LTC3589_1 Datasheet, PDF (13/46 Pages) Linear Technology – 8-Output Regulator with Sequencing and I2C

LTC3589
PIN FUNCTIONS
V_{IN_LDO2} (Pin 1): Power Input for LDO2. This pin should
be bypassed to ground with a 1µF or greater ceramic
capacitor.
LDO2 (Pin 2): Output Voltage of LDO2. Nominal output
voltage is set with a resistor feedback divider that servos
to an I²C register controlled DAC reference. This pin must
be bypassed to ground with a 1µF or greater ceramic
capacitor.
LDO3 (Pin 3): Output Voltage of LDO3. Nominal output
voltage is fixed at 1.8V. This pin must be bypassed to
ground with a 1µF or greater ceramic capacitor.
LDO4 (Pin 4): Output Voltage of LDO4. Output voltages
of 1.8V, 2.5V, 2.8V, and 3.3V are selected via the I²C port.
This pin must be bypassed to ground with a 1µF or greater
ceramic capacitor.
V_{IN_LDO34} (Pin 5): Power Input for LDO3 and LDO4. This
pin should be bypassed to ground with a 1µF or greater
ceramic capacitor.
PV_IN1 (Pin 6): Power Input for Step-Down Switching
Regulator 1. Tie this pin to V_IN supply. This pin should
be bypassed to ground with a 4.7µF or greater ceramic
capacitor.
SW1 (Pin 7): Switch Pin for Step-Down Switching
Regulator 1. Connect one side of step-down switching
regulator 1 inductor to this pin.
RSTO (Pin 8): Reset Output. Open-drain output pulls low
when the always-on regulator LDO1 is below regulation
and during a hard reset initiated by a pushbutton input.
EN_LDO2 (Pin 9): Enable LDO2 Logic Input. Active high
input to enable LDO2. A weak pull-down forces EN_LDO2
low when left floating.
EN1 (Pin 10): Enable Step-Down Switching Regulator 1.
Active high input to enable step-down switching
regulator 1. A weak pull-down forces EN1 low when left
floating.
EN2 (Pin 11): Enable Step-Down Switching Regulator 2.
Active high input to enable step-down switching
regulator 2. A weak pull-down forces EN2 low when left
floating.
SW4AB (Pin 12): Switch Pin for Buck-Boost Switching
Regulator 4. Connected to the buck-boost internal power
switches A and B. Connect an inductor between this pin
and SW4CD (Pin 19).
EN3 (Pin 13): Enable Step-Down Switching Regulator 3.
Active high input to enable step-down switching
regulator 3. A weak pull-down forces EN3 low when left
floating.
EN4 (Pin 14): Enable Buck-Boost Switching Regulator 4.
Active high input to enable buck-boost switching
regulator 4. A weak pull-down forces EN4 low when left
floating.
PV_IN4 (Pin 15): Power Input for Switching Regulator 4.
Tie this pin to V_IN supply. This pin should be bypassed to
ground with a 4.7µF or greater ceramic capacitor.
BB_OUT (Pin 16): Output Voltage of Buck-Boost Switching
Regulator 4. This pin must be bypassed to ground with a
22µF or greater ceramic capacitor.
IRQ (Pin 17): Interrupt Request Output. Open-drain
driver is pulled low for power good, undervoltage, and
overtemperature warning and fault conditions. Clear IRQ
by writing to the I²C CLIRQ command register.
EN_LDO34 (Pin 18): Enable LDO3 and LDO4 Logic Input.
Active high to enable LDO3 and LDO4. Disable LDO4 via
I²C software commands using I²C command registers
OVEN or L2DTV2. A weak pull-down forces EN_LDO34
low when left floating.
SW4CD (Pin 19): Switch Pin for Buck-Boost Switching
Regulator 4. Connected to the buck-boost internal power
switches C and D. Connect an inductor between this node
and SW4AB (Pin 12).
PWR_ON (Pin 20): External Power-On. Handshaking pin
to acknowledge successful power-on sequence. PWR_ON
must be driven high within five seconds of WAKE going
high to keep power on. It can be used to activate the WAKE
output by driving high. Drive low to shut down WAKE.
ON (Pin 21): Pushbutton Input. A weak internal pull-up
forces ON high when left floating. A normally open push-
button is connected from ON to ground to force a low
state on this pin.
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