The LM5157x device is a wide input range, non-synchronous boost converter that uses peak-current-mode control. The device can be used in boost, SEPIC, and flyback topologies.

The device can start up from a single-cell battery with a minimum of 2.9 V. It can operate with input supply voltage as low as 1.5 V if the BIAS pin is greater than 2.9 V. The internal VCC regulator also supports BIAS pin operation up to 45 V (50-V absolute maximum). 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 response. To reduce the EMI of the power supply, the device provides an optional dual random spread spectrum, which reduces the EMI over a wide frequency span.

The device features an accurate current limit over the input voltage range. Low operating current and pulse skipping operation improve efficiency at light loads.

The device also has built-in protection features such as overvoltage protection, line UVLO, and thermal shutdown. Selectable Hiccup mode overload protection protects the converter during prolonged current limit conditions. Additional features include the following:

• Low shutdown I_Q
• Programmable soft start
• Precision reference
• Power good indicator
• External clock synchronization