AnsweredAssumed Answered

LTC4013 won't charge

Question asked by billnorton on Jun 1, 2018
Latest reply on Jun 5, 2018 by Zack

Li-ion charger modeled after schematic on datasheet page 35. 

Design specs 

DCIN 22 - 24V

Vbat 12.3V

Max charge current 20A.

 

How it works

With the battery at 6.3V, DCIN = 24V/3A from bench supply, Green LED comes on

INTVcc = 5.01V

FB = 1.42V

Enab = 1.49V

LB = 1.22V

SW:

Scope says it's 917kHz, with 232K on RT. (in-circuit with power off and caps drained it measures 146K.)

TG:

BG:

A DVM with a current shunt says there's no charging current.

The bench supply says it's supplying .011A

(With DCIN turned off, and an auto headlamp on the battery, the DVM says it draws 6.6A, so it can measure current.)

 

What do I need to look at to get it charging?

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