7 Detailed Description

7.1 Overview

The TPSM8281x synchronous switch mode DC/DC converter power modules are based on a fixed-frequency

peak current-mode control topology. The control loop is internally compensated. To optimize the bandwidth of

the control loop to the wide range of output capacitance that can be used with the TPSM8281x, one of two

internal compensation settings can be selected. See COMP/FSET. The compensation setting is selected either

by a resistor from COMP/FSET to GND or by the logic state of this pin. The regulation network achieves fast and

stable operation with small external components and low-ESR ceramic output capacitors.

The device supports forced fixed frequency operation (FPWM) with the MODE/SYNC pin tied to a logic high

level. The frequency is defined as either 2.25 MHz (internally fixed when COMP/FSET is tied to GND or VIN)

or in a range of 1.8 MHz to 4 MHz (defined by a resistor from COMP/FSET to GND). Alternatively, the device

can be synchronized to an external clock signal in a range from 1.8 MHz to 4 MHz, applied to the MODE/SYNC

pin with no need for additional passive components. An internal PLL allows the device to change from internal

clock to external clock during operation. The synchronization to the external clock is done on the falling edge

of the clock applied at MODE/SYNC to the rising edge on the internal SW node. When the MODE/SYNC pin

is set to a logic low level, the device operates in power save mode (PSM). At low output current, the device

operates in PFM mode and automatically transitions to fixed-frequency PWM mode at higher output current. In

PFM operation, the switching frequency decreases linearly based on the load to sustain high efficiency down to

very low output current (see Power Save Mode Operation (PSM) for more details).

The TPSM8281xP versions in the VCA package utilize MagPack technology to deliver the highest-performance

power module design. Leveraging our proprietary integrated-magnetics packaging technology, MagPack

(magnetics in package) power modules deliver industry-leading power density, high efficiency and good thermal

performance, ease of use, and reduced EMI emissions.

7.2 Functional Block Diagram

+

-

GND

VIN

EN

Oscillator

Gate Drive and Control

Device

Control

PG

Thermal

shutdown

Bias

Regulator

gm

Ipeak

VREF

SS/TR

COMP/FSET

MODE/SYNC

Izero

–

–

L

FB

Output

Discharge

RDis

VOUT

SW

TPSM82816

SLUSEY7A – DECEMBER 2022 – REVISED JUNE 2024

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