***Question*** *Anything wrong with connecting L298Ns in parallel?* --- ***Update 2021mar30hkt1601*** Preliminary testing shows that when two full H-bradges are paralleled to drive one motor: 1. The motor load current is shared between the two channels as 52% : 48% 2. The total load current is increased by 10%. In other words overall effeciency is 90% ***Conclusion: It is a good idea to parallel two bridges for a bigger current*** See Part 7 below for more details. --- **Answer** *Nothing wrong. Hobbyists do it. Engineers can also do it. It all depends on cost/benefit/risk hobbyist/engineer trade offs.* Let me explain, starting with ULN2803, then L298N. *Part 1 - ULN2803A Case* [ULN2803A Darlington Transistor Arrays - TI][1] From datasheet - Section 3 Description The ULN2803A device is a 50V, 500 mA Darlington transistor array. The device consists of eight NPN Darlington pairs that feature high-voltage outputs with common-cathode clamp diodes for switching inductive loads. The collector-current rating of each Darlington pair is 500 mA. ***The Darlington pairs may be connected in parallel for higher current capability.*** --- *Part 2 - L298N Case* [L298N Datasheet - ST][2] By the same ULN2803 token, L298N can also parallel output for bigger current. Since the BJTs to be paralleled are fabricated from the same die/chip, they should very nicely selfie balancing out the load current. --- [![l298n 1][3]][3] --- [![l298n 2][4]][4] --- *Part 3 - L298N Dual Full Bride DC Motor Driver Module Case* [AliExpress L298N Dual Full H Bridge DC Motor Driver Module - US$1][5] The very popular cheapy L298N motor driver modules are for driving two 4A (update: 2A each bridge) DC motors. For a bigger motor, say 8A (update: 4A), we can parallel two drivers into one big driver. Warning: me just friendly hobbyist. No guarantee no nothing would melt down or blow up. --- *Part 4 - Discussion and Recommendation* L298N output paralleling for bigger output current is a good newbie workaround. For ninjas, I would recommend forgetting the little old guy L298N, and go instead for the 40A big guy ***BTN7971B***. For more details on BTN7971B, see Refs 11.4, 11.5, and 11.6 of my answer to the following motor driver Q&A. [DC Motor Driver Q&A - EESE][6] --- ***Part 5 - Proof of Concept*** To prove my guess is correct, I am using a L298N module with the two channels' output paralleled, and measure the two channels's current when driving one DC motor. Below is the test procedure. 1. Setup a L298N module to drive two 12V DC motors, to make sure both H-Bridges are working correctly. 2. Remove one of the motor, and parallel both channel's outputs to drive the remaining one motor. 3. Use two multi-meters to measure each H-Bridge's output current, to see if they are balanced or not. --- [![l298n test][7]][7] --- YouTube Video - [L298N Module Driving Two DC Motors][8] --- *Part 6 - How to measure each of the two H-bridge output current to DC motor?* L298N has two current sense pins to measure the output current, using a current sense resistor, shown in pink/green/blue in the schematic below below (Also shown as ***Sense A, Rsa, and Sense B, Rsb*** in the last diagram of Part 2 above.). --- [![l298n current sense][9]][9] --- Part 7 - How to do the L298N current sensing wiring? Most of the cheapy L298N modules do not have current sensing resistor sockets and jummpers. So we need to do some DIY wiring. Let us first look at the current sense pins to fiddle, as shown below. --- [![current sense][10]][10] --- *Part 8 - Preliminary Test Results of two channels (full H-bridges) in parallel to drive only one motor* --- [![enter image description here][11]][11] --- Step 1 - Channel 1 only Channel 1 output to Motor 1 = 90mA Channel 2 output Not connected = 0.7mA Step 2 - Channel 1 and Channel 2 paralleled Channel 1 output to Motor 1 = 52mA Channel 2 output to Motor 1 = 48mA Total motor current = 52mA + 48mA = 100mA Channel 1 load = ***52%*** Channel 2 load current = ***48%*** ***Conclusion = nicely balanced*** --- */ to continue, ...* [1]: https://www.ti.com/lit/ds/symlink/uln2803a.pdf?ts=1616825443744&ref_url=https%253A%252F%252Fwww.google.com%252F [2]: https://www.st.com/resource/en/datasheet/l298.pdf [3]: https://i.sstatic.net/3XMSr.jpg [4]: https://i.sstatic.net/wRe9r.jpg [5]: https://fr.aliexpress.com/item/4001175036525.html?spm=a2g0o.search0302.0.0.5ab31cc6QSHakX&algo_pvid=f71aa4cb-f623-4a20-b2ef-553c0ca9a2c1&algo_expid=f71aa4cb-f623-4a20-b2ef-553c0ca9a2c1-25&btsid=0b0a555416168995427627943e6913&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ [6]: https://electronics.stackexchange.com/questions/510755/help-with-choice-of-dc-motor-speed-control-pwm-vs-regulator/510834#510834 [7]: https://i.sstatic.net/7TbJA.jpg [8]: https://youtu.be/N_S0UhgZozE [9]: https://i.sstatic.net/WnHTk.jpg [10]: https://i.sstatic.net/zMgS1.jpg [11]: https://i.sstatic.net/t6vNR.jpg