LT8625SP datasheet(9/44 Pages) AD

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Data Sheet

LT83401/LT83402

analog.com

Rev. 0

9 of 44

PIN CONFIGURATIONS AND FUNCTIONAL DESCRIPTIONS

Figure 3. Pin Configurations

Table 3. Pin Descriptions

NAME

DESCRIPTION

A resistor is connected between the RT and ground to set the switching frequency.

The PG pin is the open-drain output of an internal comparator. PG remains high

impedance until the PGFB pin is within ±7.5% of 0.5V, and there are no fault

conditions. PG is pulled low when EN/UVLO is below 0.75V, INTVCC has fallen too low,

or during thermal shutdown. PG is valid when VIN is above 2.8V.

SYNC/MODE

For the LT83401/LT83402, this pin programs three different operating modes: 1) Pulse-

Skipping Mode: Connect this pin to GND for pulse-skipping mode for improved

efficiency at light loads. 2) Forced Continuous Mode (FCM): This mode offers fast

transient response and full frequency operation over a wide load range. Connect this

pin high to INTVCC (~3.4V) or an external supply greater than 1.5V for FCM. The part also

operates in this mode by default if this pin is left floating. 3) Synchronization Mode:

Drive this pin with a clock source to synchronize to an external frequency. During

synchronization, the part operates in forced continuous mode. The SYNC/MODE pin

can be toggled during operation to change the operating mode. Contact the factory for

versions of this part that replace the SYNC/MODE pin with a CLKOUT pin. The CLKOUT

pin would provide a 50% duty-cycle square wave of the switching frequency, 180° out-

of-phase with the internal clock of the part, with a peak-to-peak amplitude of INTVCC to

GND.

LFCSP PACKAGE

15-LEAD (3mm × 2mm × 0.75mm)

JEDEC BOARD θJA = 50°C/W, θJC(TOP) = 67.1°C/W, θJC(PAD) = 10.4°C/W

DEMO BOARD θJA = 33°C/W, ψJT = 1.7°C/W

EXPOSED PAD IS GND AND SHOULD BE SOLDERED TO PCB

SYNC/MODE

VIN

BST

10 INTVCC

11 EN/UVLO

LT83401/LT83402

TOP VIEW

16 GND

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