LM3648TTYFFR [TI]
具有 1.5A 高侧电流源的 LM3648 同步升压 LED 闪光灯驱动器 | YFF | 12 | -40 to 85;
| 型号： | LM3648TTYFFR |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 具有 1.5A 高侧电流源的 LM3648 同步升压 LED 闪光灯驱动器 | YFF | 12 | -40 to 85 驱动 闪光灯 接口集成电路 驱动器 |
| 文件： | 总35页 (文件大小：1036K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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LM3648
ZHCSD27 –OCTOBER 2014
LM3648 具有 1.5A 高侧电流源的同步升压 LED 闪光灯驱动器
1 特性
3 说明
1
•
1.5A LED 电流源可编程性
精确的可编程 LED 电流范围为 1.954mA 至 1.5A
LM3648 是一款 LED 闪光灯驱动器，其采用小型解决
方案尺寸，并且具备更强的适应能力。 LM3648 采用
2MHz 或 4MHz 固定频率的同步升压转换器为 1.5A
LED 恒流源供电。 自适应调节方法确保电流源保持可
调节状态，并且最大限度地提高效率。
•
•
优化了低电池电压条件下的闪存 LED 电流（输入
电压闪存监控器 (IVFM)）
•
在火炬模式 (@ 100mA) 和闪存模式（@1A 至
1.5A）下效率超过 85%
LM3648 的功能通过 I2C 兼容接口进行控制。 其功能
包括：硬件闪光灯和硬件手电筒引脚（STROBE 和
TORCH/TEMP）、TX 中断以及 NTC 热敏电阻监视
器。 该器件在闪光灯模式下可提供 64 种电流，在摄
像模式（手电筒）下可提供 128 种电流。
•
•
•
•
•
•
•
支持阴极接地 LED 操作，改进了热管理
小型解决方案尺寸：< 16mm2
硬件选通使能 (STROBE)
射频功率放大器脉冲事件的同步输入 (TX)
硬件火炬使能 (TORCH/TEMP)
远程 NTC 监控 (TORCH/TEMP)
400kHz I2C 兼容接口
而且还提供有 2MHz 或 4MHz 开关频率选项、过压保
护 (OVP) 功能以及可调限流功能，允许使用微型、超
薄的电感器和 (10μF) 陶瓷电容。 该器件的工作环境温
度范围为 -40°C 至 85°C。
–
LM3648（I2C 地址 = 0x63）
2 应用
器件信息(1)
可拍照手机白色 LED 闪光灯
器件型号
LM3648
封装
封装尺寸（最大值）
芯片级球状引脚
栅格阵列
1.69mm x 1.31mm
(DSBGA) (12)
(1) 要了解所有可用封装，请见数据表末尾的可订购产品附录。
简化电路原理图
L1
1 PH
LM3648
IN
SW
VIN
2.5V t 5.5V
C1
10 PF
HWEN
SDA
OUT
C2
10 PF
SCL
PP/PC
STROBE
LED
D1
TORCH/
TEMP
TX
GND
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: SNVSA68
LM3648
ZHCSD27 –OCTOBER 2014
www.ti.com.cn
目录
7.4 Device Functioning Modes...................................... 13
7.5 Programming........................................................... 16
7.6 Register Descriptions.............................................. 18
Applications and Implementation ...................... 22
8.1 Application Information............................................ 22
8.2 Typical Application ................................................. 22
Power Supply Recommendations...................... 27
1
2
3
4
5
6
特性.......................................................................... 1
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 ...................................................... 4
6.3 Recommended Operating Conditions....................... 4
6.4 Thermal Information.................................................. 4
6.5 Electrical Characteristics........................................... 5
6.6 Timing Requirements ............................................... 5
6.7 Switching Characteristics.......................................... 5
6.8 Typical Characteristics.............................................. 6
Detailed Description ............................................ 10
7.1 Overview ................................................................. 10
7.2 Functional Block Diagram ...................................... 11
7.3 Feature Description ................................................ 11
8
9
10 Layout................................................................... 27
10.1 Layout Guidelines ................................................. 27
10.2 Layout Example ................................................... 28
11 器件和文档支持 ..................................................... 29
11.1 器件支持................................................................ 29
11.2 文档支持................................................................ 29
11.3 商标....................................................................... 29
11.4 静电放电警告......................................................... 29
11.5 术语表 ................................................................... 29
12 机械封装和可订购信息 .......................................... 29
7
4 修订历史记录
日期
修订版本
注释
2014 年 10 月
*
最初发布。
2
Copyright © 2014, Texas Instruments Incorporated
LM3648
www.ti.com.cn
ZHCSD27 –OCTOBER 2014
5 Pin Configuration and Functions
DSBGA (YFF)
12 Pins
Top View
Top View
A1
B1
A2
B2
A3
B3
Pin A1
C2
D2
C1
D1
C3
D3
Pin Functions
PIN
TYPE(1)
DESCRIPTION
NUMBER
NAME
A1
GND
G
P
Ground
Input voltage connection. Connect IN to the input supply and bypass to GND with a
10-µF or larger ceramic capacitor.
A2
IN
A3
B1
SDA
SW
I/O
P
Serial data input/output in the I2C Mode on LM3648.
Drain Connection for Internal NMOS and Synchronous PMOS Switches.
Active high hardware flash enable. Drive STROBE high to turn on Flash pulse.
Internal pulldown resistor of 300 kΩ between STROBE and GND.
B2
B3
C1
STROBE
SCL
I
I
Serial clock input for LM3648.
Step-up DC/DC CONVERTER Output. Connect a 10-µF ceramic capacitor between
this terminal and GND.
OUT
P
Active high enable pin. High = Standby, Low = Shutdown/Reset. Internal pulldown
resistor of 300 kΩ between HWEN and GND.
C2
HWEN
I
Torch terminal input or threshold detector for NTC temperature sensing and current
scale back.
C3
D1
D2
D3
TORCH/TEMP
I/P
P
I
LED
TX
High-side current source output for flash LED. Connect pin D1 to D3 externally.
Configurable dual polarity power amplifier synchronization input. Internal pulldown
resistor of 300 kΩ between TX and GND.
LED
P
High-side current source output for flash LED. Connect pin D1 to D3 externally.
(1) A: Analog Pin, G: Ground Pin, P: Power Pin, I: Digital Input Pin
Copyright © 2014, Texas Instruments Incorporated
3
LM3648
ZHCSD27 –OCTOBER 2014
www.ti.com.cn
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN
MAX
UNIT
IN, SW, OUT, LED
−0.3
6
V
SDA, SCL, TX, TORCH/TEMP, HWEN, STROBE
−0.3 to the lesser of
(VIN+0.3) w/ 6 V max
Continuous power dissipation(3)
Internally limited
150
Junction temperature (TJ-MAX
)
°C
Maximum lead temperature (soldering)
See(4)
(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) All voltages are with respect to the potential at the GND terminal.
(3) Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ = 150°C (typ.) and
disengages at TJ = 135°C (typ.). Thermal shutdown is ensured by design.
(4) For detailed soldering specifications and information, please refer to Texas Instruments Application Note 1112: DSBGA Wafer Level
Chip Scale Package (SNVA009).
