7.1 Overview

The TPS61391 is a fully integrated boost converter with an 85-V FET to convert a low input voltage to a higher voltage for biasing the APD. The TPS61391 supports an input voltage ranging from 2.5 V to 5.5 V. The device operates at a 700 kHz pulse-width modulation (PWM) crossing the whole load range.

There are two ratio options for the current proportional to APD current: the MON1 (4 : 5) and MON2 (1 : 5). By connecting a resistor from the mirror output (MON1 or MON2) to GND, the current flowing through the APD is converted into the voltage crossing the resistor from MON1 / MON2 to GND.

Additionally, a high power optical protection is integrated by clamping the pre-set current limit (program by the I_SHORT resistor). The response time of the high optical power is typically 0.5 µs. The device could recovery automatically when the high optical power is removed.

The device comes in a 3-mm × 3-mm QFN package with the operating junction temperature covering from –40°C to 125°C.