CS8101
APPLICATION NOTES
V
BAT
0.1
mF
500 kW
V
IN
V
OUT
V
CC
C
OUT
mP
CS8101
ENABLE
RESET
R
RST
GND
RESET
C
RST
I/O Port
Q1
100 kW
500 kW
SWITCH
100 kW
Figure 6. Microprocessor Control of CS8101 Using External Switching Transistor Q1
The ENABLE pin of the CS8101 can be tied to the battery
voltage provided a series resistor is used as shown in Figure 7.
The maximum allowed voltage on the ENABLE pin without
the resistor is 10 V. Direct voltages greater than 10 V applied
to the pin without the series resistor may damage the device.
The system designer should note the turn−on threshold (typ
1.4 V) is on the ENABLE pin. The threshold will be higher
on the other side of R
ENABLE
.
R
ENABLE
10 k
V
BAT
V
IN
C
IN
*
0.1
mF
V
OUT
CS8101
RESET
ENABLE
R
RST
C
OUT
**
10
mF
*C
IN
required if regulator is located far from the power supply filter
.
*C
OUT
required for stability. Capacitor must operate at
minimum temperature expected.
ENABLE
60 k
0.64 V
Figure 8. Test and Application Circuit Showing
Output Compensation
ON/OFF
Control
50 k
Figure 7. Using the ENABLE pin with V
BAT
STABILITY CONSIDERATIONS
The output or compensation capacitor helps determine
three main characteristics of a linear regulator: start−up
delay, load transient response and loop stability.
The capacitor value and type should be based on cost,
availability, size and temperature constraints. A tantalum or
aluminum electrolytic capacitor is best, since a film or
ceramic capacitor with almost zero ESR can cause
instability. The aluminum electrolytic capacitor is the least
expensive solution, but, if the circuit operates at low
temperatures (−25°C to −40°C), both the value and ESR of
the capacitor will vary considerably. The capacitor
manufacturers data sheet usually provides this information.
The value for the output capacitor C
OUT
shown in Figure 8
should work for most applications, however it is not
necessarily the optimized solution.
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