Datasheet
SLUS486B − AUGUST 2001 − REVISED JULY 2003
11
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APPLICATION INFORMATION
systems with 5-V input only
The circuit pictured in Figure 6 starts up from a 5-V input bus and provides a 6.5-V gate drive to the power
MOSFETs. This circuit uses a charge pump consisting of D
3
, D
4
and C
3
to effectively double the input voltage
and apply this to the input of the linear regulator. The regulator then regulates the doubled input voltage to the
6.5-V nominal for VLO.
C
IN
C2
C1
PWM
Input
D1
GND
+5V
VHI
G1
SW
SWS
PVLO
N/C
VDD
VLO
G2S
G2
PGND
AGND
IN
N/C
UCC27222
L1
Cout
Q1
Q2
V
OUT
GND
C4
D3
D4
D2
C3
Figure 6. System Application: 5-V-Only Power Input with 6.5-V Gate Drive Using Charge Pump Circuit