The soft start function enabled by connecting an external capacitor between the NRCS pin and GND. Output ramp-up
can be set for any period up to the time the NRCS pin reaches V
FB
(0.65V). During startup, the NRCS pin serves as a
20µA (TYP) constant current source to charge the external capacitor. Output start time is calculated by the formula
below.
t
NRCS
typ
½
7.
C
NRCS
V
FB
I
NRCS
TSD (Thermal Shut down)
The shutdown (TSD) circuit is automatically latched OFF when the chip temperature exceeds the threshold
temperature after the programmed time period elapses, thus protecting the IC against “thermal runaway” and heat
damage. Since the TSD circuit is designed only to shut down the IC in the occurrence of extreme heat, it is important
that the Tj (max) parameter should not be exceeded in the thermal design, in order to avoid potential problems with the
TSD.
t
TSD
typ
½
8.
C
SCP
V
SCPTH
20
A
IN
The IN line acts as the major current supply line, and is connected to the output N-Channel FET drain. Since there is
no electrical connection (such as between the VCC pin and the ESD protection diode) required, IN operates
independent of the input sequence. However, since an output N-Channel FET body diode exists between IN and OUT,
a V
IN
-V
OUT
electric (diode) connection is present. Therefore, when output is switched ON or OFF, reverse current may
flow from OUT to IN.
SCP
When output voltage (OUT) drops, the IC assumes that OUT pin is shorted to GND and switches the output voltage
OFF. After the GND short has been detected and the programmed delay time has elapsed, the output is latched OFF.
SCP is also effective during output startup. SCP condition can be cleared either by reconnecting the EN pin or VCC pin.
Delay time is calculated by the formula below.
9.
t
SCP
typ
½
C
SCP
V
SCPTH
I
SCP
Absolute Maximum Ratings
（Ta=25°C）
Parameter
Input Voltage 1
Input Voltage 2
Maximum Output Current
Enable Input Voltage
Power Dissipation 1
Power Dissipation 2
Power Dissipation 3
Power Dissipation 4
Operating Temperature Range
Storage Temperature Range
Maximum Junction Temperature
Symbol
V
CC
V
IN
I
OUT
V
EN
Pd1
Pd2
Pd3
Pd4
Topr
Tstg
Tjmax
Limit
6.0
(Note 1)
6.0
(Note 1)
4
(Note 1)
6.0
1.00
(Note 2)
1.45
(Note 3)
2.31
(Note 4)
3.20
(Note 5)
-10 to +100
-55 to +125
+150
Unit
V
V
A
V
W
W
W
W
°C
°C
°C
(Note 1) Should not exceed Pd.
(Note 2) Derate by 8mW/°C for Ta above 25°C (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, no copper foil area)
(Note 3) Derate by 11.6mW/°C for Ta above 25°C (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, 2-layer, copper foil area : 15mm x 15mm)
(Note 4) Derate by 18.5mW/°C for Ta above 25°C (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, 2-layer,copper foil area : 70mm x 70mm)
(Note 5) Derate by 25.6mW/°C Ta above 25°C (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, 4-layer, copper foil area : 70mm x 70mm)
Caution:
Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between pins or an open circuit
between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the IC is operated over
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