
CS5160
http://onsemi.com
10
Figure 8. CS5160 Peak–to–Peak Ripple on VOUT = 2.8 V,
IOUT = 13 A (Heavy Load)
M 1.00
s
Trace 1– Regulator Output Voltage (10 mV/div.)
Trace 2– Inductor Switching Node (5.0 V/div.)
Transient Response
The CS5160 V2 control loop’s 100 ns reaction time
provides unprecedented transient response to changes in
input voltage or output current. Pulse by pulse adjustment of
duty cycle is provided to quickly ramp the inductor current
to the required level. Since the inductor current cannot be
changed instantaneously, regulation is maintained by the
output capacitor(s) during the time required to slew the
inductor current.
For best transient response, a combination of a number of
high frequency and bulk output capacitors are usually used.
If the maximum on time is exceeded while responding to
a sudden increase in load current, a normal off time occurs
to prevent saturation of the output inductor.
Figure 9. CS5160 Pentium III Converter Output
Voltage Response to a 12 A Load Pulse
100
s/div.
Trace 2– Regulator Output Voltage (output set for 1.55 V, 20 mV/div.)
Figure 10. CS5160 Pentium III Converter Output
Voltage Response to a 0 to 12 A Load Increase
10
s/div.
Trace 2– Regulator Output Voltage (output set for 1.55 V, 20 mV/div.)
Trace 1– Inductor Switching Node (5.0 V/div.)
Figure 11. CS5160 Pentium III Converter Output
Voltage Response to a 12 to 0 A Load Decrease
10
s/div.
Trace 2– Regulator Output Voltage (output set for 1.55 V, 20 mV/div.)
Trace 1– Inductor Switching Node (5 V/div.)
PROTECTION AND MONITORING FEATURES
VCC1 Monitor
To
maintain
predictable
startup
and
shutdown
characteristics an internal VCC1 monitor circuit is used to
prevent the part from operating below 8.95 V minimum
startup. The VCC1 monitor comparator provides hysteresis
and guarantees a 8.80 V minimum shutdown threshold.
Short Circuit Protection
A lossless hiccup mode short circuit protection feature is
provided, requiring only the Soft Start capacitor to
implement.
If
a
short
circuit
condition
occurs
(VFFB < 1.0 V), the VFFB low comparator sets the FAULT