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参数资料
| 型号： | MAX8939EWV+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 20/45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
Detailed Description
Startup and Power States
To guarantee the correct startup of the MAX8939/
MAX8939A/MAX8939B, an internal power-on reset is
generated after the first connection of the battery. This
resets the I 2 C registers to the default values. The ICs
are then in reset state. The reset state is a low power
level, where the I 2 C interface is disabled and it is not
possible to read or write to any register. The ICs stay in
reset state as long as V BATT is below the UVLO upper
threshold. When the battery voltage exceeds the UVLO
upper threshold, the ICs enter the standby state and the
I 2 C bus can be written to. The typical response time of
the UVLO detection is 50μs.
The UVLO upper threshold can be reached three ways:
? Fully charge battery is inserted and RESET is logic-high.
? RESET changes from logic-low to logic-high and
V BATT > V UVLO_UPPER .
? Charger is detected and CHG is logic-low.
Standby
Standby is a low-power state where the I 2 C is ready
for read/write operations and enables the different
power units (Table 1). If a unit is enabled through I 2 C or
CHG_IN is powered, the bandgap and internal oscillator
are started and the ICs move to the active state. The ICs
stay in the active state until the last unit (including the
charger) is disabled.
Reset
The ICs enter the reset state when the battery voltage
drops below the UVLO lower threshold. In reset, all reg-
isters are reset except the STATUS and EVENT registers
that retain their values as long as the battery is con-
nected. In reset, all power units are disabled and only
the UVLO and CHG_IN detection circuitry is active. If a
fully charged battery is inserted or a charger is detected,
the ICs enter standby. If a valid charger is connected,
the state machine enables the PWR_ON_CMP generator
and an interrupt is sent to the host when above the UVLO
upper threshold. When a valid charger is detected while
in the reset state, the SAFE_OUT LDO is enabled and the
charger begins precharging the battery.
Shutdown
The shutdown state is an extremely low-power state. To
enter shutdown, hold RESET logic-low.
20
In shutdown, all the internal blocks are disabled except
the CHG_IN detection. If CHG_IN is asserted, the ICs
move to the reset state and starts charging with the
default settings. When entering from shutdown, the
charger is reset and the PWR_ON_CMP generator is
enabled. If the charger is removed, the ICs move back
to the shudown state if RESET is still logic-low.
Charger
The ICs’ charger uses voltage, current, and thermal-
control loops to charge a single Li+ cell and to protect
the battery. A complete charge cycle covers four states:
prequalification (precharge), constant current fast-
charge (CC), constant voltage top-off (CV), and charge
complete (done). If the battery voltage is below 2.55V,
the charger is pre-charging with 90mA until prequalifica-
tion upper threshold is reach or the maximum precharge
time (30min for the MAX8939 or 12min for the MAX8939A
and MAX8939B) reached. The precharge timer is reset
when CHG_IN is reasserted, and the charger starts
charging if the battery voltage is below the precharge
threshold. When the charger is in precharge mode,
an LED indicator (LED3) and the SAFE_OUT LDO are
turned on; all other functions are disabled.
Once the battery voltage has passed the prequalification
upper threshold, the charger enters the fast-charge stage.
An analog soft-start is used when entering fast charge
to reduce inrush current on the input supply. When fast-
charge is in progress, a safety timer is enabled and STATUS
can be read out of register 0x02 bit 4. For the MAX8939/
MAX8939A, the CHG_EN is cleared and starts charging
if CHG_IN is asserted. The MAX8939B clears CHG_EN
only if RESET is logic-low. By pulling RESET logic-high, the
charger is disabled or enabled depending on the state of
the CHG_EN bit. When CHG_IN is asserted, an interrupt
occurs, and the host can control the state of the CHG_IN bit.
The fast-charge current and safety timer are programmable
through the I 2 C interface. The safety timers are reset if the
charger is disabled and start a new cycle when the charger
is enabled. The default battery regulation voltage (V SET ) is
3.6V (MAX8939) or 3.5V (MAX8939A/MAX8939B), but can
be programmed to 4.15V, 4.2V, or 4.25V for the MAX8939,
or 3.85V, 4.05V, or 4.17V for the MAX8939A/MAX8939B.
When the battery voltage reaches V SET , the charger
changes to top-off mode (CV). When entering top-off, an
IRQ is flagged to indicate that the charger is in constant
voltage mode. Top-off mode keeps the voltage constant
and the current falls slowly until the top-off current thresh-
old is reached. An IRQ is flagged to indicate charge is
Maxim Integrated
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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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