MAX8934DET データシートの表示（PDF） - Maxim Integrated

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MAX8934DET

Dual-Input Linear Chargers, Smart Power Selector with Advanced Battery Temperature Monitoring

Maxim Integrated 

Dual-Input Linear Chargers, Smart Power Selector

with Advanced Battery Temperature Monitoring

Pin Description (continued)

PIN

16

17

18, 19

20, 21

22

23, 24

25

26

27

28

—

NAME

THMSW

FUNCTION

Thermistor Pullup Supply Switch. Drive THMEN high to enable the THMSW, shorting the THMSW output

to LDO. Drive THMEN low to open the THMSW switch. THMSW is always on when a valid input source

is present and the battery is being charged. When no input source is present, THMSW is controlled by

THMEN. THMSW is also active when the battery is being discharged, so that the battery temperature

can be monitored for an overtemperature condition.

LDO

Always-On Linear Regulator Output. LDO is the output of an internal always-on 3.3V LDO that provides

power to external circuitry. The LDO output provides up to 30mA of current for indicator LEDs or other

loads. LDO remains active even when only a battery is present, so that the thermistor monitor circuitry

can be activated when the battery is being discharged, and other circuitry can remain powered.

Connect a 1FF ceramic capacitor from LDO to GND.

USB

USB Power Input. USB is capable of delivering up to 0.5A to SYS in the MAX8934A/MAX8934B/

MAX8934C/MAX8934E. The USB current limit is set with PEN2 and USUS. See Table 2a. In the

MAX8934D, USB is capable of delivering up to 1.5A to SYS. Both USB pins must be connected together

externally. Connect a 4.7FF ceramic capacitor from USB to GND.

BATT

CHG

Battery Connection. Connect the positive terminal of a single-cell Li+ battery to BATT. The battery

charges from SYS when a valid source is present at DC or USB. BATT powers SYS when neither DC nor

USB power is present, or when the SYS load exceeds the input current limit. Both BATT pins must be

connected together externally.

Charger Status Output. The CHG active-low, open-drain output pulls low when the battery is in fast

charge or prequal. Otherwise, CHG is high impedance.

System Supply Output. SYS is connected to BATT through an internal 40mI system load switch when

DC or USB are invalid, or when the SYS load is greater than the input current limit.

When a valid voltage is present at DC or USB, SYS is limited to 5.3V (MAX8934A) or 4.35V (MAX8934B/

SYS

MAX8934C/MAX8934D/MAX8934E). When the system load (ISYS) exceeds the DC or USB current limit,

SYS is regulated to 68mV below VBATT and both the input and the battery service the SYS load.

Bypass SYS to GND with a 10FF ceramic capacitor. Both SYS pins must be connected together

externally.

OT

DOK

UOK

FLT

EP

Battery Overtemperature Flag. The OT active-low, open-drain output pulls low when THMEN is high and

the battery temperature is R +75NC.

DC Power-OK Output. The DOK active-low, open-drain output pulls low when a valid input is detected

at DC.

USB Power-OK Output. The UOK active-low, open-drain output pulls low when a valid input is detected

at USB.

Fault Output. The FLT active-low, open-drain output pulls low when the battery timer expires before

prequal or fast charge complete.

Exposed Pad. Connect the exposed pad to GND. Connecting the exposed pad does not remove the

requirement for proper ground connections to the appropriate pins.

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