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.
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 IN-OUT electric (diode) connection is present. Therefore, when output is switched ON or OFF, reverse current may
flow from IN to OUT.
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.
8.
9.
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
Operating Temperature Range
Storage Temperature Range
Maximum Junction Temperature
Symbol
V
CC
V
IN
I
OUT
V
EN
Pd1
Pd2
Pd3
Topr
Tstg
Tjmax
Limit
+6.0
(Note 1)
+6.0
(Note 1)
2
(Note 1)
-0.3 to +6.0
0.63
(Note 2)
1.35
(Note 3)
1.75
(Note 4)
-10 to +100
-55 to +125
+150
Unit
V
V
A
V
W
W
W
°C
°C
°C
(Note 1) Should not exceed Pd.
(Note 2) Derate by 5.04mW/°C Ta above 25°C (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, 1-layer,
copper foil area : less than 0.2%)
(Note 3) Derate by 10.8mW/°C Ta above 25°C (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, 1-layer,
copper foil area : less than 7.0%)
(Note 4) Derate d by 14.0mW/°C Ta above 25°C (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, 1-layer,
copper foil area : less than 65.0%)
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
the absolute maximum ratings.
Recommended Operating Conditions
(Ta=25°C)
Parameter
Input Voltage 1
Input Voltage 2
Output Voltage Setting Range
Enable Input Voltage
NRCS Capacity
Symbol
V
CC
V
IN
V
OUT
V
EN
C
NRCS
-0.3
0.001
BD35230HFN
Min
4.3
1.3
1.0 (fixed)
+5.5
1
-0.3
0.001
Max
5.5
V
CC
-1
(Note 5)
BD35231HFN
Min
4.3
1.5
1.2 (fixed)
+5.5
1
Max
5.5
V
CC
-1
(Note 5)
Unit
V
V
V
V
µF
(Note 5) VCC and IN do not have to be implemented in the order listed.
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