6.2 Handling Ratings
MIN
MAX
UNIT
Tstg
Storage temperature range
−65
150
°C
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all
pins(1)
−2500
−1500
2500
1500
V(ESD)
Electrostatic discharge
V
Charged device model (CDM), per JEDEC specification
JESD22-C101, all pins(2)
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN
MAX
5.5
UNIT
VIN
2.5
−40
−40
V
Junction temperature (TJ)
Ambient temperature (TA)
125
85
°C
(3)
(1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) All voltages are with respect to the potential at the GND terminal.
(3) In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may
have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP
=
125°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to-ambient thermal resistance of the
part/package in the application (RθJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (RθJA × PD-MAX).
6.4 Thermal Information
LM3648
THERMAL METRIC(1)
DSBGA (YFF)
12 PINS
90.2
UNIT
RθJA
RθJC(top)
RθJB
ΨJT
Junction-to-ambient thermal resistance
°C/W
°C/W
°C/W
°C/W
°C/W
Junction-to-case (top) thermal resistance
Junction-to-board thermal resistance
0.5
40.0
Junction-to-top characterization parameter
Junction-to-board characterization parameter
3.0
ΨJB
39.2
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
4
Copyright © 2014, Texas Instruments Incorporated
LM3648
www.ti.com.cn
ZHCSD27 –OCTOBER 2014
6.5 Electrical Characteristics
Typical limits tested at TA = 25°C. Minimum and maximum limits apply over the full operating ambient temperature range
(−40°C ≤ TA ≤ 85°C). Unless otherwise specified, VIN = 3.6 V, HWEN = VIN.(1)(2)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
CURRENT SOURCE SPECIFICATIONS
VOUT = 4 V, flash code = 0x3F = 1.5 A
flash
–7%
1.5
7%
A
ILED
Current source accuracy
VOUT = 4 V, torch code = 0x3F = 178.6 mA
torch
–10%
178.6
10%
mA
ILED = 1.5 A
Flash
Torch
290
158
5
LED current source regulation
voltage
VHR
mV
V
ILED = 178.6 mA
ON threshold
OFF threshold
4.86
4.75
5.1
VOVP
4.88
4.99
STEP-UP DC/DC CONVERTER SPECIFICATIONS
RPMOS
RNMOS
PMOS switch on-resistance
NMOS switch on-resistance
86
65
mΩ
Reg 0x07, bit[0] = 0
Reg 0x07, bit[0] = 1
Falling VIN
–12%
–12%
–2%
1.9
2.8
2.5
0.6
50
12%
12%
2%
ICL
Switch current limit
A
VUVLO
VTRIP
INTC
Undervoltage lockout threshold
NTC comparator trip threshold
NTC current
V
V
Reg 0x09, bits[3:1] = '100'
–5%
5%
–6%
6%
µA
Input voltage flash monitor trip
threshold
VIVFM
IQ
Reg 0x02, bits[5:3] = '000'
–3%
2.9
0.3
0.1
3%
0.75
4
V
Quiescent supply current
Device not switching pass mode
mA
µA
Device disabled, HWEN = 0 V
2.5 V ≤ VIN ≤ 5.5 V
ISD
Shutdown supply current
Device disabled, HWEN = 1.8 V
2.5 V ≤ VIN ≤ 5.5 V
ISB
Standby supply current
2.5
10
µA
HWEN, TORCH/TEMP, STROBE, TX VOLTAGE SPECIFICATIONS
VIL
VIH
Input logic low
Input logic high
0
0.4
VIN
2.5 V ≤ VIN ≤ 5.5 V
V
1.2
I2C-COMPATIBLE INTERFACE SPECIFICATIONS (SCL, SDA)
VIL
Input logic low
Input logic high
Output logic low
0
0.4
VIN
2.5 V ≤ VIN ≤ 4.2 V
V
VIH
VOL
1.2
ILOAD = 3 mA
400
mV
(1) All voltages are with respect to the potential at the GND pin.
(2) Minimum (Min) and Maximum (Max) limits are specified by design, test, or statistical analysis. Typical (typ.) numbers are not verified, but
do represent the most likely norm. Unless otherwise specified, conditions for typical specifications are: VIN = 3.6 V and TA = 25°C.
6.6 Timing Requirements
MIN
2.4
100
0
NOM
MAX
UNIT
t1
t2
t3
t4
t5
SCL clock period
µs
Data in set-up time to SCL high
Data out stable After SCL low
SDA low set-up time to SCL low (start)
SDA high hold time after SCL high (stop)
ns
100
100
6.7 Switching Characteristics
over operating free-air temperature range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
2.5 V ≤ VIN ≤ 5.5 V
MIN
–6%
TYP
MAX
6%
UNIT
ƒSW
Switching frequency
4
MHz
Copyright © 2014, Texas Instruments Incorporated
5
LM3648
ZHCSD27 –OCTOBER 2014
www.ti.com.cn
t
1
SCL
SDA_IN
t
t
5
4
t
2
SDA_OUT
t
3
Figure 1. I2C-Compatible Interface Specifications
6.8 Typical Characteristics
Ambient temperature is 25°C, input voltage is 3.6 V, HWEN = VIN, CIN = COUT = 2 × 10 µF and L = 1 µH, unless otherwise
noted.
1.6
1.4
1.2
1
0.4
0.36
0.32
0.28
0.24
0.2
TA = -40°C
TA = +25°C
TA = +85°C
TA = -40°C
TA = +25°C
TA = +85°C
0.8
0.6
0.4
0.2
0
0.16
0.12
0.08
0.04
0
0
16
32
48
64
80
96
112
128
0
16
32
48
64
LED Code (dec#)
LED Code (dec#)
D015
D001
Figure 3. LED Torch Current vs Brightness Code
Figure 2. LED Flash Current vs Brightness Code
1.62
1.6
1.62
1.6
TA = -40qC
TA = +25qC
TA = +85qC
TA = -40qC
TA = +25qC
TA = +85qC
1.58
1.56
1.54
1.52
1.5
1.58
1.56
1.54
1.52
1.5
1.48
1.46
1.44
1.42
1.4
1.48
1.46
1.44
1.42
1.4
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
VIN (V)
D022
D021
ƒSW = 4 MHz
Flash
ƒSW = 2 MHz
Brightness Code = 0x3F
Flash
Brightness Code = 0x3F
Figure 5. LED Current vs Input Voltage
Figure 4. LED Current vs Input Voltage
6
Copyright © 2014, Texas Instruments Incorporated
LM3648
www.ti.com.cn
ZHCSD27 –OCTOBER 2014
Typical Characteristics (continued)
Ambient temperature is 25°C, input voltage is 3.6 V, HWEN = VIN, CIN = COUT = 2 × 10 µF and L = 1 µH, unless otherwise
noted.
