Detailed Description

These battery monitors have an active-low output that

asserts when the input falls below a set voltage. They

also offer hysteresis for noise immunity, and to remove

the possibility of output chatter due to battery terminal

voltage recovery after load removal. They are available

with one or two monitors per package, with push-pull or

open-drain outputs, and with internally set or externally

adjustable hysteresis (dual-channel devices offer only

internally fixed hysteresis). Figures 1, 2, and 3 show

block diagrams and typical connections. See the

Selector Guide for details.

Low-Battery Output

All devices are offered with either push-pull or open-

drain outputs (see the

Selector Guide). The MAX6781

has one push-pull output and one open-drain output,

configured as in Table 1.

On all devices with open-drain outputs an external

pullup resistor is required. The open-drain pullup resis-

tor can connect to an external voltage up to +6V,

regardless of the voltage at BATT.

Low-Power, 1%-Accurate Battery

Monitors in µDFN and SC70 Packages

6

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Table 1. MAX6781 Outputs

DEVICE

LBO1

LBO2

MAX6781

Push-Pull

Open-Drain

LBI1

LBO1

0

1

BATT

GND

LBI2

LBO2

0

1

MAX6779

MAX6780

MAX6781

HYSTERESIS

CONTROL

Figure 2. Dual-Channel Fixed-Hysteresis Block Diagram

LBI

LBO

0

1

BATT

GND

MAX6775

MAX6776

HYSTERESIS

CONTROL

Figure 1. Single-Channel Fixed-Hysteresis Block Diagram

LBL

LBO

0

1

LBH

BATT

GND

MAX6777

MAX6778

Figure 3. Single-Channel Adjustable-Hysteresis Block Diagram