Commit 1bff4d5f authored by Ruben Castro's avatar Ruben Castro

Update README.md

parent 3b1f3921
Hello!
This is my first attempt at a circuit board. It shall hold an H-bridge for This is my first attempt at a circuit board. It shall hold an H-bridge for
motor control, current sensing, and SPI pins for encoder implementation. motor control, current sensing, and SPI pins for encoder implementation.
It is a board that revolves around the DRV8701 (http://www.ti.com/product/DRV8701) It is a board that revolves around the DRV8701 (http://www.ti.com/product/DRV8701)
gate driver chip. The DRV8701 is capable of driving a varied set of MOSFETS. gate driver chip. The DRV8701 is capable of driving a varied set of MOSFETS.
Chosen here are the AON7410 MOSFETS. Chosen here are the AON7410 MOSFETS.
Design Rules: ## Design Rules:
-5A continuous/10A peak rating -5A continuous/10A peak rating
-0-10A to 0-1.5V mapping current sensing -0-10A to 0-1.5V mapping current sensing
-12V Motor -12V Motor
...@@ -13,7 +12,7 @@ Design Rules: ...@@ -13,7 +12,7 @@ Design Rules:
-Not hotter than 70C -Not hotter than 70C
DRV8701 Rules: ## DRV8701 Rules:
Vgs(voltage applied to MOSFET gate) = 9.5V Vgs(voltage applied to MOSFET gate) = 9.5V
Ivcp(current capable of being applied to MOSFET gate - dependent on Vm) = 12mA Ivcp(current capable of being applied to MOSFET gate - dependent on Vm) = 12mA
20v/v conversion for current sense - for 0-10A to 0-1.5V mapping, you need a ~7 mOhm resistor rated for >=2watts 20v/v conversion for current sense - for 0-10A to 0-1.5V mapping, you need a ~7 mOhm resistor rated for >=2watts
...@@ -22,13 +21,13 @@ Lots of passive components need to be around the IC. ...@@ -22,13 +21,13 @@ Lots of passive components need to be around the IC.
Here is board version 2.0 Here is board version 2.0
TOP ##TOP
![routedTop](media/circuitV2Top.png) ![routedTop](media/circuitV2Top.png)
BOTTOM ##BOTTOM
![routedBottom](media/circuitV2Bottom.png) ![routedBottom](media/circuitV2Bottom.png)
...@@ -38,7 +37,7 @@ BOTTOM ...@@ -38,7 +37,7 @@ BOTTOM
A few concerns here arise with v2.0 that need to be addressed by checking some A few concerns here arise with v2.0 that need to be addressed by checking some
parameters in person, which I shall do tomorrow. parameters in person, which I shall do tomorrow.
Problems #Problems
The fill for GND that goes towards the Motor GND has a choke point at the corner The fill for GND that goes towards the Motor GND has a choke point at the corner
due to the headers for uploading code being right next to the power and GND sources. due to the headers for uploading code being right next to the power and GND sources.
...@@ -54,7 +53,7 @@ shunt resistor. Right now it is set to 7mOhm, which would return to the ADC ...@@ -54,7 +53,7 @@ shunt resistor. Right now it is set to 7mOhm, which would return to the ADC
150mV/A 150mV/A
Solved Problems/Interesting Challenges #Solved Problems/Interesting Challenges
Due to the way the PWR and GND are conected, I had to get creative with the GND Due to the way the PWR and GND are conected, I had to get creative with the GND
planes. With the limited knowledge I have gathered. I limited the motor GND to the planes. With the limited knowledge I have gathered. I limited the motor GND to the
TOP plane, and kept the Bottom ground plane as clear as possible for the Gate Driver TOP plane, and kept the Bottom ground plane as clear as possible for the Gate Driver
...@@ -66,7 +65,7 @@ TOP plane, and kept the Bottom ground plane as clear as possible for the Gate Dr ...@@ -66,7 +65,7 @@ TOP plane, and kept the Bottom ground plane as clear as possible for the Gate Dr
Basic definitions I learned in the process- ##Basic definitions I learned in the process-
Bulk Capacitor - Capacitor used to be capable of taking over battery in certain sags. It is Bulk Capacitor - Capacitor used to be capable of taking over battery in certain sags. It is
set as close to the input as possible. In this case an electrolytic >=10uF. set as close to the input as possible. In this case an electrolytic >=10uF.
...@@ -87,7 +86,7 @@ Net Ties- Just like a trace, except its meant to be isolated from other traces o ...@@ -87,7 +86,7 @@ Net Ties- Just like a trace, except its meant to be isolated from other traces o
Kelvin Connection- Way of connecting traces to Rsense. It just makes sense Kelvin Connection- Way of connecting traces to Rsense. It just makes sense
Take it for granted. Google how to do it. It's very simple. Take it for granted. Google how to do it. It's very simple.
PCB guides: #PCB guides:
45 degree traces only 45 degree traces only
Kelvin Connection for Rsense Kelvin Connection for Rsense
...@@ -99,7 +98,7 @@ Many many more to be copied from my notebook soon. ...@@ -99,7 +98,7 @@ Many many more to be copied from my notebook soon.
Sources: #Sources:
MOSFET: https://www.digikey.com/product-detail/en/alpha-omega-semiconductor-inc/AON7410/785-1581-1-ND/3621507 MOSFET: https://www.digikey.com/product-detail/en/alpha-omega-semiconductor-inc/AON7410/785-1581-1-ND/3621507
......
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