address 5, Register

0xB0 (ENON) with data of 0x55 to register 0xB0 and 0x05 to register 0xB1. Data sent (hex): 8D B0 55 05 D5 D8

Table 6. Write Command (MCU-to-TPS92661 Device)

tx_init (0x8D)

tx_addr (0xB0)

tx_data (0x55)

tx_data (0x05)

tx_crc1 (0xD5)

tx_crc2 (0xD8)

Single device write of 2 bytes (Device ID = 5)

Register address = 0xB0 (ENON)

ENONL = 0101 0101b

ENONH = 0000 0101b

CRC1 = Low Byte(CRC-16-IBM)

CRC2 = High Byte(CRC-16-IBM)

The UART waveform associated with the example in Table 6 is shown in Figure 33.

Dh

8h

0h

Bh

5h

0h

5h

Dh

8h

Dh

S

p

S

p

S

p

S

p

S

p

S

p

St 1 0 1 1 0 0 0 1 St 0 0 0 0 1 1 0 1 St 1 0 1 0 1 0 1 0 St 1 0 1 0 0 0 0 0 St 1 0 1 0 1 0 1 1 St 0 0 0 1 1 0 1 1

Cmd: 0x8D

Data: 0xB0

(ENONL)

0xB0=0x55

0xB1=0x05

CRC LSB

0xD5

CRC MSB

0xD8

(1 000_1 101)

(1^stReg Data)

(2^ndReg Data)

Figure 33. 2-Byte Write Example Waveform

After this write had completed, the device enables all of the odd numbered LEDs (LED1, LED3, …, LED11) to

turn on when TCNT = LEDxON register, while all of the even numbered LEDs remain off.

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7.5.3 CRC Calculation Programming Examples

The C function below shows an example of how to generate the CRC bytes correctly for a transmission to the

TPS92661 devices:

Uint16 crc_16_ibm(Uint8 *buf, Uint8 len)

{

Uint16 crc = 0;

Uint16 I;

while (len--){

crc ^= *buf++;

for (I = 0; I < 8; I++){

crc = (crc >> 1) ^ ((crc & 1) ? 0xa001 : 0);

}

return crc;

}

The CRC is transmitted LSByte first to/from the TPS92661 device.

Upon reading data from the TPS92661 device, the MCU should calculate and compare the CRC to determine

whether valid data was received.

NOTE

The calculated CRC bytes must be bit-reversed before comparison to the received CRC

bytes

bool is_crc_valid(Uint8 *rx_buf, Uint8 crc_start)

{

Uint16 crc_calc;

// Calculated CRC

Uint8 crc_msb, crc_lsb; // Individual bytes of calculated CRC

// Calculate the CRC based on bytes received

crc_calc = crc_16_ibm(rx_buf, crc_start);

crc_lsb = (crc_calc & 0x00FF);

crc_msb = ((crc_calc >> 8) & 0x00FF);

// Perform the bit reversal within each byte

crc_msb = reverse_byte(crc_msb);

crc_lsb = reverse_byte(crc_lsb);

// Do they match?

if((*(rx_buf + crc_start) == crc_lsb) && (*(rx_buf + crc_start + 1) == crc_msb)){

return TRUE;

}

else{

return FALSE;

}

One way to perform the bit reversal is shown in the following C code:

Uint8 reverse_byte(Uint8 byte)

{

// First, swap the nibbles

byte = (((byte & 0xF0) >> 4)| | ((byte & 0x0F) << 4));

// Then, swap bit pairs

byte = (((byte & 0xCC) >> 2) | ((byte & 0x33) << 2));

// Finally, swap adjacent bits

byte = (((byte & 0xAA) >> 1) | ((byte & 0x55) << 1));

// We should now be reversed (bit 0 <--> bit 7, bit 1 <--> bit 6, etc.)

return byte;

7.5.4 Code Examples to Implement Register Reads/Writes

The C functions below show examples of how to code a single register write and single register read. It is

recommended that the user get this code running first and then expand to some of the other commands and

multi-byte reads and writes.

