1 Features

• AEC-Q100 qualified for automotive applications

– Temperature grade 1: –40°C to +125°C, TA

• Functional Safety-Capable

– Documentation available to aid functional safety

system design

• Suited for wide operating range automotive battery

powered applications

– 3.8-V to 42-V input operating range

– Dynamically programmable VOUT from 5 V to

20 V, or from 15 V to 57 V

– Minimum boost input 0.8 V when BIAS ≥ 3.8 V

– Bypass operation when VSUPPLY > VLOAD

• BIAS shutdown current ≤ 3 μA

• Small solution size

– Maximum switching frequency 2.2 MHz

– Internal boot diode

– QFN-20 with wettable flanks

• EMI mitigation and avoid AM band interference

and crosstalk

– Optional clock synchronization

– Switching frequency from 100 kHz to 2.2 MHz

– Selectable switching mode (FPWM, diode

emulation)

– Optional programmable spread spectrum

– Lead-less package

• Programmability and flexibility

– Dynamic VOUT tracking

– Dynamic switching frequency programming

– Supports DCR inductor current sensing

– Programmable input voltage UVLO

– Adjustable soft start

– Adaptive dead-time

– PGOOD indicator

• Integrated protection features

– Constant cycle-by-cycle peak current limit over

VSUPPLY

– Overvoltage protection

– HB-SW short protection

– Thermal shutdown

2 Applications

• Automotive audio power supply with tracking

• Automotive LED bias supply

3 Description

The LM51231-Q1 device is a wide input range

synchronous boost controller that employs peak

current mode control. The device's wide input range

supports automotive cold-crank and load dump. The

minimum input voltage can be as low as 0.8 V

when BIAS is equal to or greater than 3.8 V. The

output voltage can be dynamically programmed by

using the tracking function. Bypass mode operation

is automatically entered when VSUPPLY > VLOAD,

eliminating the body diode drop of the high-side

MOSFET. The switching frequency is dynamically

programmed with an external resistor from 100 kHz

to 2.2 MHz. Switching at 2.2 MHz minimizes AM band

interference and allows a small solution size and fast

transient response.

The device has built-in protection features such as

peak current limit, which is constant over VSUPPLY,

overvoltage protection, and thermal shutdown.

External clock synchronization, programmable spread

spectrum modulation, and a lead-less package with

minimal parasitic, help to reduce EMI and avoid cross

talk. Additional features include line UVLO, FPWM,

diode emulation, DCR inductor current sensing,

programmable soft start, and a power-good indicator