0.4
0.39
0.38
0.37
0.36
0.35
0.34
0.33
0.32
1.07
1.06
1.05
1.04
1.03
1.02
1.01
1
TA = -40qC
TA = -+25qC
TA = +85qC
TA = -40qC
TA = +25qC
TA = +85qC
0.99
0.98
0.97
0.96
0.95
0.94
0.93
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
VIN (V)
D025
D023
ƒSW = 2 MHz
Brightness Code = 0x7F
Torch
ƒSW = 2 MHz
Brightness Code = 0x2B
Flash
Figure 7. LED Current vs Input Voltage
Figure 6. LED Current vs Input Voltage
0.4
0.39
0.38
0.37
0.36
0.35
0.34
0.33
0.32
1.2
1
TA = -40qC
TA = -+25qC
TA = +85qC
TA = -40qC
TA = +25qC
TA = +85qC
0.8
0.6
0.4
0.2
0
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
VIN (V)
D026
D007
ƒSW = 4 MHz
Brightness Code = 0x7F
Torch
HWEN = 0 V
I2C = 0 V
Figure 8. LED Current vs Input Voltage
Figure 9. Shutdown Current vs Input Voltage
3
2.5
2
7
6
5
4
3
2
1
0
TA = -40qC
TA = +25qC
TA = +85qC
TA = -40qC
TA = +25qC
TA = +85qC
1.5
1
0.5
0
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
VIN (V)
D009
D008
HWEN = VIN
I2C = VIN
HWEN = 1.8 V
I2C = 0 V
Figure 10. Standby Current vs Input Voltage
Figure 11. Standby Current vs Input Voltage
Copyright © 2014, Texas Instruments Incorporated
7
LM3648
ZHCSD27 –OCTOBER 2014
www.ti.com.cn
Typical Characteristics (continued)
Ambient temperature is 25°C, input voltage is 3.6 V, HWEN = VIN, CIN = COUT = 2 × 10 µF and L = 1 µH, unless otherwise
noted.
2.2
2.16
2.12
2.08
2.04
2
1.96
1.92
1.88
1.84
1.8
1.76
1.72
1.68
1.64
1.6
7
6
5
4
3
2
1
0
TA = -40qC
TA = +25qC
TA = +85qC
TA = -40qC
TA = +25qC
TA = +85qC
2.5
3
3.5
4
4.5
5
5.5
2.5
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
VIN (V)
VIN (V)
D010
D011
HWEN = 1.8 V
I2C = 1.8 V
ƒSW = 2 MHz
Brightness Code = 0x3F
Flash
VLED = 4.5 V
ICL = 1.9 A
Figure 12. Standby Current vs Input Voltage
Figure 13. Inductor Current Limit vs Input Voltage
2.2
2.16
2.12
2.08
2.04
2
1.96
1.92
1.88
1.84
1.8
3
2.8
2.6
2.4
2.2
2
1.76
1.72
1.68
1.64
1.6
1.8
1.6
1.4
TA = -40qC
TA = +25qC
TA = +85qC
TA = -40qC
TA = +25qC
TA = +85qC
2.5
2.7
2.9
3.1
3.3
VIN (V)
3.5
3.7
3.9
4.1
4.3
2.5 2.75
3
3.25 3.5 3.75
VIN (V)
4
4.25 4.5 4.75
5
D012
D013
ƒSW = 4 MHz
Brightness Code = 0x3F
Flash
VLED = 4.5 V
ICL = 1.9 A
ƒSW = 2 MHz
Brightness Code = 0x3F
Flash
VLED = 4.5 V
ICL = 2.8 A
Figure 14. Inductor Current Limit vs Input Voltage
Figure 15. Inductor Current Limit vs Input Voltage
3
2.8
2.6
2.4
2.2
2
2.125
2.1
TA = +25qC
TA = +85qC
TA = -40qC
2.075
2.05
2.025
2
1.975
1.95
1.925
1.9
1.8
1.6
1.4
TA = -40qC
TA = +25qC
TA = +85qC
1.875
2.5 2.75
3
3.25 3.5 3.75
VIN (V)
4
4.25 4.5 4.75
5
2.5 2.75
3
3.25 3.5 3.75
VIN (V)
4
4.25 4.5 4.75
5
D014
D017
ƒSW = 4 MHz
Brightness Code = 0x3F
Flash
VLED = 4.5 V
ICL = 2.8 A
Figure 16. Inductor Current Limit vs Input Voltage
Figure 17. 2-MHz Switching Frequency vs Input Voltage
8
Copyright © 2014, Texas Instruments Incorporated
LM3648
www.ti.com.cn
ZHCSD27 –OCTOBER 2014
Typical Characteristics (continued)
Ambient temperature is 25°C, input voltage is 3.6 V, HWEN = VIN, CIN = COUT = 2 × 10 µF and L = 1 µH, unless otherwise
noted.
4.25
TA = +25qC
4.2
TA = +85qC
TA = -40qC
4.15
4.1
4.05
4
3.95
3.9
3.85
3.8
3.75
2.5 2.75
3
3.25 3.5 3.75
VIN (V)
4
4.25 4.5 4.75
5
D0178
Figure 18. 4-MHz Switching Frequency vs Input Voltage
Copyright © 2014, Texas Instruments Incorporated
9
LM3648
ZHCSD27 –OCTOBER 2014
www.ti.com.cn
7 Detailed Description
7.1 Overview
The LM3648 is a high-power white LED flash driver capable of delivering up to 1.5 A to the LED. The device
incorporates a 2-MHz or 4-MHz constant frequency-synchronous current-mode PWM boost converter and a high-
side current source to regulate the LED current over the 2.5-V to 5.5-V input voltage range.
The LM3648 PWM DC/DC boost converter switches and boosts the output to maintain at least VHR across the
current source. This minimum headroom voltage ensures that the current source remains in regulation. If the
input voltage is above the LED voltage + current source headroom voltage the device does not switch, but turns
the PFET on continuously (Pass mode). In Pass mode the difference between (VIN − ILED x RPMOS) and the
voltage across the LED is dropped across the current source.
The LM3648 has three logic inputs including a hardware Flash Enable (STROBE), a hardware Torch Enable
(TORCH/TEMP, TORCH = default), and a Flash Interrupt input (TX) designed to interrupt the flash pulse during
high battery-current conditions. These logic inputs have internal 300-kΩ (typ.) pulldown resistors to GND.
Additional features of the LM3648 include an internal comparator for LED thermal sensing via an external NTC
thermistor and an input voltage monitor that can reduce the Flash current during low VIN conditions. It also has a
Hardware Enable (HWEN) pin that can be used to reset the state of the device and the registers by pulling the
HWEN pin to ground.
Control is done via an I2C-compatible interface. This includes adjustment of the Flash and Torch current levels,
changing the Flash Timeout Duration, and changing the switch current limit. Additionally, there are flag and
status bits that indicate flash current time-out, LED overtemperature condition, LED failure (open/short), device
thermal shutdown, TX interrupt, and VIN undervoltage conditions.
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7.2 Functional Block Diagram
SW
Over Voltage
Comparator
IN
2/4 MHz
Oscillator
-
+
V
REF
V
OVP
86 m:
Input Voltage
Flash Monitor
OUT
UVLO
I
LED
PWM
Control
65 m:
TORCH/
TEMP
I
NTC
Thermal
Shutdown
+150oC
LED
Error
Amplifier
+
-
OUT-VHR
Current Sense/
Current Limit
NTC V
TRIP
Slope
Compensation
Soft-Start
SDA
Control
Logic/
Registers
2
I C
Interface
SCL
ENABLE
GND
TX
STROBE
7.3 Feature Description
7.3.1 Flash Mode
In Flash Mode, the LED current source (LED) provides 64 target current levels from 21.8 mA to 1500 mA. Once
the Flash sequence is activated the current source (LED) ramps up to the programmed Flash current by stepping
through all current steps until the programmed current is reached. The headroom in the current source can be
regulated to provide 21.8 mA to 1.5 A.
When the device is enabled in Flash Mode through the Enable Register, all mode bits in the Enable Register are
cleared after a flash time-out event.