Write Example:

void lmm_wr_1_reg(Uint8 lmm, Uint8 regaddr, Uint8 data)

{

Uint8 TxBuf[5];

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Uint16 I;

// We must first assemble the bytes and CRC them

TxBuf[0] = (0x80 | lmm);

TxBuf[1] = regaddr;

TxBuf[2] = data;

// Get the CRC back

I = crc_16_ibm(TxBuf, 3);

// Process and store bytes

TxBuf[3] = (I & 0x00FF); // LSByte

TxBuf[4] = ((I >> 8 & 0x00FF); // MSByte

/* INSERT MCU-SPECIFIC UART CODE HERE */

// Now we can send it to the matrix network

for(I = 0; I < 5; I++){

lmm_uart_xmit(TxBuf[i]);

}

Read Example:

Uint8 lmm_rd_1_reg(Uint8 lmm, Uint8 regaddr)

{

/* DATA WILL BE AVAILABLE IN RxBuf ON RETURN */

Uint8 TxBuf[4];

Uint16 I;

// We must first assemble the request and CRC it

TxBuf[0] = (0xC0 | lmm);

TxBuf[1] = regaddr;

// Get the CRC back

I = crc_16_ibm(TxBuf, 2);

// Process and store bytes

TxBuf[2] = (I & 0x00FF); // LSByte

TxBuf[3] = ((I >> 8) & 0x00FF); // MSByte

// Also make sure we are prepared to receive the data from the LMM

ReturnBytes = 1+1+2; // This is the number of bytes we expect to get back

/* 1 Response Frame Init + 1 Data + 2 CRC */

GatheredBytes = 0;

/* INSERT MCU-SPECIFIC UART CODE HERE */

// Now we can send it to the matrix network

for(I = 0; I < 4; I++){

lmm_uart_xmit(TxBuf[i]);

}

/* INSERT MCU-SPECIFIC UART CODE HERE */

// Now we can send the request to the matrix network

// This is basically pseudo-code for however your MCU receive works

while(GatheredBytes != 4);

// Check the CRC (should be in RxBuf[2] and [3])

if(is_crc_valid(RxBuf, 2)){

return TRUE;

}

else{

return FALSE;}

}

7.6 Register Map

Table 7. Register Map

ADDR

REGISTER

D7

D6

D5

LED ON REGISTERS

LED1ON[7:0]

D4

D3

D2

D1

D0

DEFAULT

00h

01h

02h

03h

LED1ONL

LED2ONL

LED3ONL

LED4ONL

00000000

LED2ON[7:0]

LED3ON[7:0]

LED4ON[7:0]

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Register Map (continued)

Table 7. Register Map (continued)

ADDR

04h

05h

06h

07h

08h

09h

0Ah

0Bh

0Ch

0Dh

0Eh

REGISTER

LED1_4ONH

LED5ONL

D7

D6

D5

LED3ON[9:8]

LED5ON[7:0]

D4

D3

D2

D1

D0

DEFAULT

00000000

LED4ON[9:8]

LED8ON[9:8]

LED12ON[9:8]

LED2ON[9:8]

LED1ON[9:8]

LED5ON[9:8]

LED9ON[9:8]

LED6ONL

LED6ON[7:0]

LED7ON[7:0]

LED8ON[7:0]

LED7ONL

LED8ONL

LED5_8ONH

LED9ONL

LED7ON[9:8] LED6ON[9:8]

LED9ON[7:0]

LED10ONL

LED11ONL

LED12ONL

LED9_12ONH

LED10ON[7:0]

LED11ON[7:0]

LED12ON[7:0]

LED11ON[9:8]

LED OFF REGISTERS

LED1OFF[7:0]

LED10ON[9:8]

20h

21h

22h

23h

24h

25h

26h

27h

28h

29h

2Ah

2Bh

2Ch

2Dh

2Eh

LED1OFFL

LED2OFFL

LED3OFFL

LED4OFFL

LED1_4OFFH

LED5OFFL

LED6OFFL

LED7OFFL

LED8OFFL

LED5_8OFFH

LED9OFFL

LED10OFFL

LED11OFFL

LED12OFFL

LED9_12OFFH

00000000

LED2OFF[7:0]

LED3OFF[7:0]

LED4OFF[7:0]

LED4OFF[9:8]

LED8OFF[9:8]

LED12OFF[9:8]

LED3OFF[9:8]

LED2OFF[9:8]

LED1OFF[9:8]

LED5OFF[9:8]

LED9OFF[9:8]

LED5OFF[7:0]

LED6OFF[7:0]

LED7OFF[7:0]

LED8OFF[7:0]

LED7OFF[9:8]

LED6OFF[9:8]

