SI-8050JD
Step-Down
to 5.0 V, 1.5 A,
DC/DC Converter
APPLICATIONS INFORMATION
Input Capacitor (C1). Capacitors with low impedance
for high-frequency ripple current must be used.
Soft-Start Capacitor (C3). Soft start for the converter
is enabled by connecting a capacitor between terminal 5
and ground. The converter may be turned off by decreasing
the terminal 5 voltage below 0.5 V with either an npn
small-signal transistor or the output of open-collector TTL.
If both a large soft-start capacitor and on/off control are
desired, collector current limiting must be used to prevent
transistor damage. No external voltage can be applied to
terminal 5.
Output Capacitor (C2). Capacitors with low impedance
for high-frequency ripple current must be used. Especially
when the C2 impedance is high, the switching waveform
may not be normal at low temperatures. Film or tantalum
capacitor for C2 may cause abnormal oscillations.
Catch Diode (D1). Diode D1 must be a Schottky diode.
Other diode types will result in increased forward voltage
spikes, reverse current flow, increased IC power dissipa-
tion during the off period, and possible destruction of the
IC.
Choke Coil (L1). If the winding resistance of the choke
coil is too high, the circuit efficiency will decrease. As the
overcurrent protection start current is approximately 2.5 A,
attention must be paid to the heating of the coil by magnetic
saturation due to overload. To reduce the output ripple, the
inductor may be increased at the expense of excessive
board area and cost.
Parallel Operation. Parallel operation to increase load
current is not permitted.
Overcurrent Protection. The SI-8000JD series has a
built-in fold-back type overcurrent protection circuit, which
limits the output current at a start-up mode. It thus cannot
be used in applications that require current at the start-up
mode such as:
(1) constant-current load,
(2) power supply with positive and negative outputs to
common load (a center-tap type power supply), or
(3) raising the output voltage by putting a diode or a
resistor between the device ground and system ground.
SI-8050JD
Typical Application
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