TPS92511DDA [TI]

500mA 30W 阳极恒流降压型 LED 驱动器 | DDA | 8 | -40 to 125;


型号：	TPS92511DDA
厂家：	TEXAS INSTRUMENTS
描述：	500mA 30W 阳极恒流降压型 LED 驱动器 \| DDA \| 8 \| -40 to 125 驱动驱动器
文件：	总27页 (文件大小：746K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

TPS92511 500mA，65V 共阳极恒定电流降压发光二极管 (LED) 驱动器，

无外部电流感测电阻器

1 特性

3 说明

•

宽输入电压范围：4.5V 至 65V

TPS92511 是一款易于使用的 65V 恒定电流降压转换

器，用于驱动电流高达 0.5A 且效率高达 95% 的单个

LED 灯串。对于基本运行，只需 5 个外部组件，而且

由于集成了一个 N-MOSFET，无外部电流感测电阻

器，没有外部补偿，以及适当的端子分配，可实现单层

PCB。 LED 电流由一个高值外部电阻器设定，这样的

话，可实现 LED 电流的微调。另外一个高值外部电阻

器将恒定开关频率设定在 50kHz 至 500kHz 之间。电

磁干扰 (EMI) 的设计由于恒定开关频率的原因而变得

更加简单。 TPS92511 提供 4.5V 至 65V 的宽输入电

压范围。通过添加简单的外部电路，此器件甚至能够

处理具有更高输入电压的应用。

无需外部电流感测电阻器

无需外部环路补偿

易于使用，最少需要 5 个组件

1000:1 对比率可行

单层印刷电路板 (PCB) 可行

可作为高压降压稳压器运行

可作为线性电流并联稳压器运行

集成低端 N 通道金属氧化物半导体场效应晶体管

(MOSFET)

•

LED 电流可设定为高达 0.5A

典型值为 ±3.6% 的 LED 电流精度

开关频率可在 50kHz 至 500kHz 之间进行编程

电流限制保护

TPS92511 采用私有控制机制来调节 LED 电流，而无

需直接感测 LED 电流。它采用一个具有低端 N 通道

功率 MOSFET 的浮动降压拓扑结构，此拓扑结构无需

自举电容器。对于多通道系统，浮动降压拓扑结构连

同私有控制机制可在无需外部电流感测网络的前提下实

现 LED 灯串的共阳极连接。这极大地减少了接线数

量，以及整体制造成本。

VCC 欠压闭锁

热关断保护

支持模拟调光和热折返

带有外露散热焊盘的功率增强型小外形尺寸集成电

路 (SOIC)-8 封装（带散热片小外形尺寸封装

(HSOP)-8）

TPS92511 具有极快速的脉宽调制 (PWM) 调光响应时

间。例如，如果开关频率为 500kHz，最小 DIM 脉宽

为 6µs，并且调光频率为 150Hz，那么可实现大于

1000:1 的对比率。

2 应用范围

•

高功率 LED 驱动器

建筑照明

办公室嵌入式照明

汽车照明

TPS92511 采用带有外露散热焊盘的功率增强型

SOIC-8 封装。

MR-16 LED 灯

器件信息⁽¹⁾

简化应用

部件号

封装

封装尺寸（标称值）

V_IN

TPS92511

HSOP (8)

4.89mm × 3.90mm

TPS92511

(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。

VCC

VIN

LED string

I_LED

C_VCC

PGND

IADJ

GND

DIM

PWM dimming signal

R_IADJ

R_FS

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: SNVS901

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

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

7.4 Device Functional Modes........................................ 17

Application and Implementation ........................ 18

8.1 Application Information............................................ 18

8.2 Typical Application .................................................. 18

Power Supply Recommendation........................ 21

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

应用范围................................................................... 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....................................................... 4

6.3 Recommended Operating Conditions ...................... 4

6.4 Thermal Information.................................................. 4

6.5 Electrical Characteristics........................................... 5

6.6 Typical Characteristics.............................................. 6

Detailed Description .............................................. 8

7.1 Overview ................................................................... 8

7.2 Functional Block Diagram ......................................... 9

10 Layout................................................................... 22

10.1 Layout Guidelines ................................................. 22

10.2 Layout Example .................................................... 22

11 器件和文档支持 ..................................................... 23

11.1 商标....................................................................... 23

11.2 静电放电警告......................................................... 23

11.3 Glossary................................................................ 23

12 机械封装和可订购信息 .......................................... 23

4 修订历史记录

Changes from Original (March 2014) to Revision A

Page

•

已更正图形数字排序 ............................................................................................................................................................... 1

已更新器件信息表................................................................................................................................................................... 1

Changed Terminal to Pin........................................................................................................................................................ 3

TPS92511

www.ti.com.cn

ZHCSC49A –MARCH 2014–REVISED MAY 2014

5 Pin Configuration and Functions

DDA (SO THERMAL PAD) PACKAGE

8 PINS

(TOP VIEW)

VCC

PGND

IADJ

VIN

DIM

GND

Pin Functions

DESCRIPTION

NAME

NO.