LED9OFF[7:0]

LED10OFF[7:0]

LED11OFF[7:0]

LED12OFF[7:0]

LED11OFF[9:8]

LED10OFF[9:8]

LED ONOFF REGISTERS (Remapped LED ON and LED OFF Registers)

40h

41h

42h

43h

44h

45h

46h

47h

48h

49h

4Ah

4Bh

4Ch

4Dh

4Eh

4Fh

50h

51h

LED1ONL

LED2ONL

LED1ON[7:0]

LED2ON[7:0]

LED3ON[7:0]

LED4ON[7:0]

00000000

LED3ONL

LED4ONL

LED1_4ONH

LED1OFFL

LED2OFFL

LED3OFFL

LED4OFFL

LED1_4OFFH

LED5ONL

LED4ON[9:8]

LED4OFF[9:8]

LED8ON[9:8]

LED3ON[9:8]

LED2ON[9:8]

LED1ON[9:8]

LED1OFF[9:8]

LED5ON[9:8]

LED1OFF[7:0]

LED2OFF[7:0]

LED3OFF[7:0]

LED4OFF[7:0]

LED3OFF[9:8]

LED2OFF[9:8]

LED5ON[7:0]

LED6ON[7:0]

LED7ON[7:0]

LED8ON[7:0]

LED6ONL

LED7ONL

LED8ONL

LED5_8ONH

LED5OFFL

LED6OFFL

LED7OFFL

LED7ON[9:8]

LED6ON[9:8]

LED5OFF[7:0]

LED6OFF[7:0]

LED7OFF[7:0]

36

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

Register Map (continued)

Table 7. Register Map (continued)

ADDR

52h

53h

54h

55h

56h

57h

58h

59h

5Ah

5Bh

5Ch

5Dh

REGISTER

LED8OFFL

LED5_8OFFH

LED9ONL

D7

D6

D5

D4

D3

D2

D1

D0

DEFAULT

00000000

LED8OFF[7:0]

LED8OFF[9:8]

LED12ON[9:8]

LED12OFF[9:8]

LED7OFF[9:8]

LED6OFF[9:8]

LED5OFF[9:8]

LED9ON[9:8]

LED9OFF[9:8]

LED9ON[7:0]

LED10ONL

LED11ONL

LED12ONL

LED9_12ONH

LED9OFFL

LED10OFFL

LED11OFFL

LED12OFFL

LED9_12OFFH

LED10ON[7:0]

LED11ON[7:0]

LED12ON[7:0]

LED11ON[9:8]

LED10ON[9:8]

LED9OFF[7:0]

LED10OFF[7:0]

LED11OFF[7:0]

LED12OFF[7:0]

LED11OFF[9:8]

ENABLE REGISTERS

ENON[8:1]

LED10OFF[9:8]

B0h

B1h

B2h

B3h

ENONL

ENONH

ENOFFL

ENOFFH

00000000

RESERVED

ENON[12:9]

ENOFF[8:1]

RESERVED

ENOFF[12:9]

CONTROL REGISTERS

C0h

C1h

C2h

C3h

C4h

C5h

PCKDIV

SYSCFG

DEFLEDL

DEFLEDH

TCNTL

RSVD

DDEC[1:0]

RSVD

CKWEN CMWEN SCMAST

DEFLED[8:1]

DPWR2[2:0]

00000011

00000000

RESERVED

PWR

RESERVED

DEFLED[12:9]

TCNT[7:0]

TCNTH

RESERVED

TCNT[9:8]

DIAGNOSTIC REGISTERS

E0h

E1h

E2h

FAULTL

FAULTH

FAULT[8:1]

00000000

RESERVED

FAULT[12:9]

CERRCNT

CERRCNT[7:0]

37

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

8 Application and Implementation

8.1 Applications Information

The TPS92661 is capable of shunting any combination of 12 series LEDs at high frequency and at variable duty

cycles. This type of application requires a high bandwidth current source. The TPS92661 was developed using a

high-side sensing hysteretic buck current source and it is this type that is recommended to power the LED

channels. boost and/or buck-boost inputs may also be used, but makes the implementation more complicated

and lower performance.

8.1.1 Guidelines For Current Source

•

Operate at a switching frequency at least 250 times the TPS92661 PWM frequency. A switching frequency

between 500 times the PWM frequency and 2000 times the PWM frequency is recommended.