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Feature Description (continued)
7.3.2 Torch Mode
In Torch mode, the LED current source (LED) provide 128 target current levels from 1.954 mA to 358 mA. The
Torch current is adjusted via the LED Torch Brightness Register. Torch mode is activated by the Enable Register
(setting M1, M0 to '10'), or by pulling the TORCH/TEMP pin HIGH when the pin is enabled (Enable Register) and
set to Torch Mode. Once the TORCH sequence is activated the active current source (LED) ramps up to the
programmed Torch current by stepping through all current steps until the programmed current is reached. The
rate at which the current ramps is determined by the value chosen in the Timing Register.
Torch Mode is not affected by Flash Timeout or by a TX Interrupt event.
7.3.3 IR Mode
In IR Mode, the target LED current is equal to the value stored in the LED Flash Brightness Registers. When IR
mode is enabled (setting M1, M0 to '01'), the boost converter turns on and sets the output equal to the input
(pass-mode). At this point, toggling the STROBE pin enables and disables the LED current source (if enabled).
The STROBE pin can only be set to be Level sensitive, meaning all timing of the IR pulse is externally controlled.
In IR Mode, the current source does not ramp the LED output to the target. The current transitions immediately
from off to on and then on to off.
BOOST
PASS
OFF
VOUT
STROBE
ILED
Figure 19. IR Mode with Boost
VOUT
STROBE
ILED
Figure 20. IR Mode Pass Only
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Feature Description (continued)
VOUT
STROBE
ILED
Figure 21. IR Mode Timeout
7.4 Device Functioning Modes
7.4.1 Start-Up (Enabling The Device)
Turnon of the LM3648 Torch and Flash modes can be done through the Enable Register. On start-up, when
VOUT is less than VIN the internal synchronous PFET turns on as a current source and delivers 200 mA (typ.) to
the output capacitor. During this time the current source (LED) is off. When the voltage across the output
capacitor reaches 2.2 V (typ.), the current source turns on. At turnon the current source steps through each
FLASH or TORCH level until the target LED current is reached. This gives the device a controlled turnon and
limits inrush current from the VIN supply.
7.4.2 Pass Mode
The LM3648 starts up in Pass Mode and stays there until Boost Mode is needed to maintain regulation. If the
voltage difference between VOUT and VLED falls below VHR, the device switches to Boost Mode. In Pass Mode the
boost converter does not switch, and the synchronous PFET turns fully on bringing VOUT up to VIN − ILED
x
RPMOS. In Pass Mode the inductor current is not limited by the peak current limit.
7.4.3 Power Amplifier Synchronization (TX)
The TX pin is a Power Amplifier Synchronization input. This is designed to reduce the flash LED current and thus
limit the battery current during high battery current conditions such as PA transmit events. When the LM3648 is
engaged in a Flash event, and the TX pin is pulled high, the LED current is forced into Torch Mode at the
programmed Torch current setting. If the TX pin is then pulled low before the Flash pulse terminates, the LED
current returns to the previous Flash current level. At the end of the Flash time-out, whether the TX pin is high or
low, the LED current turns off.
7.4.4 Input Voltage Flash Monitor (IVFM)
The LM3648 has the ability to adjust the flash current based upon the voltage level present at the IN pin utilizing
the Input Voltage Flash Monitor (IVFM). The adjustable threshold IVFM-D ranges from 2.9 V to 3.6 V in 100-mV
steps, with three different usage modes (Stop and Hold, Adjust Down Only, Adjust Up and Down). The Flags2
Register has the IVFM flag bit set when the input voltage crosses the IVFM-D value. Additionally, the IVFM-D
threshold sets the input voltage boundary that forces the LM3648 to either stop ramping the flash current during
start-up (Stop and Hold Mode) or to start decreasing the LED current during the flash (Down Adjust Only and Up
and Down Adjust). In Adjust Up and Down mode, the IVFM-D value plus the hysteresis voltage threshold set the
input voltage boundary that forces the LM3648 to start ramping the flash current back up towards the target.
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Device Functioning Modes (continued)
IVFM ENABLE
LEVEL STROBE
VIN PROFILE for Stop and Hold Mode
IVFM-D
Set Target Flash Current
Dotted line shows O/P Current
Profile with IVFM Disabled
O/P Current
Profile in Stop
and Hold Mode
SET RAMP FROM
THE RAMP
REGISTER USED
VIN PROFILE for Down Mode
Hysteresis
IVFM-D
O/P Current Profile
in Down Mode
VIN PROFILE for Up/ Down Mode
Hysteresis
IVFM-D
O/P Current Profile
in Up and Down
Mode
Figure 22. IVFM Modes
14
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Device Functioning Modes (continued)
7.4.5 Fault/Protections
7.4.5.1 Fault Operation
If the LM3648 enters a fault condition, the device sets the appropriate flag in the Flags1 and Flags2 Registers
(0x0A and 0x0B), and places the device into standby by clearing the Mode Bits ([1],[0]) in the Enable Register.
The LM3648 remains in standby until an I2C read of the Flags1 and Flags2 Registers are completed. Upon
clearing the flags/faults, the device can be restarted (Flash, Torch, IR, etc.). If the fault is still present, the
LM3648 re-enters the fault state and enters standby again.
7.4.5.2 Flash Time-Out
The Flash Time-Out period sets the amount of time that the Flash Current is being sourced from the current
source (LED). The LM3648 has 16 timeout levels ranging from 10 ms to 400 ms (see Timing Configuration
Register (0x08) for more detail).
7.4.5.3 Overvoltage Protection (OVP)
The output voltage is limited to typically 5 V (see VOVP spec in the Electrical Characteristics). In situations such
as an open LED, the LM3648 raises the output voltage in order to keep the LED current at its target value. When
VOUT reaches 5 V (typ.), the overvoltage comparator trips and turns off the internal NFET. When VOUT falls below
the “VOVP Off Threshold”, the LM3648 begins switching again. The mode bits are cleared, and the OVP flag is
set, when an OVP condition is present for three rising OVP edges. This prevents momentary OVP events from
forcing the device to shut down.
7.4.5.4 Current Limit
The LM3648 features two selectable inductor current limits that are programmable through the I2C-compatible
interface. When the inductor current limit is reached, the LM3648 terminates the charging phase of the switching
cycle. Switching resumes at the start of the next switching period. If the overcurrent condition persists, the device
operates continuously in current limit.
Since the current limit is sensed in the NMOS switch, there is no mechanism to limit the current when the device
operates in Pass Mode (current does not flow through the NMOS in pass mode). In Boost mode or Pass mode if
VOUT falls below 2.3 V, the device stops switching, and the PFET operates as a current source limiting the
current to 200 mA. This prevents damage to the LM3648 and excessive current draw from the battery during
output short-circuit conditions. The mode bits are not cleared upon a Current Limit event, but a flag is set.
7.4.5.5 NTC Thermistor Input (Torch/Temp)
The TORCH/TEMP pin, when set to TEMP mode, serves as a threshold detector and bias source for negative
temperature coefficient (NTC) thermistors. When the voltage at TEMP goes below the programmed threshold,
the LM3648 is placed into standby mode. The NTC threshold voltage is adjustable from 200 mV to 900 mV in
100-mV steps. The NTC bias current is set to 50 µA. The NTC detection circuitry can be enabled or disabled via
the Enable Register. If enabled, the NTC block turns on and off during the start and stop of a Flash/Torch event.
