ben/ObsidianVault
1
0 Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

vault backup: 2026-06-24 17:21:18

Browse Source
This commit is contained in:
ben committed 2026-06-24 17:21:18 -07:00
1 parent 4c7dc9473a
commit ef3f89693b
1 file changed
+10
Download Patch File Download Diff File Expand all files Collapse all files
PCB Design/Music Player/Process.md
+10
View File
@@ -3,6 +3,8 @@
## TPS63020 ## TPS63020
### Choosing an Inductor ### Choosing an Inductor
Neither of the options given in the datasheet are still available so a different inductor will need to be chosen
The equations needed to find the peak current in steady state operation are The equations needed to find the peak current in steady state operation are
Duty cycle boost: $$D=\frac{{V_{OUT} - V_{IN}}}{V_{OUT}}$$ Duty cycle boost: $$D=\frac{{V_{OUT} - V_{IN}}}{V_{OUT}}$$
and peak current: $$I_{PEAK} = \frac{I_{out}}{\eta * (1 - D)} + \frac{{V_{IN} * D}}{2 * f * L}$$ and peak current: $$I_{PEAK} = \frac{I_{out}}{\eta * (1 - D)} + \frac{{V_{IN} * D}}{2 * f * L}$$
@@ -15,3 +17,11 @@ where
First, to calculate the duty cycle boost we can plug in the output voltage (3.3V) and the "minimum input voltage in boost mode" which for the BQ25985 is listed as 2.304V First, to calculate the duty cycle boost we can plug in the output voltage (3.3V) and the "minimum input voltage in boost mode" which for the BQ25985 is listed as 2.304V
$$D = \frac{{3.3 - 2.304}}{3.3} = 0.302$$ $$D = \frac{{3.3 - 2.304}}{3.3} = 0.302$$
Now calculating for $I_{PEAK}$ using the values
- $D = 0.302$ (calculated previously)
- $f = 2.5$ (MHz, typical stated in datasheet)
- $L=1.5$ (uH, value for inductor used)
- $\eta = 0.9$ (efficiency assumption stated in datasheet)
$$I_{PEAK} = \frac{3.3}{0.9 * (1 - 0.302)} + \frac{{2.304 * 0.302}}{2 * 2.5 * 1.5} = 5.346$$
The datasheet states to pick an inductor with a saturation current 20% higher than the calculated value which would mean $$I_{sat} \geq 6.415$$
The []