•

Operate current source in CCM (continuous conduction mode).

Minimize capacitance on each LED channel (capacitance between LED0 and LED12) to avoid excessive over

and undershoot when dimming.

•

Monitor the current source output current during dimming to ensure the source is staying close to its DC set-

point level.

Follow the Layout Guidelines.

8.2 Design Examples

This section offers two design examples. Each helps illustrate how the thermal limitations of a design can vary

depending on overall operating conditions and how the overall system temperature limitations directly affect the

device current rating for a given design. These temperature limitations must be considered on a case-by-case

basis.

8.2.1 12 LED, 1.2-A Application

Step 1. LED Board Requirements

Examine the requirements of the LED load board, assuming the worst case condition: LEDs on continuously.

This example assumes a worst case metal core PCB temperature of 125°C to adequately protect the LEDs.

Calculate the power required to be dissipated by the LED load board alone using Equation 4.

P_{LED_LOAD}= I_LED× V_LED× n = 1.1 A × 3.33 V × 12 = 43.956 W ≈ 44 W

where

•

n is the number of LEDs

(4)

Step 2. Estimate Device Power Dissipation

Use Figure 1 to estimate the power dissipation in the TPS92661 device. Assuming a 6-MHz clock and a 146-Hz

PWM frequency at 125°C, 4.2 mA at a 5.5-V VCC. The power dissipation calculation is shown in Equation 5.

P_{TPS92661_CONTROL}= 4.2 mA × 5.5 V ≈ 23 mW.

(5)

This value is very small compared to the net power required to be dissipated by the LED load and can be

neglected.

Step 3. Estimate Switch Power Dissipation

Calculate the worst case power dissipated in the TPS92661 switches. Using the worst case R_ALL(on)of 3400 mΩ

for Equation 6.

P_{TPS92661_SWITCHES}= (1.12 A)²× 3400 mΩ = 4.114 W

(6)

38

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

Design Examples (continued)

Step 4. Calculate the Temperature Rise

The LED load board controls temperature to a maximum of 125°C. Solder the TPS92661 device to the LED

board to create a very good thermal connection. Using the TPS92661 θ_JBmeasurement of 6.1 °C/W, can

calculate the temperature rise between the TPS92661 thermal pad and the junction temperature using

Equation 7.

T_J= T_BOARD(max)+ T_RISE= 125°C + (4.114 × 6.1) ≈ 150°C.

(7)

This is the maximum allowable junction temperature. Any time a TPS92661 internal switch is active, the net

power dissipated by the LED load board is reduced.

A properly designed LED load board inherently supports the additional power dissipation of the TPS92661

device. In this example, if all of the TPS92661 internal switches are on, the LED load board thermal loading

reduces from 44 W to 4.114 W.

8.2.2 6 LED, 1.5-A Application

The TPS92661 can be used for LED loads from 1 to 12 LEDs. When configuring for connections having fewer

than 12 LEDs, the LEDs should be connected as shown in Figure 34.

Unused Inputs Shorted

I_LED

Input

I_LED

Return

TPS92661

Figure 34. TPS92661 Connection with 6 LEDs

Step 1. Calculate the LED Load Power

As described in the 12 LED, 1.2-A Application section example, the LED load itself drives the heat sink design.

Assume the LED load board does not reach a temperature beyond what has been considered for the LEDs. In

this case assume the design ensures a maximum heat sink temperature of 90°C for the LED load power

calculated in Equation 8.

P_{LED_LOAD}= I_LED× V_LED× n = 1.5 A × 3.33 V × 6 ≈ 30 W (max)

where

•

n is the number of LEDs

(8)

Step 2. Estimate the Power Dissipation

Using Figure 3 estimate the power dissipation of the TPS92661 device. Assuming a 8.57-MHz clock and a 523-

Hz PWM frequency at 125°C read 3 mA at a 5.5-V VCC. This amount of power is so low that it can be

disregarded.

Step 3. Calculate the Worst Case Switches Power Dissipation

Calculate the maximum all switches on-resistance (R_ALL(on)(MAX)) value for each of the 6 switches that are in use.

Assume the other 6 switches are shorted externally.

