M62212P/FP/GP
Application Circuit
L
V
IN
+
C
IN
8
1
R2
4
C
OSC
M62212P/FP/GP
7
6
5
+
3
2
D
R1
+
C
OUT
V
OUT
Figure 1 STEP-DOWN Converter with Current Buffer Transistor
Function Description
1) Soft start (The peripheral circuit is shown in Figure 1)
When the power is turned ON, input terminal IN is at 0 V level. Therefore, the FB terminal is fixed to High level.
The DTC terminal goes up gradually starting from 0 V due to the internal charge current and the external C
DTC
.
When the level of DTC terminal reaches the lower limit of the triangular wave of the oscillator, PWM comparator
and the output circuit go into operation causing the output voltage,
"V
O
"
of the DC/DC converter to rise. The charge
current is designed to be approximately 45
µA.
FB
DTC
1.0 V
OSC
0.45 V
OFF
External Tr collector
ON
Figure 2
Rev.2.00 Jun 14, 2006 page 4 of 8
RENESAS [ RENESAS TECHNOLOGY CORP ]
