MAX6437UT+T Maxim Integrated Products, MAX6437UT+T Datasheet - Page 12

• Manufacturer Part Number: MAX6437UT+T
• Description: IC MONITOR BAT LP SOT23-6
• Manufacturer: Maxim Integrated Products

Specifications of MAX6437UT+T

• Function: Battery Monitor
• Battery Type: Alkaline, Li-Ion, NiCd, NiMH
• Voltage - Supply: 1 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MAX6437UT+T; MAX6437UT+TTR

Low-Power, Single/Dual-Level Battery Monitors
with Hysteresis
(See Figure 5)
Use the following steps to determine values for R1, R2,
and R3 of Figure 8.
1) Choose a value for R
2) Calculate R3 based on R
3) Calculate R2 based on R
4) Calculate R1 based on R
Figure 9. DC-to-DC Converter Application
12
BATT
R
R3. Because the MAX6433/MAX6434/MAX6435
have very high input impedances, R
up to 5MΩ.
upper trip point:
desired lower trip point:
R
3
V
V
V
Resistor-Value Selection (Programming
______________________________________________________________________________________
REF
TRIPLOW
TRIPHIGH
TOTAL
=
V
=
REF
V
R
R
V
MAX6431
=
TRIPHIGH
2
1
V
LTHIN
=
GND
BATT
=
Applications Information
×
R
=
V
=
V
1
MAX6433/MAX6434/MAX6435
LTH
HTL
R
R
LBOH
+
LBOL
615
TOTAL
TOTAL
the Adjustable Thresholds)
=
R
=
V
2
mV
=
V
HTHIN
TRIPLOW
TOTAL
+
V
V
REF
REF
×
TOTAL
R
=
−
SHDN
IN
3
R
R



=
585
DC/DC



TOTAL
, the sum of R1, R2, and
2
TOTAL
R
R
615
1
1
TOTAL
−
, R3, and R2:
R
mV
V
+
OUT
+
R
mV
2
TRIPHIGH
3
R
R
+
R
−
2
and the desired
×
2
3
R
, R3, and the
R
+
R
+
TOTAL
3
3
TOTAL
R
NMI
R
3
3






V
GND
CC
µP
can be
(See Figure 6)
Use the following steps to determine values for R1, R2,
and R3 of Figure 8.
1) Choose a value for R
2) Calculate R3 based on R
3) Calculate R2 based on R
4) Calculate R1 based on R
The MAX6430/MAX6431/MAX6432 and MAX6436/
MAX6437/MAX6438 dual-output battery monitors can
be used in conjunction with a step-up DC-to-DC con-
verter to power 5V microprocessor systems using a sin-
gle Li+ cell or two to three alkaline/NiCd/NiMH cells
(Figure 9). The LBOH output indicates that the battery
voltage is weak, and is used to warn the microproces-
sor of potential problems. Armed with this information
the microprocessor can reduce system power con-
sumption. The LBOL output indicates the battery is
empty, and system power should be disabled. By con-
necting LBOL to the SHDN pin of the DC-to-DC con-
verter, power to the microprocessor is removed.
R
R3. Because the MAX6436/MAX6437/MAX6438
have very high input impedances, R
up to 5MΩ.
upper trip point:
desired lower trip point:
3
R
V
V
V
LBOL
LBOH
V
REF
TRIPLOW
TRIPHIGH
TOTAL
=
HTH+
V
REF
=
/
/
LBOL OUTPUT
LBOH OUTPUT
= V
V
TRIPHIGH
V
=
R
DC-to-DC Converter Application
LTHI
=
=
×
HTH-
1
R
V
MAX6436/MAX6437/MAX6438
V
585
1
R
LTH
=
HTL-
N-
TOTAL
+
R
✕
V
mV R
-
=
TRIPLOW
TOTAL
R
1.05, V
=
2
V
=
TOTAL
×
HTHIN
+
V
V
TOTAL
=
:
REF
TOTAL
REF
:
R
−
LTH+
585
3
, the sum of R1, R2, and
-
TOTAL



R



=
R
TOTAL
2
, R3, and R2:
R
mV
585
1
V
1
−
= V
TRIPHIGH
−
R
+
+
R
2
R
mV
and the desired
×
3
LTH-
3
R
R
R
+
, R3, and the
2
R
2
3
TOTAL
TOTAL
R
+
+
✕
3
R
1.05
R
3
3
can be





