An adaptation of the BLF SRK FET v2 by RMM, which evolved from the original BLF SRK FET driver by Mattaus, Comfychair, WarHawk-AVG and many others.
First version, introduced in this post.
Triple Channel and LFPAK56
Narsil support, became outdated quickly after DEL’s testing of FET drivers
Support for ATtiny 25/45/85 (Narsil) and DEL’s R5
This version kept most features of the BLF SRK FET v2,
as well as several redundant component places for testing purposes
Updated version featuring
- Triple Channel with 11x AMC7135
- LFPAK56 MOSFET
- Supporting 13A and 25/45/85 (Narsil)
- R5 for ringing protection
- Indicator LED at MCU pin#3 or pin#7
- Dedicated bleeder resistor from Bat+ to GND
- Wider path from GND to FET source
Optimized for High Current
First notable change is the use of an
- LFPAK56 MOSFET
Then there are
- 9 additional AMC7135 (Q2-10) for a high mode without PWM
And you can use
- Pin3 as third channel and connect either the FET or Q2-10 to it
Pin5 is hardwired to the single 7135 (Q1) for the low modes.
Pin6 and Pin3 can (using a fancy 4-pad-connector) alternatively be connected to Q2-10 or the FET. Use Pin6 for the channel you want to PWM, be it the FET or Q2-10. Use Pin3 for the channel you want to just switch On/Off.
You can still use it as a dual channel SRK FET driver with LFPAK56: Connect Pin6 to FET using a zero-Ohm-resistor and you have all the functions of the v2 driver but can use the NXP MOSFETs.
But the additional 7135s are where the fun begins:
The OTC was just for testing.
This particular driver has the FET connected to Pin3 and Q2-10 to Pin6. It has 6 modes:
Off – [0mA] – (Pin5, Pin6 and Pin3 OFF)
Moon – [~1mA] – (PWM-2 on Pin5, Pin6 and Pin3 OFF)
Low – [35mA] – (PWM-34 on Pin5, Pin6 and Pin3 OFF)
Medium – [350mA] – (Pin5 ON, Pin6 and Pin3 OFF)
High – [3500mA] – (Pin5 and Pin6 ON, Pin3 OFF)
Turbo – [All-In] – (Pin3 ON, Pin5 and Pin6 OFF)
Moon and Low use PWM at 19kHz (9.6MHz, Fuse7A, PhaseCorrectPWM, Divider1).
Medium switches Q1, High switches Q1 and Q2-10, Turbo switches the FET.
I could now PWM Q2-10, but I don’t need to: the mode spacing of 35-350-3500 is still my favourite.
Oshpark links, eagle pics and changelog later. This driver lies on my workbench and begs for attention…
A closer look to the main section