DIM

PWM Dimming Control. Apply logic level PWM signal to this pin dims the LED string. This pin is internally pulled up.

Switching Frequency Setting. An external resistor R_FSconnecting the FS pin to ground programs the switching

frequency from 50 kHz to 500 kHz.

GND

IADJ

Analog Signal Ground.

Average LED Current Setting. An external resistor R_IADJconnecting the IADJ pin to ground programs the average

LED current.

Integrated MOSFET Drain. Internally connected to the drain of the integrated MOSFET. Connect this pin to the

output inductor and anode of the Schottky diode.

Power Ground. Must be connected to the GND pin for normal operation. The PGND and GND pins are not internally

shorted.

PGND

Internal Regulator Output. Typically regulated to 5.4 V. Connect a capacitor of larger than 1 µF between the VCC

and GND pins.

VCC

VIN

Input Voltage. Supply pin to the device. The input voltage range is from 4.5 V to 65 V.

Thermal Connection Pad. Connect to a ground plane for heat dissipation.

Thermal pad

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

6 Specifications

(1)

6.1 Absolute Maximum Ratings

Unless otherwise specified, T_J= T_A= 25°C

MIN

–0.3

NOM

MAX

UNIT

VIN to GND

VIN to GND (Transient)

LX to PGND

–0.3

Pin voltage range

Temperature range

LX to PGND (Transient)

–3(2ns)

–0.3

FS, IADJ to GND

DIM to GND

–0.3

VCC to GND

–0.3

Internally

limited

Operating junction temperature range, T_J

–40

°C

(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which

operation of the device is intended to be functional. For specified specifications and test conditions, see the Electrical Characteristics.

6.2 Handling Ratings

MIN

MAX

150

1.5

UNIT

°C

T_stg

Storage temperature range

-65

(1)

(2)

V_ESD

Human Body Model (HBM) ESD stress voltage

Charged Device Model (CDM) ESD stress voltage⁽³⁾

1.5

(1) Electrostatic discharge (ESD) to measure device sensitivity and immunity to damage caused by assembly line electrostatic discharges in

to the device.

(2) Level listed above is the passing level per ANSI, ESDA, and JEDEC JS-001. JEDEC document JEP155 states that 500-V HBM allows

safe manufacturing with a standard ESD control process.

(3) Level listed above is the passing level per EIA-JEDEC JESD22-C101. JEDEC document JEP157 states that 250-V CDM allows safe

manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

MIN

4.5

NOM

MAX

UNIT

V_IN

T_A

T_J

Supply voltage range

Operating free air temperature

Operating junction temperature

–40

-40

125

°C

6.4 Thermal Information

TPS92511

DDA

8 PINS

59.9

THERMAL METRIC⁽¹⁾

UNIT

R_θJA

Junction-to-ambient thermal resistance

R_θJCtop

R_θJB

Junction-to-case (top) thermal resistance

Junction-to-board thermal resistance

59.1

30.6

°C/W

ψ_JT

Junction-to-top characterization parameter

Junction-to-board characterization parameter

Junction-to-case (bottom) thermal resistance

11.0

ψ_JB

30.5

R_θJCbot

4.2

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

TPS92511

www.ti.com.cn

ZHCSC49A –MARCH 2014–REVISED MAY 2014

6.5 Electrical Characteristics

Unless otherwise specified, -40°C ≤ T_J= T_A≤ 125°C, V_IN= 48 V

PARAMETER

SYSTEM

CONDITIONS

MIN

TYP

MAX UNIT

I_IN-DIM-HIGH

I_IN-DIM-LOW

I_LX-OFF

VIN Operating Current

VIN Standby Current

LX Pin Current

4.5 V ≤ V_IN≤ 65 V, R_IADJ= 3 kΩ, V_DIM= High

4.5 V ≤ V_IN≤ 65 V, R_IADJ= 3 kΩ, V_DIM= Low

Main switch turned OFF, V_LX= V_IN= 65 V

V_FS= 4.6V, R_IADJ= 3 kΩ, T_A= 25°C

V_FS= 4.6V, R_IADJ= 3 kΩ

2.8

2.3

3.15

2.7

µA

0.1

1.0

484

477

502

249

149

520

528

262

268

160

166

V_FS= 4.6V, R_IADJ= 6 kΩ, T_A= 25°C

V_FS= 4.6V, R_IADJ= 6 kΩ

236

I_LED

Average LED Current

233

V_FS= 4.6V, R_IADJ= 10 kΩ, T_A= 25°C

V_FS= 4.6V, R_IADJ= 10 kΩ

138

133

V_IADJ

IADJ Pin voltage

1.224

0.85

0.44

1.25 1.278

V_DIM-ON

V_DIM-OFF

V_DIM-HYS

f_SW

DIM Pin Upper Threshold

DIM Pin Lower Threshold

DIM Pin Threshold Hysteresis

Switching frequency

V_DIMIncreasing

V_DIMDecreasing

1.0

1.25

325

500

250

R_FS= 20 kΩ

450

550 kHz

t_on(min)