Additionally, the NTC input looks for an open NTC connection and a shorted NTC connection. If the NTC input
falls below 100 mV, the NTC short flag is set, and the device is disabled. If the NTC input rises above 2.3 V, the
NTC Open flag is set, and the device is disabled. These fault detections can be individually disabled/enabled via
the NTC Open Fault Enable bit and the NTC Short Fault Enable bit.
V
IN
NTC Control Block
I
NTC
TEMP
-
+
Control
Logic
V
TRIP
NTC
Figure 23. Temp Detection Diagram
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Device Functioning Modes (continued)
7.4.5.6 Undervoltage Lockout (UVLO)
The LM3648 has an internal comparator that monitors the voltage at IN and forces the LM3648 into standby if
the input voltage drops to 2.5 V. If the UVLO monitor threshold is tripped, the UVLO flag bit is set in the Flags1
Register (0x0A). If the input voltage rises above 2.5 V, the LM3648 is not available for operation until there is an
I2C read of the Flags1 Register (0x0A). Upon a read, the Flags1 register is cleared, and normal operation can
resume if the input voltage is greater than 2.5 V.
7.4.5.7 Thermal Shutdown (TSD)
When the LM3648 die temperature reaches 150°C, the thermal shutdown detection circuit trips, forcing the
LM3648 into standby and writing a '1' to the corresponding bit of the Flags1 Register (0x0A) (Thermal Shutdown
bit). The LM3648 is only allowed to restart after the Flags1 Register (0x0A) is read, clearing the fault flag. Upon
restart, if the die temperature is still above 150°C, the LM3648 resets the Fault flag and re-enters standby.
7.4.5.8 LED and/or VOUT Short Fault
The LED Fault flags read back a '1' if the device is active in Flash or Torch mode and the LED output
experiences a short condition. The Output Short Fault flag reads back a '1' if the device is active in Flash or
Torch mode and the boost output experiences a short condition. An LED short condition is determined if the
voltage at LED goes below 500 mV (typ.) while the device is in Torch or Flash mode. There is a deglitch time of
256 μs before the LED Short flag is valid, and a deglitch time of 2.048 ms before the VOUT Short flag is valid.
The LED Short Faults can be reset to '0' by removing power to the LM3648, setting HWEN to '0', setting the SW
RESET bit to a '1', or by reading back the Flags1 Register (0x0A on LM3648). The mode bits are cleared upon
an LED and/or VOUT short fault.
7.5 Programming
7.5.1 Control Truth Table
MODE1
MODE0
STROBE EN
TORCH EN
STROBE PIN
TORCH PIN
ACTION
Standby
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
1
1
1
1
X
X
0
1
1
0
1
0
1
1
1
X
X
X
X
X
X
X
X
pos edge
Ext Torch
pos edge
X
Ext Flash
0
pos edge
Standalone Torch
Standalone Flash
Standalone Flash
Int Torch
pos edge
0
pos edge
pos edge
X
X
X
X
X
X
X
Int Flash
X
0
IRLED Standby
IRLED Standby
IRLED enabled
pos edge
7.5.2 I2C-Compatible Interface
7.5.2.1 Data Validity
The data on SDA must be stable during the HIGH period of the clock signal (SCL). In other words, the state of
the data line can only be changed when SCL is LOW.
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SCL
SDA
data
change
allowed
data
change
allowed
data
valid
data
change
allowed
data
valid
Figure 24. Data Validity Data
A pullup resistor between the controller's VIO line and SDA must be greater than [(VIO-VOL) / 3mA] to meet the
VOL requirement on SDA. Using a larger pullup resistor results in lower switching current with slower edges, while
using a smaller pullup results in higher switching currents with faster edges.
7.5.2.2 Start and Stop Conditions
START and STOP conditions classify the beginning and the end of the I2C session. A START condition is
defined as the SDA signal transitioning from HIGH to LOW while SCL line is HIGH. A STOP condition is defined
as the SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C master always generates START and
STOP conditions. The I2C bus is considered busy after a START condition and free after a STOP condition.
During data transmission, the I2C master can generate repeated START conditions. First START and repeated
START conditions are equivalent, function-wise.
SDA
SCL
S
P
Start Condition
Stop Condition
Figure 25. Start and Stop Conditions
7.5.2.3 Transferring Data
Every byte put on the SDA line must be eight bits long, with the most significant bit (MSB) transferred first. Each
byte of data has to be followed by an acknowledge bit. The acknowledge related clock pulse is generated by the
master. The master releases the SDA line (HIGH) during the acknowledge clock pulse. The LM3648 pulls down
the SDA line during the 9th clock pulse, signifying an acknowledge. The LM3648 generates an acknowledge
after each byte is received. There is no acknowledge created after data is read from the device.
After the START condition, the I2C master sends a chip address. This address is seven bits long followed by an
eighth bit which is a data direction bit (R/W). The LM3648 7-bit address is 0x63. For the eighth bit, a '0' indicates
a WRITE and a '1' indicates a READ. The second byte selects the register to which the data is written. The third
byte contains data to write to the selected register.
ack from slave
ack from slave
ack from slave
start msb Chip Address lsb
w
ack
msb Register Add lsb
ack
msb DATA lsb ack stop
SCL
SDA
start
Id = 63h
w
ack
addr = 0Ah
ack
Data = 03h
ack stop
Figure 26. Write Cycle W = Write (SDA = "0") R = Read (SDA = "1") Ack = Acknowledge
(SDA Pulled Down by Either Master or Slave) ID = Chip Address, 63h for LM3648
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7.5.2.4 I2C-Compatible Chip Address
The device address for the LM3648 is 1100011 (0x63). After the START condition, the I2C-compatible master
sends the 7-bit address followed by an eighth read or write bit (R/W). R/W = 0 indicates a WRITE and R/W = 1
indicates a READ. The second byte following the device address selects the register address to which the data is
written. The third byte contains the data for the selected register.
MSB
LSB
1
Bit 7
1
Bit 6
0
Bit 5
0
Bit 4
0
Bit 3
1
Bit 2
1
Bit 1
R/W
Bit 0
2
I C Slave Address (chip address)
Figure 27. I2C-Compatible Chip Address
7.6 Register Descriptions
POWER ON/RESET VALUE
REGISTER NAME
INTERNAL HEX ADDRESS
LM3648
0x80
0x01
0xBF
0xBF
0x09
0x1A
0x08
0x00
0x00
0x00
0x00
Enable Register
0x01
0x02
0x03
0x05
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
IVFM Register
LED Flash Brightness Register
LED Torch Brightness Register
Boost Configuration Register
Timing Configuration Register
TEMP Register
Flags1 Register
Flags2 Register
Device ID Register
Last Flash Register
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7.6.1 Enable Register (0x01)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TX Pin Enable Strobe Type
Strobe Enable TORCH/TEMP
Mode Bits: M1, M0
'00' = Standby (Default)
'01' = IR Drive
'10' = Torch
'11' = Flash
LED Enable
00 = OFF (Default )
11 = ON
0 = Disabled
1 = Enabled
(Default )
0 = Level
Triggered
(Default)
1 = Edge
Triggered
0 = Disabled
(Default )
1 = Enabled
Pin Enable
0 = Disabled
(Default )
01 and 10 are not valid settings
1 = Enabled
NOTE
Edge Strobe Mode is not valid in IR MODE. Switching between Level and Edge Strobe
Types while the device is enabled is not recommended.
