7.1 Overview

The TPS61087-Q1 boost converter is designed for output voltages up to 18.5 V with a switch peak current limit of 3.2-A minimum. The device, which operates in a current mode scheme with quasi-constant frequency, is externally compensated for maximum flexibility and stability. The switching frequency is selectable from 650 kHz to 1.2 MHz and the minimum input voltage is 2.5 V. To limit the inrush current at start-up, a soft-start pin is available.

The novel topology of the TPS61087-Q1 boost converter using adaptive OFF-time provides superior load and line transient responses and operates also over a wider range of applications than conventional converters.

The selectable switching frequency offers the possibility to optimize the design either for the use of small sized components (1.2 MHz) or for higher system efficiency (650 kHz). However, the frequency changes slightly because the voltage drop across the r_DS(on) has some influence on the current and voltage measurement and thus on the ON-time (the OFF-time remains constant).

Depending on the load current, the converter operates in continuous conduction mode (CCM), discontinuous conduction mode (DCM), or pulse skip mode to maintain the output voltage.