Low-Power, Adjustable Battery Monitors with

Hysteresis and Integrated µP Reset

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7

5%

HYST

LTH

DETECT

DETECT

5%

HYST

HTH

DETECT

LTHIN

HTHIN

615mV

LBO

TIMEOUT

PERIOD

RESET

TIMEOUT

PERIOD

LBOL

LBOH

RESET

MAX6848

1.23V

Figure 1b. MAX6848 Functional Diagram

MAX6847

LTH

DETECT

HTH

DETECT

R

S

Q

LBO TIMEOUT

PERIOD

RESET

TIMEOUT

PERIOD

DETECT

LTHIN

HTHIN

LBO

RESET

615mV

Q

MR

1.23V

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-

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

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

monitors provide two low-battery outputs: LBOH and

and remains asserted for at least 150ms after HTHIN

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

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.