SRP Hitachi Semiconductor, SRP Datasheet - Page 11

• Manufacturer Part Number: SRP
• Description: High Speed Current Mode PWM Control IC for Switching Power Supply
• Manufacturer: Hitachi Semiconductor

Timing Chart
Input voltage
V
UVL1
Internal signal which
cannot be externally
monitored.
Reference voltage
Vref Pin 8
UVL2
Internal signal which
cannot be externally
monitored.
Oscillation voltage of
triangular wave
R
Start up signal
Internal signal which
cannot be externally
monitored.
PWM latch setting signal
internal signal which
cannot be externally
monitored.
Error amplifier input signal
V
Error amplifier output signal
V
I
OVP latch signal
Internal signal which
cannot be externally
monitored.
PWM output voltage
V
Note: 1. I
D *
IN
FB
COMP
OUT
T
Signal Name
/C
1
Pin 7
Pin 2
T
Pin 6
Pin 4
Pin 1
by power MOSFET current detection source resistance R
V
performed so that a voltage 1/3 that of V
D
COMP
indicates the power MOSFET drain current; it is actually observed as voltage V
HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP
indicates the error amp output voltage waveform.
Power ON
IC operates and
PWM output stops.
0V
0V
0V
0V
0V
0V
0V
0V
0V
0V
0V
2 V
IC turn ON
(8.4 V)
( ) shows the case
using HA17385H
16 V
V
4.7 V
IN
2.8 V
Stationary operation
1.2 V
5 V
COMP
Start up latch
release
This voltage is determined
by the transformer
Waveform timing (Outline)
is the current limiter level.
V
I
COMP
D
4.7 V
OVP input
S
.
7.0 V typ
(OVP input)
OVP latched
condition
Current mode operation is
Power OFF
(7.6 V)
10 V
S
generated
7.0 V
Reset of
OVP latch
2 V
11