My lats are arguably my strongest part, but they weren't always:
Here's my exact routine (plus weights, so you can get an idea of warm-ups and % of max that I'm doing):
Hanging leg Raises from the pull-up bar:
2 sets of 8
Weighted pull-ups:
(bw + 45) x 6
(bw + 65) x 6
(bw + 70) x 3
(bw + 90) x 3
bent-over DB rows:
100 x 6
105 x 6
bent-over BB rows:
155 x 8
Done.
I do some bicep work at the end, but you're asking about back.