Minimum On-time

400

INTERNAL REGULATOR

V_CC

VCC Regulated Output Voltage

C_VCC=1 µF, no load

C_VCC=1 µF, V_IN= 4.5V, 2 mA load

V_CCrising

4.7

3.7

5.4

4.1

6.0

V_CC-UVLO-ON

V_CC-UVLO-OFF

V_CC-UVLO-HYS

VCC UVLO Upper Threshold

VCC UVLO Lower Threshold

VCC UVLO Hysteresis

3.50

3.05

3.75

4.00

V_CCfalling

275

1.4

INTEGRATED MOSFET

R_LX

Resistance Across LX and GND

Main Switch Turned ON, T_A= 25°C

2.15

Ω

THERMAL SHUTDOWN

T_SD

Thermal shutdown temperature

Thermal shutdown hysteresis

T_JRising

T_JFalling

165

°C

T_SD-HYS

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

6.6 Typical Characteristics

Unless otherwise specified, all curves are taken at V_IN= 48V with configuration in the application circuit for driving 12 LEDs

with I_LED= 0.5A and f_SW= 300 kHz as shown in this datasheet, and T_A= 25°C.

2.8

2.6

2.4

2.2

LED string open

VCC externally loaded

DIM pin open, LED string open

DIM = High

DIM = Low

V_IN(V)

I_VCC(mA)

C001

C003

图 1. I_INvs V_IN

图 2. V_CCvs I_VCC

5.5

1.265

1.26

1.255

1.25

V_CCnot loaded externally

DIM pin open, LED string open

4.5

1.245

-50

100

150

V_IN(V)

Temperature (ºC)

C002

C008

图 3. V_CCvs V_IN

图 4. V_IADJvs Temperature

1.8

1.7

1.6

1.5

1.4

1.3

1.2

510

505

500

495

490

100

150

100

150

±50

Temperature (ºC)

C009

C010

图 5. R_LXvs Temperature

图 6. f_SWvs Temperature

TPS92511

www.ti.com.cn

ZHCSC49A –MARCH 2014–REVISED MAY 2014

Typical Characteristics (接下页)

Unless otherwise specified, all curves are taken at V_IN= 48V with configuration in the application circuit for driving 12 LEDs

with I_LED= 0.5A and f_SW= 300 kHz as shown in this datasheet, and T_A= 25°C.

505.0

504.0

503.0

502.0

501.0

500.0

499.0

498.0

497.0

496.0

495.0

252.5

252.0

251.5

251.0

250.5

250.0

249.5

249.0

248.5

248.0

247.5

100

150

100

150

±50

Temperature (ºC)

C011

C012

图 7. I_LEDat 500 mA vs Temperature

图 8. I_LEDat 250 mA vs Temperature

151.5

151.2

150.9

150.6

150.3

150.0

149.7

149.4

149.1

148.8

148.5

0.16

0.14

0.12

0.1

0.08

0.06

0.04

0.02

100

150

±50

Temperature (ºC)

V_IN(V)

C013

C014

图 9. I_LEDat 150 mA vs Temperature

图 10. I_INvs V_INat LED Short

500

400

300

200

100

0.2

0.4

0.6

0.8

Dimming ratio (%)

C015

C016

图 11. PWM Dimming Linearity (0-100%) (f_SW= 500kHz, L1 =

图 12. PWM Dimming Linearity (under 1%) (f_SW= 500kHz, L1

68 µH

= 68 µH

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

7 Detailed Description

7.1 Overview

The TPS92511 is an easy to use constant current buck converter for driving a single LED string with current up

to 0.5A and efficiency up to 95%. Only 5 external components are required for basic operation and single layer

PCB layout is feasible because of the integration of a N-MOSFET, no external current sensing resistor, no

external compensation and the proper pin assignment. A high-value external resistor programs the LED current

so that fine tuning of the LED current can be achieved. Another high-value external resistor programs a constant

switching frequency from 50kHz to 500kHz. As a result of constant switching frequency, EMI design becomes

easy. The TPS92511 provides a wide input voltage range from 4.5V to 65V. By adding simple external circuits,

it can handle applications with even higher input voltages.

