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参数资料
| 型号： | MAX8645YETI+ |
| 厂商： | Maxim Integrated |
| 文件页数： | 9/14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： | 75 |
| 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： | 管件 |
| 工作温度： | -40°C ~ 85°C |
| 产品目录页面： | 1424 (CN2011-ZH PDF) |
1x/1.5x/2x White LED Charge Pumps with Two
LDOs in 4mm x 4mm TQFN
Pin Description (continued)
PIN
23
24
25
26
27
28
—
NAME
C1P
PGND
OUT
C2P
C2N
P1
EP
FUNCTION
Transfer Capacitor 1 Positive Connection. Connect a 1μF ceramic capacitor between C1P and C1N.
During shutdown, if OUT > IN, C1P is shorted to OUT. If OUT < IN, C1P is shorted to IN.
Power Ground. Connect PGND to system ground. PGND is used for charge-pump switching currents.
Charge-Pump Output. Bypass OUT to GND with a 10μF ceramic capacitor. Connect to the anodes of
all the LEDs. OUT is internally pulled to ground through a 5k Ω resistor during shutdown.
Transfer Capacitor 2 Positive Connection. Connect a 1μF ceramic capacitor between C2P and C2N.
During shutdown, if OUT > IN, C2P is shorted to OUT. If OUT < IN, C2P is shorted to IN.
Transfer Capacitor 2 Negative Connection. Connect a 1μF ceramic capacitor between C2P and C2N.
C2N is internally shorted to IN during shutdown.
Default Output-Voltage Select Input. P1 and P2 set the LDO1 and LDO2 voltages to one of nine
combinations (Table 2). P1 is high impedance in an off condition and shortly after in an on condition.
Exposed Paddle. Connect to GND and PGND.
Detailed Description
The MAX8645X/MAX8645Y charge pumps drive up to
six white LEDs in the main display for backlighting and
up to two white LEDs for flash, all with regulated con-
stant current for uniform intensity. By utilizing adaptive
1x/1.5x/2x charge-pump modes and very-low-dropout
current regulators, they achieve high efficiency over the
1-cell lithium-battery input voltage range. 1MHz fixed-
frequency switching allows for tiny external compo-
nents and low input ripple. Two on-board 200mA
programmable-output-voltage LDOs are provided to
meet camera-module requirements.
1x to 1.5x Switchover
When V IN is higher than V OUT , the MAX8645X/
MAX8645Y operate in 1x mode and V OUT is pulled up
to V IN . The internal current regulators regulate the LED
current. As V IN drops, V M_ (or V F_ ) eventually falls
below the switchover threshold of 100mV and the
MAX8645X/MAX8645Y start switching in 1.5x mode.
When the input voltage rises above V OUT by approxi-
mately 50mV, the MAX8645X/MAX8645Y switch back to
1x mode.
1.5x to 2x Switchover
When V IN is less than V OUT but greater than 2/3 V OUT ,
the MAX8645X/MAX8645Y operate in 1.5x mode. The
internal current regulators regulate the LED current. As
V IN drops, V M_ (or V F_ ) eventually falls below the
switchover threshold of 100mV, and the MAX8645X/
MAX8645Y start switching in 2x mode. When the input
voltage rises above 2/3 V OUT by approximately 50mV,
the MAX8645X/MAX8645Y switch back to 1.5x mode.
Soft-Start
The MAX8645X/MAX8645Y include soft-start circuitry to
limit inrush current at turn-on. Once the input voltage is
applied, the output capacitor is charged directly from
the input with a ramped current source (with no charge-
pump action) until the output voltage approaches the
input voltage. Once the output capacitor is charged,
the charge pump determines if 1x, 1.5x, or 2x mode is
required. In the case of 1x mode, the soft-start is termi-
nated and normal operation begins. In the case of 1.5x
or 2x mode, soft-start operates until the lowest voltage
of M1–M6 and F1, F2 reaches regulation. If the output
is shorted to ground or is pulled to less than 1.25V, the
output current is limited by soft-start.
True Shutdown? Mode
When ENM1, ENM2, and ENF are simultaneously held
low for 2.5ms or longer, the MAX8645X/MAX8645Y are
shut down and put in a low-current shutdown mode,
and the input is isolated from the output. OUT is inter-
nally pulled to GND with 5k Ω during shutdown.
Thermal Derating
The MAX8645X/MAX8645Y limit the maximum LED cur-
rent depending on the die temperature. The maximum
LED current is set by the R SETM and R SETF resistors.
Once the temperature reaches +40°C, the LED current
decreases by 1.7%/°C. Due to the package’s exposed
paddle, the die temperature is always very close to the
PCB temperature.
The temperature derating function allows the LED cur-
rent to be safely set higher at normal operating temper-
atures, thereby allowing either a brighter display or
fewer LEDs to be used for normal display brightness.
True Shutdown is a trademark of Maxim Integrated Products, Inc.
_______________________________________________________________________________________
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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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