In Edge or Level Strobe Mode, it is recommended that the trigger pulse width be set
greater than 1 ms to ensure proper turn-on of the device.
7.6.2 IVFM Register (0x02)
Bit 7
Bit 6
UVLO
Circuitry
(Default)
0 = Disabled
(Default)
Bit 5
Bit 4
Bit 3
Bit 2
IVFM
Hysteresis
0 = 0 mV
(Default)
Bit 1
Bit 0
IVFM Levels
000 = 2.9 V (Default)
001 = 3 V
010 = 3.1 V
011 = 3.2 V
100 = 3.3 V
101 = 3.4 V
110 = 3.5 V
111 = 3.6 V
IVFM Selection
00 = Disabled
01 = Stop and Hold Mode (Default)
10 = Down Mode
11 = Up and Down Mode
RFU
1 = 50 mV
1 = Enabled
NOTE
IVFM Mode Bits are static once the LM3648 is enabled in Torch, Flash or IR modes. If the
IVFM mode needs to be updated, disable the device and then change the mode bits to the
desired state.
7.6.3 LED Flash Brightness Register (0x03)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
MUST BE SET TO '10' FOR
PROPER OPERATION
LED Flash Brightness Level
IFLASH (mA) ≈ (Brightness Code × 23.45 mA) + 21.8 mA
000000 = 21.8 mA
.......................
011111 = 748.75 mA (Default)
.......................
111111 = 1.5 A
7.6.4 LED Torch Brightness Register (0x05)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
MUST BE SET LED Torch Brightness Levels
TO '1' FOR
PROPER
ITORCH (mA) ≈ (Brightness Code × 2.8 mA) + 1.954 mA
0000000 = 1.954 mA
OPERATION
.......................
0111111 = 178.35 mA (Default)
.......................
1111111 = 357.6mA
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7.6.5 Boost Configuration Register (0x07)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Boost
Frequency
Select
Bit 0
LED Pin Short
Fault Detect
0 = Disabled
1 = Enabled
(Default)
Boost Mode
0 = Normal
(Default)
Boost Current
Limit Setting
0 = 1.9 A
1 = 2.8 A
(Default)
Software
Reset Bit
0 = Not Reset
(Default)
RFU
RFU
RFU
1 = Pass Mode 0 = 2 MHz
Only
(Default)
1 = 4 MHz
1 = Reset
7.6.6 Timing Configuration Register (0x08)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Torch Current Ramp Time
000 = No Ramp
001 = 1 ms (Default)
010 = 32 ms
Flash Time-Out Duration
0000 = 10 ms
0001 = 20 ms
0010 = 30 ms
011 = 64 ms
0011 = 40 ms
100 = 128 ms
0100 = 50 ms
101 = 256 ms
0101 = 60 ms
110 = 512 ms
0110 = 70 ms
RFU
111 = 1024 ms
0111 = 80 ms
1000 = 90 ms
1001 = 100 ms
1010 = 150 ms (Default)
1011 = 200 ms
1100 = 250 ms
1101 = 300 ms
1110 = 350 ms
1111 = 400 ms
7.6.7 TEMP Register (0x09)
Bit 7
Bit 6
TORCH
Polarity
0 = Active
High (Default) (Default)
(Pulldown
Resistor
Enabled)
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NTC Open
Fault Enable
0 = Disabled
NTC Short
Fault Enable
0 = Disabled
(Default)
TEMP Detect Voltage Threshold
000 = 0.2 V
001 = 0.3 V
010 = 0.4 V
011 = 0.5 V
TORCH/TEMP
Function
Select
0 = TORCH
(Default)
1 =Enable
1 =Enable
RFU
100 = 0.6 V (Default)
101 = 0.7 V
1 = TEMP
1 = Active Low
(Pulldown
Resistor
110 = 0.8 V
111 = 0.9 V
Disabled)
NOTE
The Torch Polarity bit is static once the LM3648 is enabled in Torch, Flash, or IR modes.
If the Torch Polarity bit needs to be updated, disable the device and then change the
Torch Polarity bit to the desired state.
7.6.8 Flags1 Register (0x0A)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Thermal
Shutdown
(TSD) Fault
VOUT Short
Fault
VLED Short
Fault
VLED Short
Fault
Current Limit
Flag
Flash Time-Out
Flag
TX Flag
UVLO Fault
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7.6.9 Flags2 Register (0x0B)
Bit 7
RFU
Bit 6
RFU
Bit 5
RFU
Bit 4
Bit 3
Bit 2
Bit 1
OVP Fault
Bit 0
NTC Short
Fault
IVFM Trip
Flag
TEMP Trip
Fault
NTC Open Fault
7.6.10 Device ID Register (0x0C)
Bit 7
RFU
Bit 6
RFU
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Device ID
Silicon Revision Bit
'011'
'010'
7.6.11 Last Flash Register (0x0D)
Bit 7
RFU
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
The value stored is always the last current value the IVFM detection block set. ILED = IFLASH-TARGET × ((Code + 1) / 128)
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8 Applications and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LM3648 can drive a flash LED at currents up to 1.5 A. The 2-MHz/4-MHz DC/DC boost regulator allows for
the use of small value discrete external components.
8.2 Typical Application
L1
1 PH
LM3648
IN
SW
VIN
2.5V t 5.5V
C1
10 PF
HWEN
SDA
OUT
C2
10 PF
SCL
LED
PP/PC
STROBE
TORCH/
TEMP
TX
GND
Figure 28. LM3648 Typical Application
8.2.1 Design Requirements
Example requirements based on default register values:
DESIGN PARAMETER
Input Voltage Range
Brightness Control
EXAMPLE VALUE
2.5 V to 5.5 V
I2C Register
LED Configuration
1 Flash LED
Boost Switching Frequency
Flash Brightness
2 MHz (4 MHz selectable)
1.5-A Max Current
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8.2.2 Detailed Design Procedure
8.2.2.1 Output Capacitor Selection
The LM3648 is designed to operate with a 10-µF ceramic output capacitor. When the boost converter is running,
the output capacitor supplies the load current during the boost converter on-time. When the NMOS switch turns
off, the inductor energy is discharged through the internal PMOS switch, supplying power to the load and
restoring charge to the output capacitor. This causes a sag in the output voltage during the on-time and a rise in
the output voltage during the off-time. The output capacitor is therefore chosen to limit the output ripple to an
acceptable level depending on load current and input/output voltage differentials and also to ensure the converter
remains stable.
Larger capacitors such as a 22-µF or capacitors in parallel can be used if lower output voltage ripple is desired.
To estimate the output voltage ripple considering the ripple due to capacitor discharge (ΔVQ) and the ripple due
to the capacitors ESR (ΔVESR) use the following equations:
For continuous conduction mode, the output voltage ripple due to the capacitor discharge is:
(
)
ILED x VOUT - V
IN
'VQ =
fSW x VOUT x COUT
(1)
The output voltage ripple due to the output capacitors ESR is found by:
ILED x VOUT
§
©
·
¹
+'IL
'VESR = RESR
x
VIN
where
(
)
x VOUT - V
IN
V
IN
'IL =
2x fSW x L x VOUT
(2)
In ceramic capacitors the ESR is very low so the assumption is that 80% of the output voltage ripple is due to
capacitor discharge and 20% from ESR. Table 1 lists different manufacturers for various output capacitors and
their case sizes suitable for use with the LM3648.