The TPS92511 employs a proprietary Pulse-Level-Modulation (PLM) control scheme under continuous

conduction mode (CCM) to regulate the LED current without the need of sensing the LED current directly. It

applies a floating buck topology with a low-side N-channel power MOSFET, which does not need boot-strapping

capacitor, so that driving LED string under drop-out conditions and very high input voltages are feasible. For

multiple channel systems, the floating buck topology without external current sensing network together with the

proprietary control scheme allows a common-anode connection of the LED strings without external current

sensing network. This saves high-side current sensing wirings for separate driver boards and LED board

systems and significantly reduces the number of wiring, which can lower overall manufacturing cost.

The TPS92511 has very fast PWM dimming response time. There is almost no delay between the DIM pin

voltage rising edge and the start of the LED current conduction, so it can dim down to nearly zero current. In

order to maintain good dimming linearity, the minimum LED current pulse width is suggested to be three

switching cycles. For example, if the switching frequency is 500 kHz, the minimum DIM pulse width is 6µs and

the dimming frequency is 150Hz, a contrast ratio of more than 1000:1 can be achieved.

TPS92511

www.ti.com.cn

ZHCSC49A –MARCH 2014–REVISED MAY 2014

7.2 Functional Block Diagram

VIN

V_CC

Voltage

Regulator

VCC

Clock

Generator

Pulse Ref.

UVLO

V_CC

Switch

Control logic

3.75V

RISNS

V_CC

VCC

DIM

1.0V

Pulse Ref.

Current Mirror

Slope Comp.

PLM module

1.25V

IADJ

PGND

GND

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

7.3 Feature Description

7.3.1 Pulse Level Modulation (PLM) Control

A proprietary Pulse-Level-Modulation (PLM) control method is used in the TPS92511. It can regulate the

average LED current by sensing only the inductor current at the on-period (图 13). The integrated MOSFET and

the sensing and control circuits in the TPS92511 implement the whole PLM control internally so the control does

not suffer from tolerance and noise issues that may be coming from external components. As compared with the

conventional method which regulates average LED current by sensing the current over the entire switching cycle,

the power dissipation on the sensing circuit in PLM is much lower. For example, consider a duty cycle of 0.5, the

power dissipation on current sensing in PLM can be reduced by half. PLM requires no external loop

compensation circuit. Besides, the accuracy of the regulated LED current is high (typically ±3.5% in the

TPS92511).

LED(avg)

1/f

SW .

Time

图 13. Waveforms of a Floating Buck LED Driver with PLM

7.3.2 Pulse Level Modulation (PLM) Operaion Principles

The Pulse-Level-Modulation is a patented method to ensure an accurate average output current regulation

without the need of direct output current sensing. 图 13 shows the current waveforms of a typical buck converter

under steady state, where, I_L1is the inductor current and I_LXis the current flowing into the LX pin. For a buck

converter operating in steady state, the mid-point of the RAMP portion of I_L1equals to the average value of I_L1

and hence the average LED current I_LED(avg). In short, by regulating the mid-point with respect to a precise

reference level, PLM achieves LED current regulation by sensing the main MOSFET current solely, instead of

the entire cycle of I_L1.

7.3.3 PLM Control enable Common-Anode Low-Side Sensing (CALS)Technique to Save Wiring

For multi-channel systems with separated driver boards and LED array boards, the Pulse-Level-Modulation

(PLM) control scheme enable Common-Anode Low-Side Current Sensing to save inter-board wirings. 图 14

shows a conventional configuration with a Low-side switching and High-Side Current Sensing. For an n channel

system with separated driver and an LED array boards, 2n inter-board wirings are required. For example, an

128-channel system needs 256 inter-board wirings, which implies a high material and manufacturing cost. 图 15

shows the PLM configuration with Low-side switching and Low-Side Current Sensing. A Common-Anode

configuration is used for the LED array board. As shown in the figure, an n channel system with separated driver

and LED array boards requires only n+1 inter-board wirings. For an 128-channel system, only 129 inter-board

wirings are required. The wiring cost is cut by half, and the cost of the end product can be reduced.

TPS92511

www.ti.com.cn

ZHCSC49A –MARCH 2014–REVISED MAY 2014

Feature Description (接下页)

LED String

LED array board

LED driver board

Sensing

resistor 1

Sensing

resistor 2

Sensing

resistor n

LED Driver n

LED Driver 1

LED Driver 2

V_IN

图 14. Conventional Configuration with Low-Side Switching and High-Side Current Sensing Requires 2×n

Inter-Board Wirings

LED String

LED array board

LED driver board

LED Driver n

LED Driver 1

LED Driver 2

V_IN

图 15. PLM Configuration with Common-Anode Low-Side Switching Requires n+1 Inter-Board Wirings

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

Feature Description (接下页)

7.3.4 Internal Regulator

The TPS92511 integrates an internal voltage regulator for powering internal circuitry. For stability, an external

capacitor C_VCCof at least 1 μF should be connected between the VCC and PGND pins The output of the internal

regulator V_CCis 5.4V when V_INis larger than 6V. If V_INis lower than 6V, V_CCdecreases. The TPS92511 will

trigger the VCC under-voltage lock-out if V_CCfalls below typically 3.5V. V_CCcan be used to bias external circuits

subject to a loading of maximum 2 mA, while it has a short circuit current limit at typically 16 mA.

