The LM5155x-Q1 ( LM5155-Q1 and LM51551-Q1 ) device is a wide input range,
non-synchronous boost controller that uses peak current mode control. The device can be used in
boost, SEPIC, and flyback topologies.
The LM5155x-Q1 device can start up from a 1-cell battery with a minimum
of 2.97 V if the BIAS pin is connected to the VCC pin. It can operate with the input supply voltage
as low as 1.5 V if the BIAS pin is greater than 3.5 V.
The internal VCC regulator also supports BIAS pin operation up to 45 V (50-V absolute
maximum) for automotive load dump. The switching frequency
is dynamically programmable with an external resistor from 100 kHz to 2.2 MHz. Switching at 2.2 MHz
minimizes AM band interference and allows for a small solution size and fast transient
The device features a 1.5-A standard MOSFET driver and a low 100-mV current limit
threshold. The device also supports the use of an external VCC supply to improve efficiency. Low
operating current and pulse-skipping operation improve efficiency at light loads.
The device has built-in protection features such as cycle-by-cycle current limit,
overvoltage protection, line UVLO, and thermal shutdown. Hiccup mode overload protection is
available in the LM51551-Q1 device option. Additional features include low shutdown
IQ, programmable soft start, programmable slope compensation, precision
reference, power-good indicator, and external clock synchronization.