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参数资料
| 型号： | MAX8645XETI+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 10/14页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WHITE BCKLGT 28-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 恒定电流： | 是 |
| 拓扑： | 线性（LDO），切换式电容器（充电泵） |
| 输出数： | 8 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 1MHz |
| 电源电压： | 2.7 V ~ 5.5 V |
| 输出电压： | 5.5V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 85°C |
1x/1.5x/2x White LED Charge Pumps with Two
LDOs in 4mm x 4mm TQFN
INITIAL t HI
0
≥ 200 μ s
1
2
3
4
5
27
28
29
30
31
32
ENM1 AND ENM2
29/32 28/32
OR
ENF
I M_ OR I F_
SHUTDOWN
t SOFT-START
32/32
31/32 30/32
t LO
500ns TO 250 μ s
27/32
t HI
≥ 500ns
5/32
4/32
3/32
2/32
1/32
32/32 31/32
t SHDN
2.5ms (typ)
SHUTDOWN
Figure 1. ENM_ and ENF Timing Diagram
Thermal Shutdown
The MAX8645X/MAX8645Y include a thermal-limit circuit
that shuts down the IC at approximately +160°C. Turn-
on occurs after the IC cools by approximately 20°C.
Applications Information
Setting the Main Output Current
SETM controls M1–M6 regulation current. Current flow-
ing into M1, M2, M3, M4, M5, and M6 is a multiple of
the current flowing out of SETM:
I M1 = I M2 = I M3 = I M4 = I M5 = I M6 = K x (0.6V / R SETM )
where K = 230, and R SETM is the resistor connected
between SETM and GND (see the Typical Operating
Circuit).
Table 1. ENM1/ENM2 States
current by 3.125% (1/32), so after one pulse, the LED
current is 96.9% (or 31/32) x I LED . The 31st pulse
reduces the current to 0.03125 x I LED . The 32nd pulse
sets the LED current back to I LED . Figure 1 shows a
timing diagram for single-wire pulse dimming. Because
soft-start is longer than the initial t HI , apply dimming
pulses quickly upon startup (after initial t HI ) to avoid
LED current transitioning through full brightness.
Simple On/Off Control
If dimming control is not required, connect ENM1 to
ENM2 for simple on/off control. Drive both ENM1 and
ENM2 to a logic-level high to turn on the main LEDs.
Drive both ENM1 and ENM2 to a logic-level low to turn
off the main LEDs. ENF is the simple on/off control for
the flash LEDs. Drive ENF to a logic-level high to turn
on the flash LEDs. Drive ENF to a logic-level low to turn
off the flash LEDs. In this case, LED current is set by
the values of R SETM and R SETF .
ENM1/ENM2 STATES
ENM1 = low, ENM2 = low
ENM1 = high, ENM2 = high
BRIGHTNESS
Shutdown
Full brightness
M1–M6
CURRENT
0
230 x I SETM
Driving Fewer than Eight LEDs
When driving fewer than eight LEDs, two connection
schemes can be used. The first scheme is shown in
Figure 3 where LED drivers are connected together.
Setting the Flash Output Current
SETF controls the F1, F2 regulation current. Current
flowing into F1 and F2 is a multiple of the current flow-
ing out of SETF:
I F1 = I F2 = N x (0.6V / R SETF )
where N = 1380.
Single-Wire Pulse Dimming
For more dimming flexibility or to reduce the number of
control traces, the MAX8645X/MAX8645Y support serial
pulse dimming. Connect ENM1 and ENM2 together to
enable single-wire pulse dimming of the main LEDs (or
ENF only for single-wire pulse dimming of the flash
LEDs). See Figure 2. When ENM1 and ENM2 (or ENF)
go high simultaneously, the main (or flash) LEDs are
enabled at full brightness. Each subsequent low-going
pulse (500ns to 250μs pulse width) reduces the LED
This method allows increased current through the LED
and effectively allows total LED current to be I LED multi-
plied by the number of connected drivers. The second
method of connection is shown in Figure 4 where stan-
dard white LEDs are used and fewer than eight are
connected. This scheme does not alter current through
each LED but ensures that the unused LED driver is
properly disabled.
Input Ripple
For LED drivers, input ripple is more important than out-
put ripple. Input ripple is highly dependent on the
source supply’s impedance. Adding a lowpass filter to
the input further reduces input ripple. Alternately,
increasing C IN to 22μF cuts input ripple in half with only
a small increase in footprint. The 1x mode always has
very low input ripple.
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8645YETI+ | 功能描述:LED照明驱动器 1x/1.5x/2x White LED Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX8645YETI+T | 功能描述:LED照明驱动器 1x/1.5x/2x White LED Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX8645YEVKIT | 制造商:Maxim Integrated Products 功能描述:1X/1.5X/2X CHARGE PUMP WITH 6 LEDS - Rail/Tube 制造商:Rochester Electronics LLC 功能描述: |
| MAX8646ETG+ | 功能描述:直流/直流开关调节器 6A 2MHz Step-Down Regulator w/Switch RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX8646ETG+T | 功能描述:直流/直流开关调节器 6A 2MHz Step-Down Regulator w/Switch RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
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