7.3.5 Setting The Switching Frequency

The switching frequency f_SWof the TPS92511 is programmable in the range of 50 kHz to 500 kHz by a single

resistor R_FSconnecting the FS pin and ground. The following equation shows the relationship between f_SWand

R_FS

10 u10

kHz

(1)

图 16 plots f_swagainst R_FS. 表 1 shows values of R_FSfor commonly used switching frequencies.

500

450

400

350

300

250

200

150

100

20 40 60 80 100 120 140 160 180 200

R_FS(k:)

C006

图 16. Switching Frequency vs R_FS

表 1. Commonly Used f_SWAnd R_FS

f_SW(kHz)

R_FS(kΩ)

200

100

300

33.2

500

7.3.6 Setting The LED Current

The LED current I_LEDof the TPS92511 is programmable by a single resistor R_IADJconnecting the IADJ pin and

ground. The IADJ pin is internally biased to 1.25 V. 公式 2 shows the relationship between I_LEDand R_IADJ

1500

LED

IADJ

(2)

To ensure stability, R_IADJmust be less that 30 kΩ, implying a minimum I_LEDof 50 mA can be programmed. The

tolerance of I_LEDof 150 mA is shown in the ELECTRICAL CHARACTERISTICS. Larger tolerance should be

expected for lower I_LED. 图 17 plots I_LEDagainst R_IADJ. 表 2 shows values of R_IADJfor commonly used I_LED

TPS92511

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ZHCSC49A –MARCH 2014–REVISED MAY 2014

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

R_IADJ(k:)

C007

图 17. LED Current vs

RIADJ

表 2. Commonly Used I_LEDAnd R_IADJ

I_LED(mA)

150

R_IADJ(kΩ)

350

4.32

500

3.01

7.3.7 Integrated MOSFET

The TPS92511 integrates a N-channel power MOSFET, the drain of which is connected to the LX pin. When the

integrated MOSFET is turned on, the resistance across the LX and GND pins is typically 1.4Ω. The integrated

MOSFET has a fixed current limit of 1.2A to protect the application circuit during critical operation conditions like

short circuit of the LED string. Once the limit is hit, the integrated MOSFET turns off immediately for 34 µs to let

the inductor discharge.

The minimum on-time of the integrated MOSFET is 400 ns. It may be hit at a high switching frequency and a

high V_IN/V_LEDratio. Once hit, the I_LEDregulation may be affected. In the worst case, I_LEDmay be boost up to a

level higher than the programmed value, and the LED string and/or the inductor may be damaged as a result.

Hence, it is recommened that the ratio between V_INand V_LEDshould be designed under the following constraint:

V_LED

t 400nsu f_SW

(3)

7.3.8 Inductor Selection

Operating in the continuous conduction mode (CCM) is required in the TPS92511 application circuit. In the CCM,

considering the on-period, the peak-to-peak inductor current ripple (2ΔI_L1) is shown in 公式 4.

ꢀ

ꢂ V

ꢁ

on IN

LED

2'I

(4)

(5)

Because

LED

on SW

L₁can be a function of V_IN, V_LED, f_SWand ΔI_L1as shown in 公式 6 .

ꢂ V_LEDV_LED

2'I_L1V_INf_SW

ꢀ

ꢁ

L₁

(6)

The value of L₁is selected by designers with the consideration of all above parameters. The minimum L₁

calculated by the following equation is a good starting point for designing L₁:

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

R_FSR_IADJ

L₁! 1PH:^ꢀ1

10⁶

(7)

The following table shows some typical examples of using R_FSand R_IADJto estimate the minimum L₁:

表 3. Estimation Of Minimum L₁Using R_FSAnd R_IADJ

Estimated Minimum L₁

R_FS(kΩ)

R_IADJ(kΩ)

Recommended L₁(µH)

(µH)

1000

100

33.2

1000

100

3.01

4.32

3.01

To maintain the CCM, ΔI_L1must be smaller than the average LED current I_LED(avg). Hence, the minimum

inductance used is:

ꢀ

ꢂ V

ꢁ

LED LED

1(min)

V f

LED(avg) IN SW

(8)

In the absence of output capacitors, the TPS92511 can maintain a continuous I_LEDthroughout the entire

switching cycle because in such case the inductor current is the same as I_LED(floating buck topology operating in

the CCM). However, the LED peak current must not exceed the rated current of the LED. The peak LED current

can be found by the following equation:

ꢀ

_INꢂ V_LED

2L₁V_INf_SW

ꢁ

V_LED

I_LED(peak) I_LED(avg)

ꢃ

(9)

7.3.9 Integrated MOSFET Current Limit

The current limit of the integrated MOSFET is internally fixed at 1.2A to protect the LED string, the inductor and

the integrated MOSFET from overdriven. Once triggered, the integrated MOSFET turns off immediately for 34 µs

to let the inductor to discharge. The triggering of the current limit cycles repetitively until all overdriven conditions

disappear.

