MAX26239/MAX26240

4.5V to 36V, 6A Buck-Boost Converters

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Analog Devices | 11

Synchronization Input (SYNC)

The SYNC pin is a logic-level input used for operating mode selection and frequency control. Connecting SYNC to VCC

or to an external clock enables forced fixed-frequency (FPWM) operation. Connecting SYNC to GND enables automatic

skip-mode operation for better light load efficiency. The external clock frequency at SYNC can be higher or lower than

the internal clock by 20%. The devices synchronize to the external clock in two cycles. When the external clock signal at

SYNC is absent for more than two clock cycles, the devices use the internal clock.

System Enable (EN)

An enable control input (EN) activates the devices from their low-power shutdown mode. EN is compatible with inputs

from VIN down to 1.8V. EN turns on the internal linear (VCC) regulator. Once VCC is above the internal lockout threshold

(VUVLO_VCC = 1.7V, typ), the converter activates and the output voltage ramps up with the programmed soft-start time.

A logic-low at EN shuts down the device. During shutdown, the VCC regulator and gate drivers turn off. Shutdown is the

lowest power state and reduces the quiescent current to 5μA (typ). Drive EN high to bring the device out of shutdown.

Spread-Spectrum Option (SPS)

When the SPS pin is tied high, the operating frequency is varied ±6% centered on the switching frequency.

The internal spread spectrum is disabled if the devices are synchronized to an external clock. However, the devices do

not filter the external clock on the SYNC pin and pass any modulation (including spread spectrum) present driving the

external clock.

Thermal Shutdown Protection

Thermal shutdown protects the device from excessive operating temperature. When the junction temperature exceeds

+175°C, the sensor shuts down the converter, allowing the IC to cool. The sensor turns the IC on again after the junction

temperature cools by 20°C. Thermal shutdown only disables the power switching; the VCC regulator and IC logic remain

active during thermal shutdown.