LTM8022 datasheet(6/20 Pages) LINER

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LTM8022

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PIN FUNCTIONS

VIN (Bank 1): The VIN pin supplies current to the LTM8022’s

internal regulator and to the internal power switch. This

pin must be locally bypassed with an external, low ESR

capacitor of at least 2.2μF.

VOUT (Bank 2): Power Output Pins. Apply the output ﬁlter

capacitor and the output load between these pins and

GND pins.

AUX (Pin F5): Low current voltage source for BIAS. In

many designs, the BIAS pin is simply connected to VOUT.

The AUX pin is internally connected to VOUT and is placed

adjacent to the BIAS pin to ease printed circuit board rout-

ing. Although this pin is internally connected to VOUT, do

NOT connect this pin to the load. If this pin is not tied to

BIAS, leave it ﬂoating. The Application Information sec-

tion gives speciﬁc information about the BIAS and AUX

connections

BIAS (Pin G5): The BIAS pin connects to the internal power

bus. Connect to a power source greater than 2.4V. If the

output is greater than 2.4V, connect this pin there. If the

output voltage is less, connect this to a voltage source

between 2.4V and 30V. Also, make sure that BIAS + VIN

is less than 56V.

RUN/SS (Pin H5): Tie RUN/SS pin to ground to shut down

the LTM8022. Tie to 2.5V or more for normal operation.

If the shutdown feature is not used, tie this pin to the VIN

pin. RUN/SS also provides a soft-start function; see the

Applications Information section.

GND (Bank 3): Tie these GND pins to a local ground plane

below the LTM8022 and the circuit components. Return

the feedback divider (RADJ) to this pin.

RT (Pin G7): The RT pin is used to program the switching

frequency of the LTM8022 by connecting a resistor from

this pin to ground. The Applications Information section of

the data sheet includes a table to determine the resistance

value based on the desired switching frequency. Minimize

capacitance at this pin.

SHARE (Pin F7): Tie this to the SHARE pin of another

LTM8022 when paralleling the outputs. Otherwise, leave

this pin ﬂoating.

SYNC (Pin G6): External Clock Synchronization Input.

Ground this pin for low ripple Burst Mode® operation at

low output loads, or connect to a stable voltage source

above 0.7V to disable Burst Mode operation. Do not leave

this pin ﬂoating. Tie to a clock source for synchronization.

Clock edges should have rise and fall times faster than

1μs. See Synchronization in the Applications Information

section.

PG (Pin H6): Open Collector Output of an Internal Com-

parator. PG remains low until the ADJ pin is within 10%

of the ﬁnal regulation voltage. PG output is valid when VIN

is above 3.6V and RUN/SS is high. If this function is not

used, leave this pin ﬂoating.

ADJ (Pin H7): The LTM8022 regulates its ADJ pin to 0.79V.

Connect the adjust resistor from this pin to ground. The

value of RADJ is given by the equation, RADJ = 394.21/(VOUT

– 0.79), where RADJ is in kΩ.

Burst Mode is a registered trademark of Linear Technology Corporation.

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