P_{TPS92661_SWITCHES}= (1.5 A)²× R_ALL(on)(MAX)× (n/12) = (1.5 A)²× 3400 mΩ × (6/12) = 3.825 W

where

•

n is the number of LEDs

(9)

39

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

Design Examples (continued)

Step 4. Calculate the Temperature Rise

The LED load board controls temperature to a maximum of 90°C. Solder the TPS92661 device to the LED board

to create a very good thermal connection. Using the TPS92661 θ_JBmeasurement of 6.1 °C/W, can calculate the

temperature rise between the TPS92661 thermal pad and the junction temperature using

T_J= T_BOARD(max)+ T_RISE= 90°C + (3.825 × 6.1) ≈ 113°C

(10)

This temperature is well within the TPS92661 operating junction temperature range to provide exceptional

performance.

9 Power Supply Recommendations

9.1 General Recommendations

The TPS92661 requires a 5-V supply to power the charge pump, internal logic and references. This rail

generates a 3.3-V supply which can be used for the digital communications as outlined in the Internal Regulator

section. The TPS92661 device is not compatible with logic levels lower then 3.3 V or greater than 5 V. A

separate, high-power supply drives the LED string, as discussed in the LED Fault Detection and Protection

section.

9.2 Internal Regulator

The VCC pin is the output node of the on-board 3.3-V LDO. The VCC pin also acts as the positive voltage rail for

the device digital I/Os. If the TPS92661 device is used with a microcontroller with 3.3-V I/Os, then place an

output capacitor with a value of at least 0.1 µF at the pin for the internal LDO. Due to the internal linear regulator,

an external 3.3-V supply is not required.

If the TPS92661 device is used with 5-V microcontrollers, then the VCC pin MUST be tied to the 5-V VIN pin.

This connection overrides the internal LDO and allows the digital I/Os to signal at 5 V rather than 3.3 V.

In the rare case that the digital signaling exists at a voltage greater than 3.6 V, but less than 4.5 V, then the VCC

pin should be connected to the same voltage as the MCU I/O voltage.

Internal

Linear

Regulator

Internal

Linear

Regulator

12 RX

V_IN

5 V

V_IN

5 V

VCC

VIN

VCC

VIN

13

0.1 PF

14

13

14

0.1 PF

Figure 35. Power Connections for 3.3-V MCU

Systems

Figure 36. Power Connections for 5-V MCU

Systems

40

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

Internal Regulator (continued)

Internal

Linear

Regulator

12 RX

MCU I/O

V_IN

5 V

VCC

VIN

13

14

0.1 PF

Figure 37. Power Connections for 3.6-V to 4.5-V MCU Systems

9.3 Power Up and Reset

When V_INis greater than V_IN-UVT, all bypass switches are initially on (LEDs off) and the LEDs remain off until the

device is programmed with the corresponding LED and ENABLE registers. After the registers are programmed,

the TPS92661 device modulates the LEDs using the divided-down CLK input as the PWM clock. V_INmust be

greater than V_IN-UVTprior to sourcing current through the LED string in order to ensure a controlled start-up.

The EN input acts as an active-low reset signal for the TPS92661 device. If EN = 0, the TPS92661 device resets

to the same state as if a power cycle had occurred. All registers are reset to default values and all of the bypass

switches are turned on (LEDs off). Once the device emerges from the reset state by setting EN high, the

registers must be programmed in order for the device to begin normal operation.

9.4 VIN Power Consumption

Power consumption increases with increased clock frequency, with VIN voltage and with temperature. It is

always best to select the lowest VIN and clock frequency the system can tolerate. Guidelines for power drawn by

the device from VIN are provided in the Typical Characteristics section.

9.5 Initialization Set-Up

Figure 38 outlines the steps required to begin communication with a TPS92661 and enable the LEDs. Register

Read and Write code examples are shown in the Programming section.

41

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

Initialization Set-Up (continued)

Program 1

(&8ꢀLVꢀ³2II´. All

LED related

regulators are

disabled in HW.

TPS92661 to drive

SYNC, start MCU

Sync, or write

Yes

Synchronize?

SYNC command.

No

System is powered

up. 5V applied to

TPS92661 VIN.

Program desired

phase shift into

LEDON registers.

MCU

Configuration

Occurs.

Program default

duty cycles into

LEDOFF registers.

Program DEFLED

as desired, and set

CKWEN and/or

CMWEN bits.

Yes

TPS92661

ENABLE Used?

MCU drives

ENABLE High.

Watchdogs

desired?

No

Enable Current

Regulators.