7.3.10 PWM Dimming Control

The TPS92511 implements PWM dimming by applying a PWM dimming signal to the DIM pin. A low input

applying to the DIM pin disables the switching of the integrated MOSFET, and as a result discharges the inductor

and then turns off the LED string. To turn on the LED string, the DIM pin should be connected to high or left open

(since it is internally pulled high by a current of typically 40 µA and 90 µA when the DIM pin is low and high

respectively). The PWM dimming frequency is recommended to be lower than 0.1f_SWto ensure normal operation.

7.3.11 Analog Dimming

Analog dimming can be implemented by injecting a current to R_IADJ(图 18) and as a result reduces the current of

the IADJ pin, I_ADJ, which is controlled internally by the TPS92511 to bias the voltage on the IADJ pin to be

1.25V. If the CCM can be maintained, the minimum I_ADJcan achieve 15 µA, which refers to an I_LEDof 18 mA. If

I_ADJis further decreased, I_LEDmay not follow due to the presence of the minimum on-time of the integrated

MOSFET. If the CCM cannot be maintained, I_LEDcan still decrease monotonically with I_ADJ. However, if good

line and load regulations are required, the CCM should be maintained by using a large inductance.

TPS92511

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ZHCSC49A –MARCH 2014–REVISED MAY 2014

V_IN

4.5V-

65VDC

TPS92511

VCC

VIN

LED string

I_LED

C_VCC

C_IN

PGND

IADJ

I_ADJ

DIM

PWM dimming signal

R_ADIM

R_IADJ

GND

R_FS

V_ADIM

图 18. Circuit Configuration for Analog Dimming

7.3.12 High Voltage Buck Configuration

The TPS92511 can handle applications with an input voltage higher than 65V, which is the maximum V_INof the

recommended operating condition of the TPS92511, by adding an external high voltage N-channel MOSFET to

the application circuit as shown in 图 19. PWM dimming can be implemented in this circuit without additional

efforts, and analog dimming is also feasible by referencing to additional circuits shown in 图 18.

V_SUPPLY

High

Voltage

High Voltage

Switching

Diode

V_BIAS

LED string

I_LED

8V-25VDC

TPS92511

High Voltage

N-MOSFET

C_IN

VCC

VIN

C_VCC

PGND

IADJ

DIM

PWM dimming signal

R_IADJ

GND

R_FS

图 19. Circuit Configuration for Very High Voltage Buck

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

7.3.13 Thermal Foldback

Thermal foldback is useful to prevent over-temperature of LEDs during operation by sensing the temperature of

LEDs and, if the sensed temperature is high, reducing I_LEDto decrease the power and as well as the temperature

of LEDs. Thanks to the feature of analog dimming, thermal foldback can be implemented by embedding a

negative temperature coefficient (NTC) resistor, R_NTC, into a circuit as shown in 图 20. When the sensed

temperature increases, R_NTCdecreases and thus the emitter current of Q_T1increases to reduce I_LEDby means of

analog dimming. The resistor R_TFcan adjust the loop gain of the thermal foldback control loop, which should be

high enough to avoid oscillation and maintain stability.

V_IN

4.5V-

65VDC

TPS92511

VCC

VIN

LED string

I_LED

C_VCC

R_NTC

C_IN

PGND

IADJ

I_ADJ

DIM

Q_T1

PWM dimming signal

R_IADJ

GND

R_T1

R_TF

R_FS

图 20. Circuit Configuration for Thermal Foldback

7.3.14 EMI Consideration

Conductive and radiative EMI can be major concerns for lighting applications. The TPS92511 application circuit

can be designed for the EN 55022 class B standard by adding a few external components, as shown in 图 21.

The input filter which consists of an inductor L₂and two capacitors C_IN2and C_IN3takes care of the conductive

EMI, while the output capacitor C_LEDand the ferrite bead FB₁which inserts between the LX pin and D₁take care

of the radiative EMI.

