has stabilized before power-converter or microproces-

sor activity is enabled.

These devices also have an independent µP supervisor

put. A manual reset function is available to allow the

user to reset the µP with a push-button.

Low-Battery Output

The low-battery outputs are available in active-low

(LBO, LBOL, LBOH, LBOLH), open-drain configura-

tions. The low-battery outputs can be pulled to a volt-

allows the device to monitor and operate from direct

battery voltage while interfacing to higher voltage

microprocessors.

The MAX6439/MAX6440 single-output voltage monitors

provide a single low-battery output, LBO. These fixed-

MAX6442 triple-output voltage monitors provide three

low-battery outputs: LBOH, LBOL, and LBOLH. LBOH

plete before the LBOH/LBOLH timeout period begins.

Reset Output

The MAX6439–MAX6442 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. The MAX6439/MAX6441 have open-

drain reset outputs, while the MAX6440/MAX6442 have

push-pull reset outputs (see Figure 4).

Low-Power, Single-/Dual-Level Battery Monitors

with Hysteresis and Integrated µP Reset

8

_______________________________________________________________________________________

5%

HYST

LTH

DETECT

DETECT

5%

HYST

HTH

DETECT

1.23V

LBO

TIMEOUT

PERIOD

RESET

TIMEOUT

PERIOD

LBOL

LBOH

LBOLH

RESET

MR

MAX6441

Figure 1b. Functional Diagram

MAX6440

LTH

DETECT

HTH

DETECT

R

S

Q

LBO TIMEOUT

PERIOD

RESET

TIMEOUT

PERIOD

DETECT

LBO

RESET

1.23V

Q

MR

Figure 1a. Functional Diagram