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参数资料
| 型号： | MAX8939EWV+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 23/45页 |
| 文件大小： | 0K |
| 描述： | IC PWR MGMT HANDSETS 30WLP |
| 标准包装： | 2,500 |
| 应用： | 充电泵，无线设备 |
| 输入电压： | 2.9 V ~ 5.5 V |
| 输出数： | 7 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | * |
| 封装/外壳： | * |
| 供应商设备封装： | * |
| 包装： | * |
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MAX8939/MAX8939A/MAX8939B
System Power Management
for Mobile Handset
event is detected, the ICs start pulsing the PWR_ON_
CMP output every 50ms, with a duty cycle of 98%. See
Figure 5.
The event is also signaled by IRQ , which is asserted
when the UVLO upper threshold is reached and the
CHG_DET bit is set in register 0x04 (bit 6). The ICs con-
tinue pulsing PWR_ON_CMP until the EVENT registers
0x04 or 0x03 are read/written to or the charger safety
timer expires. By reading/writing to the EVENT register,
the register is cleared and PWR_ON_CMP and IRQ
returns to high impedance.
The events causing the PWR_ON_CMP activation are
triggered by a rising edge signal that must remain valid
for the duration of a 10ms debounce filter.
RESET_IN
RESET_IN is an active-low input signal to the ICs and is
used to provide a full system reset inside the ICs. As long
as RESET_IN is logic-low, the ICs are not able to do any-
thing (except the charger), until RESET_IN is released.
All registers are cleared except the STATUS and EVENT
registers. When RESET_IN is asserted, the EVENT_B bit
RESET is set. If the CHG_IN voltage is valid and RESET_
IN is logic-low, the charger operates in its default state.
Linear Regulators
The ICs include four low-dropout linear regulators
(LDOs). All LDOs are designed for low dropout, low
noise, high PSRR, and low quiescent current to maximize
battery life. When the battery voltage is above the UVLO
upper threshold, the ICs’ LDOs are ready to be turned on
through the I 2 C interface. The guaranteed current drive
capabilities for the LDOs are 400mA for LDO1, 200mA
for LDO2 and LDO3, and 100mA for LDO4. The output
voltage for each LDO is programmable through the I 2 C
interface from 1.7V to 3.2V in 0.1V steps.
LDO1 can be enabled through a hardware pin
LDO1_EN. By connecting this pin to a logic-high level,
the LDO enables automatically when the UVLO upper
threshold is reached. The LDO can also be controlled
by the LDO1_EN bit of the REG_CONTROL. When the
LDO1_EN bit is written to, the LDO1 enable state reflects
the value written, overriding the state of the LDO1_EN
pin. When the state of the LDO1_EN pin changes, the
LDO1 enable state is determined by the new state of the
LDO1_EN pin, overriding the LDO1_EN bit value. This
allows the system software to reduce quiescent power
consumption by turning off LDO1 without impacting
other logic that may utilize the same hardware control
used for the LDO1_EN pin.
OUT1 Step-Up DC-DC Converter
OUT1 is a fixed-frequency PWM step-up converter.
The converter switches an internal power MOSFET and
synchronous rectifier at a constant 2MHz frequency with
varying duty cycle up to 75% to maintain constant out-
put voltage as the input voltage and load current vary.
Internal circuitry prevents any unwanted subharmonic
switching in the critical step-down/step-up region by
forcing a minimum 8% duty cycle.
OUT1 delivers up to 700mA to the load at a voltage pro-
grammable through I 2 C from 3.5V to 5V in 100mV steps.
Soft-Start OUT1
OUT1 soft-starts by charging C COMP1 with a 100 F A
current source. During this time, the internal MOSFET
is switching at the minimum duty cycle. Once V COMP1
rises above 1V, the duty cycle increases until the output
voltage reaches the desired regulation level. COMP1
is pulled to ground with a 30 I internal resistor during
UVLO or shutdown.
OUT2 White LED Driver
OUT2 is the output from the step-up DC-DC converter
for driving white LEDs. The converter is able to drive up
to 60mA at up to 28V. The step-up converter is adaptive
connected to the two low-dropout LED current regula-
tors. The step-up converter operates at a fixed 2MHz
switching frequency, enabling the use of very small
external components to achieve a compact circuit area.
For improved efficiency, the step-up converter automati-
cally operates in pulse-skipping mode at light loads.
I LED_ = FULL SCALE
256ms
512ms
1024ms
2048ms
I LED_ = ? SCALE
0mA
I LED_ = FULL SCALE
I LED_ = ? SCALE
0mA
256ms
512ms
1024ms
2048ms
Figure 6. Ramp-Up/Ramp-Down
Maxim Integrated
23
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| MAX893LESA-T | 功能描述:电源开关 IC - USB 1.2A Current-Limited High-Side PCh Switch RoHS:否 制造商:Micrel 电源电压-最小:2.7 V 电源电压-最大:5.5 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:SOIC-8 封装:Tube |
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