MAX6846 View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX6846

Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated µP Reset

Maxim Integrated 

Low-Power, Adjustable Battery Monitors with

Hysteresis and Integrated µP Reset

VDD

LTHIN

HTHIN

VCC

LTH

DETECT

HTH

DETECT

MAX6847

RQ

SQ

LBO TIMEOUT

PERIOD

VDD

LTHIN

HTHIN

LBO

615mV

VCC

VCC

VTH

DETECT

RESET

TIMEOUT

PERIOD

VCC

1.23V

RESET

MR

5%

HYST

LTH

DETECT

5%

HYST

615mV

HTH

DETECT

MAX6848

LBO

TIMEOUT

PERIOD

1.23V

VTH

DETECT

RESET

TIMEOUT

PERIOD

LBOL

LBOH

RESET

Figure 1a. MAX6847 Functional Diagram

Low-Battery Output

The low-battery outputs are available in active-low

(LBO, LBOL, LBOH), open-drain configurations. The

low-battery outputs can be pulled to a voltage indepen-

dent of VCC or VDD, up to 5.5V. This allows the device

to monitor and operate from direct battery voltage while

interfacing to higher voltage microprocessors.

The MAX6846/MAX6847 single-output voltage monitors

provide a single low-battery output, LBO. LBO asserts

when LTHIN drops below VLTH and remains asserted

for at least 150ms after HTHIN rises above VHTH (see

Figure 2). The MAX6848/MAX6849 dual-output voltage

monitors provide two low-battery outputs: LBOH and

LBOL. LBOH asserts when HTHIN drops below VHTH-

and remains asserted for at least 150ms after HTHIN

Figure 1b. MAX6848 Functional Diagram

rises above VHTH+. LBOL asserts when LTHIN drops

below VLTH- and remains asserted for at least 150ms

after LTHIN rises above VLTH+ (see Figure 3). For fast-

rising VDD input, the LBOL timeout period must com-

plete before the LBOH timeout period begins.

Reset Output

The MAX6846–MAX6849 provide an active-low reset

output (RESET). RESET is asserted when the voltage at

VCC falls below the reset threshold level. Reset remains

asserted for the reset timeout period after VCC exceeds

the threshold. If VCC goes below the reset threshold

before the reset timeout period is completed, the inter-

nal timer restarts (see Figure 4). The MAX6846/

MAX6848 have open-drain reset outputs, while the

MAX6847/MAX6849 have push-pull reset outputs.

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