MAX6427 View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX6427

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

Maxim Integrated 

Low-Power, Single/Dual-Level Battery Monitors

with Hysteresis

VBATT

VDD

LTHIN

HTHIN

VDD

EXTERNAL

RESISTOR-

DIVIDER

615

+

-

mV

( ) ARE FOR THE MAX6435

Figure 3. MAX6433/MAX6434/MAX6435 Functional Diagram

R

Q

S

Q

LBO

(LBO)

LBO TIMEOUT

PERIOD

Hysteresis

Hysteresis increases the comparator’s noise margin by

increasing the upper threshold or decreasing the lower

threshold (see Figure 8). The hysteresis prevents the

output from oscillating (chattering) when BATT or VDD

is near the low-battery threshold. This is especially

important for applications where the load on the battery

creates significant fluctuations in battery voltages.

Fixed Hysteresis (MAX6427–MAX6432)

The MAX6427/MAX6428/MAX6429 total hysteresis is the

difference between the factory-trimmed VLTH and VHTH.

For the MAX6430/MAX6431/MAX6432, the total hysteresis

is the difference between the factory-trimmed VHTH- and

VHTH+ or VLTH- and VLTH+ values, approximately 5%.

Adjustable Hysteresis (MAX6433–MAX6438)

Figure 7 shows the correct connections for the external

resistor-dividers. To adjust the low-battery threshold

and hysteresis connect resistor R1 between VDD and

LTHIN, resistor R2 between LTHIN and HTHIN, and R3

between HTHIN and GND. The hysteresis for the

MAX6433–MAX6438 is determined by an external resis-

tor-divider network (see Resistor-Value Selection sec-

tion of Applications Information). The hysteresis for the

MAX6436/MAX6437/MAX6438 is the differences

between VHTHIN- and VHTHIN+ (~5%) or VLTHIN- and

VLTHIN+ (~5%).

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