Datasheet
MAX6775–MAX6781
Low-Power, 1%-Accurate Battery
Monitors in µDFN and SC70 Packages
8 _______________________________________________________________________________________
Selector Guide
PART LBO OUTPUT OUTPUT TYPE HYSTERESIS PIN-PACKAGE
MAX6775XK_+T Single Push-Pull Fixed 5 SC70
MAX6775LT_+T Single Push-Pull Fixed 6 µDFN
MAX6776XK_+T Single Open-Drain Fixed 5 SC70
MAX6776LT_+T Single Open-Drain Fixed 6 µDFN
MAX6777XK+T Single Push-Pull Adjustable 5 SC70
MAX6777LT+T Single Push-Pull Adjustable 6 µDFN
MAX6778XK+T Single Open-Drain Adjustable 5 SC70
MAX6778LT+T Single Open-Drain Adjustable 6 µDFN
MAX6779LT_+T Dual Push-Pull Fixed 6 µDFN
MAX6780LT_+T Dual Open-Drain Fixed 6 µDFN
MAX6781LT_+T Dual Mixed Fixed 6 µDFN
Calculating an External
Hysteresis Resistive Divider
Setting the hysteresis externally requires three external
resistors, as shown in Figure 3. Select R
H
using the fol-
lowing formula:
where e
A
is the allowable error due to input leakage
current (typically 0.005 or less), V
BATT_RISING
is the
desired rising threshold, and I
L
is the worst-case leak-
age current (5nA). Then calculate R
LO
(which is the
sum of R
L
and R
HYST
):
where V
LBI
is 1.222V and V
BATT_FALLING
is the desired
falling threshold. Calculate R
L
using:
and finally, calculate R
HYST
:
Monitoring a Battery Voltage Higher
Than the Allowable V
BATT
For monitoring higher voltages, supply power to BATT
that is within the specified supply range, and power the
input resistive divider from the high voltage to be moni-
tored. Do not exceed the
Absolute Maximum Ratings
.
Adding External Capacitance to
Reduce Noise and Transients
If monitoring voltages in a noisy environment, add a
bypass capacitor of 0.1µF from BATT to GND as close
as possible to the device. For systems with large tran-
sients, additional capacitance may be required. A small
capacitor (<1nF) from LBI_ to GND may provide addi-
tional noise immunity.
RRR
HYST LO L
=−
R
VRR
V
L
LBI H LO
BATT RISING
=
×+
()
_
R
VR
VV
LO
LBI H
BATT FALLING LBI
=
×
−
_
R
eV
I
H
A BATT RISING
L
≤
×
_