412
Regulator ICs
4-channel switching regulator
controller
BA9737KV
The BA9737KV is a 4-channel controller that includes all of the circuits required to construct a switching regulator. The
circuits on the chip include a triangular-wave oscillator, a reference voltage circuit, an error amplifier, a PWM comparator,
a pseudo-totem-pole driver, and a short-circuit protection circuit.
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Applications
Camcoders and digital still cameras etc.
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Features
1) The totem-pole driver can directly drive power tran-
sistors, and the on current can be set to the rating cur-
rent using an external resistor.
For the off current, the peak current can be set using
an external capacitor.
2) Output cutoff circuit (timer latch type) for overload
protection.
3) Channels 2 and 3 are supplied using the internal ref-
erence voltage, and use a positive voltage only.
Channels 1 and 4 are general-purpose channels,
and all inputs are externally available.
4) Channels can be switched off individually or all to-
gether (STB and STB1 to STB4).
5) Dead-time control is provided for all channels, and
duty limits can be used.
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Absolute maximum ratings (Ta = 25
_
C)
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Recommended operating conditions (Ta = 25
_
C)
415
Regulator ICs
BA9737KV
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Electrical characteristics (unless otherwise noted, Ta = 25
_
C, V
CC
= 6.0V, fosc = 0.45MHz, STB,
STB1 to STB4 = 5V)
416
Regulator ICs
BA9737KV
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Operation notes
(1)
Use short and wide wiring tracks for the power sup-
ply and ground to keep the mutual impedance as small
as possible, and use inductors and capacitors to keep
ripple to a minimum.
(2)
Great care has been paid to the quality of this com-
ponent. However, if the absolute maximum ratings for
temperature and applied voltage are exceeded, the IC
may be destroyed.
Since it is not possible to predict whether it will be in short
mode or open mode if the IC is destroyed, if there is a
chance that the maximum ratings of the IC will be ex-
ceeded, use appropriate physical protective measures
(fuses etc.).
(3)
Set the dead-time input voltage to 0.58V or more.
(4)
This IC does not use an internal circuit to generate
the output on peak current, so we recommend that you
connect capacitors to each end of R
BIAS
to externally gen-
erate the on peak current (after taking power dissipation
and efficiency into consideration). In this case, there is a
possibility that the output waveform may become unsta-
ble due to the current impedance, so we recommend that
you connect resistors (of about 100
to 500
) in series
with the off peak capacitors.
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External dimensions (Units: mm)
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