LT8253/LT8253A

5

Rev. 0

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PIN FUNCTIONS

TG1: Buck Side Top Gate Drive. Drives the gate of buck

side top N-Channel MOSFET with a voltage swing from

SW1 to BST1.

LSP: Positive Terminal of the Buck Side Inductor Current

Sense Resistor. Ensure accurate current sense with Kelvin

connection.

LSN: Negative Terminal of the Buck Side Inductor Current

Sense Resistor. Ensure accurate current sense with Kelvin

connection.

input to determine its operation regions. Locally bypass

this pin to ground with a minimum 0.1μF ceramic

capacitor.

ers the internal control circuitry and gate drivers. Locally

bypass this pin to ground with a minimum 4.7µF ceramic

capacitor.

EN/UVLO: Enable and Undervoltage Lockout. Force the

pin below 0.3V to shut down the part and force the pin

above 1.23V for normal operation. The 1.22V falling

threshold and 2.5μA pull-down current can be used to

TEST: Factory Test. This pin is for factory testing purpose

only and must be directly connected to ground for proper

operation.

VOUTEN: Output Enable. The VOUTEN pin is used to

enable buck-boost switching and deliver output power.

accurate 2V reference capable of supplying 1mA current.

Locally bypass this pin to ground with a 0.47μF ceramic

capacitor.

PGOOD: Power Good Open Drain Output. The PGOOD pin

is pulled low when the FB pin is within ±10% of its regu-

lation voltage. To function, the pin requires an external

pull-up resistor.

SS: Soft-Start Timer Setting. The SS pin is used to set

soft-start timer by connecting a capacitor to ground. An

internal 12.5μA pull-up current charging the external SS

capacitor gradually ramps up FB regulation voltage.

FB: Voltage Loop Feedback Input. The FB pin is used for

output voltage regulation and output fault protection.

VC: Error Amplifier Output. The VC pin is used to com-

pensate the control loop with an external RC network.

RT: Switching Frequency Setting. Connect a resistor from

this pin to ground to set the internal oscillator frequency.

SYNC/SPRD: External Clock Frequency Synchronization

or Spread Spectrum. Ground this pin for switching at

internal oscillator frequency. Apply a clock signal for

spread spectrum frequency modulation.

power output to determine its operation regions. Locally

bypass this pin to ground with a minimum 0.1μF ceramic

capacitor.

TG2: Boost Side Top Gate Drive. Drives the gate of boost

side top N-Channel MOSFET with a voltage swing from

SW2 to BST2.

SW2: Boost Side Switch Node.

BST2: Boost Side Bootstrap Floating Driver Supply. The

BST2 pin has an integrated bootstrap diode from the

to the SW2 pin.

BG2: Boost Side Bottom Gate Drive. Drives the gate of

boost side bottom N-Channel MOSFET with a voltage

BG1: Buck Side Bottom Gate Drive. Drives the gate of

buck side bottom N-Channel MOSFET with a voltage

BST1: Buck Side Bootstrap Floating Driver Supply. The

BST1 pin has an integrated bootstrap diode from the

to the SW1 pin.

SW1: Buck Side Switch Node.

GND (Exposed Pad): Ground. Solder the exposed pad

directly to the ground plane.