16 Pulses on

TPS92661

CLOCK?

Send UART

Communications

Reset.

Yes

No-

Wait

Write ENON and

ENOFF bits to

begin LED PWM.

:ULWHꢀDꢀ³1´ꢀWRꢀ3:5ꢀ

bit in TPS92661.

LEDs now on,

MCU writes

LEDOFF to modify

individual LED

brightness.

Read back

SYSCFG register.

Yes-Next

Address

ERROR:

Unable to

communicate

to address.

No

SYSCFG ==

0x01?

Yes

Additional

TPS92661s in

the system?

No

Broadcast write of

PCKDIV to set

PWM frequency.

Figure 38. Power Up Sequence

42

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

10 Layout

10.1 Layout Guidelines

The final configuration of the LED matrix varies between applications and balances heat dissipation with light

output performance. Layout considerations for passive components are simple; place the VCC and VIN

decoupling capacitors close to the device and short the traces to the CPP pin capacitor. The bigger challenge is

to develop a careful layout plan that efficiently routes the current source for the LED strings.

The communication connections have been designed for ease of routing on a single-sided, metal core board.

Each connection has a parallel connection on the opposite side of the device, allowing multiple devices to use a

daisy chain configuration, easing routing requirements.

10.2 Layout Example

Figure 39 shows a TPS92661 layout example.

LED RETURN

LED INPUT

BYPASS

CAPACITOR

48 47 46 45 44 43 42 41 40 39 38 37

1

2

3

4

5

6

7

8

9

CPP

NC

36

LED0

INPUT

CONNECTOR

NC 35

GND 34

EN 33

GND

EN

GND

EN

GND

EN

TPS92661

GND

SYNC

GND

SYNC

GND

CLK

32

31

30

29

GND

SYNC

GND

SYNC

GND

DAP

GND

CLK

GND

CLK

No thermal vias if

using an aluminum

clad PCB

CLK

GND

TX

GND

GND 28

GND

TX

10 TX

27

26

TX

GND

RX

11 GND

12 RX

GND

RX

GND

RX 25

13 14 15 16 17 18 19 20 21 22 23 24

GND

BYPASS

CAPACITORS

5V

ADR0 ± ADR2 ADDRESS LINES

ARE TIED HIGH OR LOW

DEPENDING ON THE ADDRESS

Figure 39. TPS92661 Board Layout

43

TPS92661-Q1

ZHCSCS9 –SEPTEMBER 2014

www.ti.com.cn

11 器件和文档支持

11.1 商标

11.2 静电放电警告

这些装置包含有限的内置 ESD 保护。存储或装卸时，应将导线一起截短或将装置放置于导电泡棉中，以防止 MOS 门极遭受静电损

伤。

11.3 Export Control Notice

Recipient agrees to not knowingly export or re-export, directly or indirectly, any product or technical data (as

defined by the U.S., EU, and other Export Administration Regulations) including software, or any controlled

product restricted by other applicable national regulations, received from disclosing party under nondisclosure

obligations (if any), or any direct product of such technology, to any destination to which such export or re-export

is restricted or prohibited by U.S. or other applicable laws, without obtaining prior authorization from U.S.

Department of Commerce and other competent Government authorities to the extent required by those laws.

11.4 术语表

SLYZ022 — TI 术语表。

这份术语表列出并解释术语、首字母缩略词和定义。

44

TPS92661-Q1

www.ti.com.cn

ZHCSCS9 –SEPTEMBER 2014

12 机械封装和可订购信息

以下页中包括机械封装和可订购信息。这些信息是针对指定器件可提供的最新数据。这些数据会在无通知且不对

本文档进行修订的情况下发生改变。欲获得该数据表的浏览器版本，请查阅左侧的导航栏。

45

GENERIC PACKAGE VIEW

PHP 48

7 x 7, 0.5 mm pitch

TQFP - 1.2 mm max height

QUAD FLATPACK

This image is a representation of the package family, actual package may vary.

Refer to the product data sheet for package details.

4226443/A

www.ti.com

重要声明和免责声明

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型号：	TPS92661QPHPRQ1
厂家：	TEXAS INSTRUMENTS
描述：	适用于汽车前照灯系统的高亮度 LED 矩阵管理器 \| PHP \| 48 \| -40 to 125 驱动接口集成电路
文件：	总51页 (文件大小：1102K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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