Prince Charming
Member level 2
I have the circuit below: [moderator action: removed link to external file server] Now focus your attention on TP4056 charging and protection module because it has DW01A battery protection circuit in it which detects over current at 3A. Also focus your attention to SX1308 Boost converter which boosts Single cell voltage to 24V which means it draws high current. Also beware that J10 will be connected with an alarm which draws around 140mA and the Flasher LED which draws 125mA current in steady state. Flasher flashes in 2.5Hz (200ms on 200ms off) rate. Also notice that I've added 470uF capacitor between pin 3 and 4 of SX1308 to lower the voltage ripple. Because originally SX1308 has 33uF capacitor at the output.
Problem: When alarm starts to ring (as microcontroller activates Q2) in a really brief moment the alarm and also the whole system suddenly stops. When I remove the 470uF capacitor it rings longer but the sound is discrete and eventually the system completely turns off. But the boost converter draws:
My diagnostic: During the turn on of the Flasher LED it discharges the capacitor instantly. When it is turned off the capacitor is quite empty and it draws high current during charging, if this were to happen for once the battery protector wouldn't make it a problem because it has a high current tolerance duration around 50ms. But this high current is constantly being drawn several times in a second and it triggers the protection circuit thus shuts the system down.
Question1: How to lower the inrush current of output capacitor of a boost converter which has a switching load which causes current spikes?
Question2: Can I use pin 3 and 4 of U1 to power the system and leave 5-6 floating to disable current protection circuit but only keeping the charging circuit part?
Problem: When alarm starts to ring (as microcontroller activates Q2) in a really brief moment the alarm and also the whole system suddenly stops. When I remove the 470uF capacitor it rings longer but the sound is discrete and eventually the system completely turns off. But the boost converter draws:
(140+125) * 8 * 100/90 = 2355 mA
which is les than 3A. When I remove the Flasher LED, everything works fine.Note: "8" comes form the power equality V1 I1 = V2 I2 and we are boosting 3V to 24V. "100/90" comes because of efficiency.
My diagnostic: During the turn on of the Flasher LED it discharges the capacitor instantly. When it is turned off the capacitor is quite empty and it draws high current during charging, if this were to happen for once the battery protector wouldn't make it a problem because it has a high current tolerance duration around 50ms. But this high current is constantly being drawn several times in a second and it triggers the protection circuit thus shuts the system down.
Question1: How to lower the inrush current of output capacitor of a boost converter which has a switching load which causes current spikes?
Question2: Can I use pin 3 and 4 of U1 to power the system and leave 5-6 floating to disable current protection circuit but only keeping the charging circuit part?
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