CS51031 View Datasheet(PDF) - ON Semiconductor
Part Name
Description
Manufacturer
CS51031 Datasheet PDF : 10 Pages
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CS51031
COSC
VREF
IC
7IC
1.5 V
VCC
VCC
VCCOK
VREF = 3.3 V
G3
IT
CS
IT
IT
55
5
1.5 V
Oscillator
+ Comparator
A1
−
G1
2.5 V
VC
RG
VGATE
Flip−Flop
RQ
F2
G2
SQ
VFB
Comparator
A6
1.25 V
VGATE
PGND
VFB
VREF
3.3 V
0.7 V
Hold Off
Comp
Fault
Comp 1.15 V
G4
CS Charge
Sense
Comparator
A4
CS
+ Comparator
A2
−
RQ
F1
2.5 V
2.4 V
G5
SQ
Slow Discharge
Flip−Flop
−
A3
+ Slow Discharge
Comparator
2.3 V
GND
Figure 2. Block Diagram
CIRCUIT DESCRIPTION
THEORY OF OPERATION
Control Scheme
The CS51031 monitors the output voltage to determine
when to turn on the P−Ch FET. If VFB falls below the internal
reference voltage of 1.25 V during the oscillator’s charge
cycle, the P−Ch FET is turned on and remains on for the
duration of the charge time. The P−Ch FET gets turned off
and remains off during the oscillator’s discharge time with
the maximum duty cycle to 80%. It requires 7.0 mV typical,
and 20 mV maximum ripple on the VFB pin is required to
operate. This method of control does not require any loop
stability compensation.
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