8.2.2.2 Input Capacitor Selection
Choosing the correct size and type of input capacitor helps minimize the voltage ripple caused by the switching
of the LM3648 boost converter and reduce noise on the boost converter's input pin that can feed through and
disrupt internal analog signals. In the typical application circuit a 10-µF ceramic input capacitor works well. It is
important to place the input capacitor as close as possible to the LM3648 input (IN) pin. This reduces the series
resistance and inductance that can inject noise into the device due to the input switching currents. Table 1 lists
various input capacitors recommended for use with the LM3648.
Table 1. Recommended Input/Output Capacitors (X5R/X7R Dielectric)
MANUFACTURER
TDK Corporation
TDK Corporation
Murata
PART NUMBER
C1608JB0J106M
VALUE
10 µF
10 µF
10 µF
10 µF
CASE SIZE
VOLTAGE RATING
0603 (1.6 mm × 0.8 mm × 0.8 mm)
0805 (2.0 mm × 1.25 mm × 1.25 mm)
0603 (1.6 mm x 0.8 mm x 0.8 mm)
0805 (2.0 mm × 1.25 mm × 1.25 mm)
6.3 V
10 V
6.3 V
10 V
C2012JB1A106M
GRM188R60J106M
GRM21BR61A106KE19
Murata
8.2.2.3 Inductor Selection
The LM3648 is designed to use a 0.47-µH or 1-µH inductor. Table 2 lists various inductors and their
manufacturers that work well with the LM3648. When the device is boosting (VOUT > VIN) the inductor is typically
the largest area of efficiency loss in the circuit. Therefore, choosing an inductor with the lowest possible series
resistance is important. Additionally, the saturation rating of the inductor should be greater than the maximum
operating peak current of the LM3648. This prevents excess efficiency loss that can occur with inductors that
operate in saturation. For proper inductor operation and circuit performance, ensure that the inductor saturation
and the peak current limit setting of the LM3648 are greater than IPEAK in the following calculation:
Copyright © 2014, Texas Instruments Incorporated
23
LM3648
ZHCSD27 –OCTOBER 2014
www.ti.com.cn
( )
IN x VOUT - V
IN
ILOAD VOUT
V
IPEAK
=
x
+'IL
where
'IL =
K
V
2 x fSW x L x VOUT
IN
where
•
ƒSW = 2 or 4 MHz
(3)
Efficiency details can be found in the Application Curves .
Table 2. Recommended Inductors
MANUFACTURER
TOKO
L
PART NUMBER
DFE201610P-R470M
DFE201610P-1R0M
DIMENSIONS (L×W×H)
2.0 mm x 1.6 mm x 1.0 mm
2.0 mm x 1.6 mm x 1.0 mm
ISAT
4.1 A
3.7 A
RDC
0.47 µH
1 µH
32 mΩ
58 mΩ
TOKO
8.2.3 Application Curves
Ambient temperature is 25°C, input voltage is 3.6 V, HWEN = VIN, CIN = 2 × 10 µF, COUT = 2 × 10 µF and L = 1 µH, unless
otherwise noted.
100
95
90
85
80
75
70
65
60
55
50
100
95
90
85
80
75
70
65
60
55
50
VLED = 3.0V
VLED = 3.2V
VLED = 3.5V
VLED = 3.8V
VLED = 4.1V
VLED = 4.4V
VLED = 3.0V
VLED = 3.2V
VLED = 3.5V
VLED = 3.8V
VLED = 4.1V
VLED = 4.4V
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
VIN (V)
D019
D020
ƒSW = 2 MHz
Brightness Code = 0x3F
Flash
ƒSW = 4 MHz
Brightness Code = 0x3F
Flash
Figure 29. 2-MHz LED Efficiency vs Input Voltage
Figure 30. 4-MHz LED Efficiency vs Input Voltage
100
96
92
88
84
80
76
72
68
64
60
100
96
92
88
84
80
76
72
68
64
60
TA = -40qC
TA = +25qC
TA = +85qC
TA = -40qC
TA = +25qC
TA = +85qC
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
VIN (V)
D028
D029
ƒSW = 2 MHz
Brightness Code = 0x3F
Flash
VLED = 3.55 V
ƒSW = 4 MHz
Brightness Code = 0x3F
Flash
VLED = 3.55 V
Figure 31. LED Efficiency vs Input Voltage
Figure 32. LED Efficiency vs Input Voltage
24
Copyright © 2014, Texas Instruments Incorporated
LM3648
www.ti.com.cn
ZHCSD27 –OCTOBER 2014
Ambient temperature is 25°C, input voltage is 3.6 V, HWEN = VIN, CIN = 2 × 10 µF, COUT = 2 × 10 µF and L = 1 µH, unless
otherwise noted.
100
96
92
88
84
80
76
72
68
64
60
100
95
90
85
80
75
70
65
60
55
50
TA = -40qC
TA = +25qC
TA = +85qC
TA = -40qC
TA = +25qC
TA = +85qC
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
VIN (V)
D030
D033
ƒSW = 2 MHz
Brightness Code = 0x2B
Flash
VLED = 3.32 V
ƒSW = 2 MHz
Brightness Code = 0x3F
Torch
VLED = 2.83 V
Figure 33. LED Efficiency vs Input Voltage
Figure 34. LED Efficiency vs Input Voltage
100
95
90
85
80
75
70
65
60
55
50
100
95
90
85
80
75
70
65
60
55
50
TA = -40qC
TA = +25qC
TA = +85qC
TA = -40qC
TA = +25qC
TA = +85qC
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
VIN (V)
D034
D035
ƒSW = 4 MHz
Brightness Code = 0x3F
Torch
VLED = 2.83 V
ƒSW = 2 MHz
Brightness Code = 0x7F
Torch
VLED = 2.83 V
Figure 35. LED Efficiency vs Input Voltage
Figure 36. LED Efficiency vs Input Voltage
100
95
90
85
80
75
70
65
60
55
50
TA = -40qC
TA = +25qC
TA = +85qC
VOUT (2 V/DIV)
ILED (500 mA/DIV)
IIN (500 mA/DIV)
Time (400 Ps / DIV)
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
D036
ƒSW = 4 MHz
Brightness Code = 0x7F
Torch
VLED = 2.83 V
ƒSW = 2 MHz
VLED = 3.18 V
Brightness Code = 0x7F
Figure 37. LED Efficiency vs Input Voltage
Figure 38. Start-Up
Copyright © 2014, Texas Instruments Incorporated
25
LM3648
ZHCSD27 –OCTOBER 2014
www.ti.com.cn
Ambient temperature is 25°C, input voltage is 3.6 V, HWEN = VIN, CIN = 2 × 10 µF, COUT = 2 × 10 µF and L = 1 µH, unless
otherwise noted.
