MAX4919B 데이터 시트보기 (PDF) - Maxim Integrated

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MAX4919B

Battery Power-Up Logic with Overvoltage and Overcurrent Protection

Maxim Integrated 

Battery Power-Up Logic with Overvoltage

and Overcurrent Protection

ADAPTER

VOLTAGE

IN

ACOK

OVLO

UVLO

25ms DEBOUNCE PERIOD

t1SHAC

ACOK

ONE-SHOT

P2

OFF

STATUS

Figure 1. ACOK One-Shot Timing Diagram

GN1 Driver

An internal 5.5V supply powers the on-chip charge

pump used to drive GN1 above IN, allowing the use of

a low-cost nFET. The GN1 voltage is approximately two

times VIN until VIN exceeds 5.5V, at which point, GN1

clamps to 9.5V (MAX4919B/MAX4920B) or 8.1V

(MAX4921B).

ACOK

ACOK is an active-low open-drain output that asserts

when VUVLO <VIN < VOVLO for the 25ms debounce

period. ACOK deasserts immediately to overvoltage

and undervoltage faults. Connect a pullup resistor from

ACOK to the logic I/O voltage of the host system.

PWR_ON

PWR_ON is one of the logic inputs that enables the

internal 1.8A switch. Drive PWR_ON high to turn on the

internal switch. PWR_ON also controls the logic output

OFF

ON

ONOK. The ONOK open-drain output is the inverse of

the PWR_ON input state (see Figure 5). Note that

ONOK is high impedance when VIN < VUVLO, and VBTI

< 2.82V (typ). If VBTI is greater than 2.15V (typ), but

less than 2.82V (typ), PWR_ON and ONOK are dis-

abled and ONOK pulls high. When BTI rises above

2.82V (typ) again, PWR_ON is again enabled and

ONOK goes back to its previous logic level before a

low condition at BTI (see Figure 6).

Battery Switchover

An internal 1.8A (min) pFET with a 100mΩ (typ) RON

connects BTI to the load at BTO. The internal battery

switchover FET turns on when either HP_PWR,

PWR_ON, or PWR_HOLD is high. Note that when BTI

< 2.15V, the internal switch remains inactive, regard-

less of the logic control signals.

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