Input EMI filter

V_IN

48V

10 PH

100V

LED

TPS92511

LED

IN2

IN3

1 PF

50V

2.2 PF

100V

VCC

VIN

100:ꢀ@

100 MHz

PGND

IADJ

100 PH

PWM

DIM

dimming

signal

VCC

1PF

16V

GND

IADJ

3.01 k:

33.2 k:

图 21. Circuit Configuration with EMI Design Consideration

TPS92511

www.ti.com.cn

ZHCSC49A –MARCH 2014–REVISED MAY 2014

7.4 Device Functional Modes

7.4.1 Operation with V_IN< 4.5 V (minimum V_IN)

For the typical application circuit, when the input voltage drops so that the VCC voltage regulator is under drop-

out mode, and the VCC voltage drops below the “VCC UVLO Lower Threshold” (typically 3.48V), the switching of

the main MOSFET is stopped, and the LED current will become zero. At the same time, the voltages of both the

FS and IADJ pins will become zero .

When the input voltage increases from zero and the VCC voltage is increased to cross over the “VCC UVLO

Upper Threshold” (typically 3.75V), the voltages on the FS and IADJ pins will rise to their regulation voltage

(typically 1.25V), the switching of the main MOSFET is started upon the DIM pin voltage is HIGH, and the LED

current will ramp up to its preset value set by R_IADJ

7.4.2 Operation with DIM control

For the typical application circuit, when the VCC voltage is not under UVLO condition, the switching of the main

MOSFET is enabled and the LED current is conducted if the DIM pin voltage is higher than the “DIM Pin Upper

Threshold” (typically 1V).

Alternaltively, the switching is disabled and the LED current is cut off if the voltage of the DIM pin is lower than

the “DIM Pin Lower Threshold” (typically 0.675V).

7.4.3 Linear Mode

When the VCC voltage is not under UVLO condition and the voltage on the FS pin is forced to be higher than

4.2V but lower than 5V, the switching of the main MOSFET is disabled, and the TPS92511 is working in the

Linear Mode. In the Linear Mode, if the voltage on the DIM pin is higher than the “DIM Pin Upper Threshold”

(typically 1V), the TPS92511 will regulate the LX pin in-going current according to the preset value set by R_IADJ

Alternatively, if the voltage on the DIM pin is lower than the “DIM Pin Lower Threshold” (typically 0.675V), the LX

pin will open and its in-going current will become zero.

Below is the simple configuration to have the TPS92511 working as a linear current shunt regulator.

V_IN

4.5V-

65VDC

TPS92511

V_CC

LED string

I_LED

VCC

VIN

C_IN

C_VCC

PGND

IADJ

GND

PWM dimming signal

DIM

V_CC

1 k:

R_IADJ

sharp

knee

point

图 22. Circuit Configuration for Working as a Linear Current Shunt Regulator

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

8 Application and Implementation

8.1 Application Information

The TPS92511 is an LED driver which provides a regulated output current to drive a single string of LED with the

forward voltage lower than the input voltage. The following procedures design a TPS92511 application circuit

with an input voltage of 48V, driving an LED string of 38V at an LED current of 0.5A. The switching frequency is

300 kHz.

8.2 Typical Application

8.2.1 TPS92511 LED driver for 12 LEDs at 0.5A

V_IN

48V

LED

TPS92511

100V

2.2 PF

100V

VCC

VIN

PGND

IADJ

100 PH

PWM

dimming

signal

DIM

VCC

1PF

16V

GND

IADJ

3.01 k:

33.2 k:

图 23. Application Circuit of TPS92511 (f_SW= 300 kHz and I_LED= 0.5A)

TPS92511

www.ti.com.cn

ZHCSC49A –MARCH 2014–REVISED MAY 2014

Typical Application (接下页)

8.2.1.1 Design Requirements

表 4. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

Input voltage range

LED current

43V to 53V

0.5A

LED string forward voltage

Operating frequency

38V

300 kHz

8.2.1.2 Detailed Design Procedure

C_IN: The function of the input capacitor C_INis to reduce the input voltage ripple. Ceramic capacitors are

recommended owing to the concern of product lifetime. A 100V 2.2 µF ceramic capacitor is selected in this

circuit.

C_VCC: The capacitor on the VCC pin provides noise filtering and stabilizes the internal regulator. It also prevents

false triggering of the VCC UVLO. C_VCCis recommended to be a 1 μF good quality and low ESR ceramic

capacitor.

D₁: The diode D₁should have a reverse voltage larger than V_INin the floating buck topology. In this circuit, a

100V diode is selected.

R_FSand R_IADJ: In this circuit, the switching frequency and LED current are designed to be 300 kHz and 0.5A.

From 表 1 and 表 2, R_FSis 33.2 kΩ and R_IADJis 3.01 kΩ.

L₁: The selection of inductor mainly affects the inductor current ripple. In this circuit, we design the peak to peak

inductor current ripple to be 50% of I_LED, i.e. 0.25A. From (6), L₁is calculated to be 106 µH, and a 100 µH

inductor is selected.