Tx Signal
VOUT (2 V/DIV)
VOUT (2 V/DIV)
ILED (500 mA/DIV)
ILED (500 mA/DIV)
IIN (500 mA/DIV)
IIN (1 A/DIV)
Time (400 Ps / DIV)
Time (2 ms / DIV)
ƒSW = 2 MHz
VLED = 3.18 V
ƒSW = 2 MHz
VLED = 3.18 V
Brightness Code = 0x7F
Brightness Code = 0x7F
Figure 39. Ramp Down
Figure 40. TX Interrupt
VOUT (50 mV/DIV)
VOUT (50 mV/DIV)
ILED (20 mA/DIV)
IL (100 mA/DIV)
ILED (20 mA/DIV)
IL (100 mA/DIV)
Time (400 ns / DIV)
Time (400 ns / DIV)
ƒSW = 2 MHz
VLED = 3.18 V
ƒSW = 4 MHz
VLED = 3.18 V
Brightness Code = 0x7F
Brightness Code = 0x7F
Figure 41. Ripple @ 2 MHz
Figure 42. Ripple @ 4 MHz
26
Copyright © 2014, Texas Instruments Incorporated
LM3648
www.ti.com.cn
ZHCSD27 –OCTOBER 2014
9 Power Supply Recommendations
The LM3648 is designed to operate from an input voltage supply range between 2.5 V and 5.5 V. This input
supply must be well regulated and capable to supply the required input current. If the input supply is located far
from the LM3648 additional bulk capacitance may be required in addition to the ceramic bypass capacitors.
10 Layout
10.1 Layout Guidelines
The high switching frequency and large switching currents of the LM3648 make the choice of layout important.
The following steps should be used as a reference to ensure the device is stable and maintains proper LED
current regulation across its intended operating voltage and current range.
1. Place CIN on the top layer (same layer as the LM3648) and as close to the device as possible. The input
capacitor conducts the driver currents during the low-side MOSFET turnon and turnoff and can detect current
spikes over 1 A in amplitude. Connecting the input capacitor through short, wide traces to both the IN and
GND pins reduces the inductive voltage spikes that occur during switching which can corrupt the VIN line.
2. Place COUT on the top layer (same layer as the LM3648) and as close as possible to the OUT and GND pins.
The returns for both CIN and COUT should come together at one point, as close to the GND pin as possible.
Connecting COUT through short, wide traces reduce the series inductance on the OUT and GND pins that can
corrupt the VOUT and GND lines and cause excessive noise in the device and surrounding circuitry.
3. Connect the inductor on the top layer close to the SW pin. There should be a low-impedance connection
from the inductor to SW due to the large DC inductor current, and at the same time the area occupied by the
SW node should be small so as to reduce the capacitive coupling of the high dV/dT present at SW that can
couple into nearby traces.
4. Avoid routing logic traces near the SW node so as to avoid any capacitively coupled voltages from SW onto
any high-impedance logic lines such as TORCH/TEMP, STROBE, HWEN, SDA, and SCL. A good approach
is to insert an inner layer GND plane underneath the SW node and between any nearby routed traces. This
creates a shield from the electric field generated at SW.
5. Terminate the Flash LED cathode directly to the GND pin of the LM3648. If possible, route the LED return
with a dedicated path so as to keep the high amplitude LED current out of the GND plane. For a Flash LED
that is routed relatively far away from the LM3648, a good approach is to sandwich the forward and return
current paths over the top of each other on two layers. This helps reduce the inductance of the LED current
path.
版权 © 2014, Texas Instruments Incorporated
27
LM3648
ZHCSD27 –OCTOBER 2014
www.ti.com.cn
10.2 Layout Example
IN
10 PF
VIAs to GND
Plane
GND
IN
SDA
SCL
SDA
SCL
1 P+
10 PF
SW
STROBE
SW
TORCH/
TEMP
TORCH/
TEMP
HWEN
OUT
LED
OUT
LED
TX
TX
LED
LED
Figure 43. LM3648 Layout Example
28
版权 © 2014, Texas Instruments Incorporated
LM3648
www.ti.com.cn
ZHCSD27 –OCTOBER 2014
11 器件和文档支持
11.1 器件支持
11.1.1 第三方产品免责声明
TI 发布的与第三方产品或服务有关的信息，不能构成与此类产品或服务或保修的适用性有关的认可，不能构成此类
产品或服务单独或与任何 TI 产品或服务一起的表示或认可。
11.2 文档支持
11.2.1 相关文档ꢀ
相关文档如下：
德州仪器 (TI) 应用手册 1112：《DSBGA 晶圆级芯片规模封装》（文献编号：SNVA009）。
11.3 商标
All trademarks are the property of their respective owners.
11.4 静电放电警告
ESD 可能会损坏该集成电路。德州仪器 (TI) 建议通过适当的预防措施处理所有集成电路。如果不遵守正确的处理措施和安装程序 , 可
能会损坏集成电路。
ESD 的损坏小至导致微小的性能降级 , 大至整个器件故障。 精密的集成电路可能更容易受到损坏 , 这是因为非常细微的参数更改都可
能会导致器件与其发布的规格不相符。
11.5 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。
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。
版权 © 2014, Texas Instruments Incorporated
29
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)
LM3648TTYFFR
LM3648YFFR
ACTIVE
ACTIVE
DSBGA
DSBGA
YFF
YFF
12
12
3000 RoHS & Green
3000 RoHS & Green
SNAGCU
Level-1-260C-UNLIM
Level-1-260C-UNLIM
-40 to 85
-40 to 85
3648TT
3648
SNAGCU
(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
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
Addendum-Page 2
PACKAGE OUTLINE
YFF0012
DSBGA - 0.625 mm max height
SCALE 8.000
DIE SIZE BALL GRID ARRAY
A
B
E
BALL A1
CORNER
D
0.625 MAX
C
SEATING PLANE
0.05 C
BALL TYP
0.30
0.12
0.8 TYP
0.4 TYP
D
C
B
SYMM
1.2
TYP
D: Max = 1.69 mm, Min = 1.63 mm
E: Max = 1.31 mm, Min = 1.25 mm
A
0.4 TYP
1
2
3
0.3
12X
0.015
0.2
SYMM
C A
B
4222191/A 07/2015
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
www.ti.com
EXAMPLE BOARD LAYOUT
YFF0012
DSBGA - 0.625 mm max height
DIE SIZE BALL GRID ARRAY
(0.4) TYP
3
12X ( 0.23)
(0.4) TYP
1
2
A
B
C
SYMM
D
SYMM
LAND PATTERN EXAMPLE
SCALE:30X
0.05 MAX
0.05 MIN
METAL UNDER
SOLDER MASK
(
0.23)
METAL
(
0.23)
SOLDER MASK
OPENING
SOLDER MASK
OPENING
NON-SOLDER MASK
SOLDER MASK
DEFINED
DEFINED
(PREFERRED)
SOLDER MASK DETAILS
NOT TO SCALE
4222191/A 07/2015
NOTES: (continued)
3. Final dimensions may vary due to manufacturing tolerance considerations and also routing constraints. For more information,
see Texas Instruments literature number SNVA009 (www.ti.com/lit/snva009).
www.ti.com
EXAMPLE STENCIL DESIGN
YFF0012
DSBGA - 0.625 mm max height
DIE SIZE BALL GRID ARRAY
(0.4) TYP
(R0.05) TYP
12X ( 0.25)
1
2
3
A
(0.4) TYP
B
SYMM
METAL
TYP
C
D
SYMM
SOLDER PASTE EXAMPLE
BASED ON 0.1 mm THICK STENCIL
SCALE:30X
4222191/A 07/2015
NOTES: (continued)
4. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release.
www.ti.com
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这些资源可供使用 TI 产品进行设计的熟练开发人员使用。您将自行承担以下全部责任：(1) 针对您的应用选择合适的 TI 产品，(2) 设计、验
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邮寄地址：Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
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