AD5100
Rev. A | Page 32 of 36
BATTERY MONITORING WITH FAN CONTROL
V
4MON
can be used with V
4OUT
in tandem to form a simple PWM
control circuit. For example, as shown in Figure 26, when a
temperature sensor output connects to the V
4MON
input, with
the proper threshold level set, V
4OUT
outputs high whenever the
temperature goes above the threshold. This turns on the FET
switch, which activates the fan. When V
TEMP
drops below the
threshold, V
4OUT
decreases, which turns off the fan.
BATTERY STATE OF CHARGE INDICATOR AND
SHUTDOWN EARLY WARNING MONITORING
In the automotive application, the system designer may set the
battery threshold to the lowest level to allow an automobile to
start at the worst-case condition. If the battery remains at the
low voltage level, it is indeed a poor battery. However, there is
no way to warn the driver. As a result, the system designer can
use V
4OUT
as the battery warning indicator. By stepping down
the battery voltage monitored at V
4MON
, the LED is lit, which
gives a battery replacement warning. The circuit is shown in
Figure 28.
05692-027
AD5100
V
2MON
V
3MON
V
4MON
MR
WDI
SDA
SCL
V
1MON
V
4OUT
SHDNWARN
SHDN
RESET
WDI
MR
BATTERY
IGNITION
V
REG
V
TEMP
MR
WDI
CLK
V
REG
V
REG
BATTERY
SD
MICROPROCESSOR
CLK MISO/MOSI
PA
TMP35
VTEMP
Figure 26. Power Amp Monitoring and Fan Control
05692-028
TEMP
V
4OUT
NOTES
1. V
4MON
RESET DISABLED.
4MON
THRESHOLD
Figure 27. V
4OUT
with Respect to V
TEMP
, with V
4MON
RESET
Disabled in Circuit Shown in Figure 26
05692-029
AD5100
V
4MON
SDA
SCL
V
4OUT
SHDNWARN
SHDN
V
1MON
BATTERY
V
2MON
IGNITION
CLK
MICROPROCESSOR
CLK MISO/MOSI
Figure 28. Battery State of Charge Indication