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

8.2.1.3 Application Curves

100

1 LEDs

3 LEDs

7 LEDs

10 LEDs

12 LEDs

19 LEDs

1 LEDs

3 LEDs

7 LEDs

10 LEDs

12 LEDs

19 LEDs

-1

-2

-3

-4

-5

V_IN(V)

C004

C005

图 24. Efficiency vs V_IN

图 25. LED Current Regulation vs V_IN

V_IN

V_LX

I_LED

图 26. Steady State Operation

图 27. Power Up

V_DIM

V_LX

I_LED

图 28. PWM Dimming (V_DIMRising)

图 29. PWM Dimming (V_DIMFalling)

TPS92511

www.ti.com.cn

ZHCSC49A –MARCH 2014–REVISED MAY 2014

V_DIM

V_LX

I_LED

图 31. PWM Dimming (9 µs dimming pulse) (f_SW= 500kHz,

图 30. PWM Dimming (f_DIM= 1 kHz, 50% Duty Cycle)

L₁= 68 µH)

9 Power Supply Recommendation

This device is designed to operate from an input voltage supply range between 4.5 V and 65 V. The input supply

should be well regulated. If the input supply is located more than a few inches from the TPS92511 application

board, additional bulk capacitance may be required in addition to the input capacitor. A ceramic capacitor with a

value of 2.2 μF is a typical choice.

TPS92511

ZHCSC49A –MARCH 2014–REVISED MAY 2014

www.ti.com.cn

10 Layout

10.1 Layout Guidelines

•

The PCB layout of the TPS92511 application circuit plays an important role in optimizing the performance.

The external components should be placed as close to the TPS92511 as possible to minimize resistance and

parasitic inductance of copper traces.

•

For example, D₁and L₁should be near the LX pin, and C_VCCshould be near the VCC pin, and the connecting

copper traces are short and thick.

The exposed pad of the TPS92511, which is internally connected to the die substrate, should be connect to a

ground plane, and the plane should be extended as much as possible on the same copper layer around the

TPS92511.

•

Using numerous vias beneath the exposed pad to dissipate heat to another copper layer is also a good

practice.

10.2 Layout Example

LED-

VIN, LED+

GND

C_IN

L₁

D₁

C_VCC

DIM

R_IADJ

R_FS

图 32. TPS92511 Board Layout

10.2.1 Thermal Consideration

Ψ_JT(shown in session 6.4 Thermal Information) is a relatively small value for package with exposed pad since

most of the heat is dissipated through the exposed pad to the copper plate of the PCB (assuming optimized PCB

layout), relatively little heat goes to the top of the device. The top of the device mold compound temperature is

physically close to the device junction temperature.

For example, a 30W output TPS92511 end system at 95% power efficiency (can be estimated from the efficiency

curves of Figure 13), power loss is 1.6W. Assuming all the heat is generated from the TPS92511 (which is true

for high V_LED), and assuming half of the heat generated is dissipated through the top of the device. Now Ψ_JTis

11 °C/W, the device junction temperature is estimated to be higher than the package’s top-surface temperature

by 11 x 1.6 x 0.5 = 8.8 (°C). If the package top-surface temperature is measured to be 90 °C (for example by an

IR camera), the device junction temperature is around 99 °C, which is within the 125°C maximum junction

temperature requirement with margin.

TPS92511

www.ti.com.cn

ZHCSC49A –MARCH 2014–REVISED MAY 2014

11 器件和文档支持

11.1 商标

All trademarks are the property of their respective owners.

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 Glossary

SLYZ022 — TI Glossary.

This glossary lists and explains terms, acronyms and definitions.

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。

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PACKAGE OPTION ADDENDUM

www.ti.com

10-Dec-2020

PACKAGING INFORMATION

Orderable Device

Status Package Type Package Pins Package

Eco Plan

Lead finish/

Ball material

MSL Peak Temp

Op Temp (°C)

Device Marking

Samples

Drawing

Qty

(1)

(2)

(3)

(4/5)

(6)

TPS92511DDA

ACTIVE SO PowerPAD

DDA

RoHS & Green

Level-3-260C-168 HR

-40 to 125

92511

TPS92511DDAR

2500 RoHS & Green

⁽¹⁾The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

⁽²⁾RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance

do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may

reference these types of products as "Pb-Free".

RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.

Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based

flame retardants must also meet the <=1000ppm threshold requirement.

⁽³⁾MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

⁽⁴⁾There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

⁽⁵⁾Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation

of the previous line and the two combined represent the entire Device Marking for that device.

(6)

Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two

lines if the finish value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information

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Addendum-Page 2

重要声明和免责声明

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TPS92511DDA [TI]

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