MAX6781 Maxim Integrated Products, MAX6781 Datasheet - Page 8

• Manufacturer Part Number: MAX6781
• Description: 1%-Accurate Battery Monitors
• Manufacturer: Maxim Integrated Products

Setting the hysteresis externally requires three external
resistors, as shown in Figure 3. Select R
lowing formula:
where e
current (typically 0.005 or less), V
desired rising threshold, and I
age current (5nA). Then calculate R
sum of R
where V
falling threshold. Calculate R
Low-Power, 1%-Accurate Battery
Monitors in µDFN and SC70 Packages
8
MAX6775XK_+T
MAX6775LT_+T
MAX6776XK_+T
MAX6776LT_+T
MAX6777XK+T
MAX6777LT+T
MAX6778XK+T
MAX6778LT+T
MAX6779LT_+T
MAX6780LT_+T
MAX6781LT_+T
_______________________________________________________________________________________
LBI
A
L
PART
and R
is the allowable error due to input leakage
is 1.222V and V
R
R
LO
R
H
HYST
L
≤
=
Hysteresis Resistive Divider
=
e
V
):
V
A
BATT FALLING
LBI
V
BATT RISING
×
Calculating an External
V
×
BATT RISING
_
V
BATT_FALLING
(
R
LBI
L
_
LBO OUTPUT
I
L
H
using:
L
+
×
_
Single
Single
Single
Single
Single
Single
Single
Single
is the worst-case leak-
R
Dual
Dual
Dual
R
LO
H
BATT_RISING
−
)
LO
V
LBI
H
(which is the
is the desired
using the fol-
is the
OUTPUT TYPE
Open-Drain
Open-Drain
Open-Drain
Open-Drain
Open-Drain
Push-Pull
Push-Pull
Push-Pull
Push-Pull
Push-Pull
Mixed
and finally, calculate R
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 .
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.
Monitoring a Battery Voltage Higher
Adding External Capacitance to
HYSTERESIS
Adjustable
Adjustable
Adjustable
Adjustable
Reduce Noise and Transients
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
R
HYST
Than the Allowable V
HYST
=
:
R
LO
Selector Guide
−
www.DataSheet4U.com
R
L
PIN-PACKAGE
6 µDFN
6 µDFN
6 µDFN
6 µDFN
6 µDFN
6 µDFN
6 µDFN
5 SC70
5 SC70
5 SC70
5 SC70
BATT