MAX1565 Datasheet, PDF (10/26 Pages) Maxim Integrated Products – Small, High-Efficiency, Five-Channel Digital Still Camera Power Supply

Small, High-Efficiency, Five-Channel
Digital Still Camera Power Supply
Pin Description (continued)
PIN
NAME
FUNCTION
Step-Down Converter Feedback Input. For a 1.5V output, short FBSELSD to GND and connect FBSD to
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FBSD OUTSD. For other voltages, short FBSELSD to OUTSU and connect a resistive voltage-divider from OUTSD
to FBSD to GND. The FBSD feedback threshold is 1.25V. This pin is high impedance in shutdown.
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ON1 ^{Auxiliary Controller 1 On/Off Control Input. Drive ON1 high to turn on. This pin has an internal 330kΩ}
pulldown resistor. ON1 cannot start until OUTSU is in regulation.
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ON2 ^{Auxiliary Controller 2 On/Off Control Input. Drive ON2 high to turn on. This pin has an internal 330kΩ}
pulldown resistor. ON2 cannot start until OUTSU is in regulation.
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ON3 ^{Auxiliary Controller 3 On/Off Control Input. Drive ON3 high to turn on. This pin has an internal 330kΩ}
pulldown resistor. ON3 cannot start until OUTSU is in regulation.
Step-Up Converter On/Off Control. Drive ONSU high to turn on the step-up converter. All other control pins
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ONSU are locked out until 2ms after the step-up output has reached its final value. This pin has an internal 330kΩ
resistance to GND.
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REF
Reference Output. Bypass REF to GND with a 0.1µF or greater capacitor. The maximum allowed load on
REF is 200µA. REF is actively pulled to GND when all converters are shut down.
Step-Up Converter Feedback Input. To regulate OUTSU to 3.35V, connect FBSELSU to GND. FBSU may be
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FBSU
connected to OUTSU or GND. For other output voltages, connect FBSELSU to OUTSU and connect a
resistive voltage-divider from OUTSU to FBSU to GND. The FBSU feedback threshold is 1.25V. This pin is
high impedance in shutdown.
Step-Up Converter Compensation Node. Connect a series RC from COMPSU to GND to compensate the
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COMPSU control loop. COMPSD is pulled to GND in normal shutdown and during thermal shutdown (see the Step-
Down Compensation section).
Step-Up Feedback Select Pin. With FBSELSU = GND, OUTSU regulates to 3.35V. With FBSELSU = OUTSU,
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FBSELSU FBSU regulates to a 1.25V threshold for use with external feedback resistors. This pin is high impedance in
shutdown.
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FBSELSD ^{Step-Down Feedback Select Pin. With FBSELSD = GND, FBSD regulates to 1.5V. With FBSELSD = OUTSU,}
FBSD regulates to 1.25V for use with external feedback resistors. This pin is high impedance in shutdown.
Auxiliary Controller 1 Feedback Select Pin. With FBSEL1 = GND and FB1 regulates to 5V. With FBSEL1 =
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FBSEL1 OUTSU, FB1 regulates to 1.25V for use with external feedback resistors. This pin is high impedance in
shutdown.
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OSC ^{Oscillator Control. Connect a timing capacitor from OSC to GND and a timing resistor from OSC to OUTSU}
to set the oscillator frequency between 100kHz and 1MHz. This pin is high impedance in shutdown.
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PGNDB
Power Ground. Connect PGNDA and PGNDB together and to GND with short trace as close to the IC as
possible.
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LXSU ^{Step-Up Converter Power-Switching Node. Connect LXSU to the step-up converter inductor. LXSU is high}
impedance in shutdown.
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OUTSUA
Step-Up Converter Output. OUTSUA is the power output of the step-up converter. Connect OUTSUA to
OUTSUB at the IC.
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SDOK This open-drain output goes high impedance when the step-down has successfully completed soft-start.
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