higher consumption observed by NPN BJT when REG1 is used to drive MCU for 2.7 uA load

Embedded Developer

Part Number: BQ76952
Other Parts Discussed in Thread: TIDA-010208

Tool/software:

Hi, please find the our using design referring to TIDA-010208

current going into R146/ into external NPN BJT is 3 mA,

current going out of LP_3V3 or to MCU connected is 2.7 uA, the connection to buck enable trace is disconnected, basically R144 is DNP, following current were observed by connecting digital mustimeters in series

we don't understand why is BJT suggested in reference schematic TIDA-010208 consuming such high current

the AFE is in NORMAL mode which we think shouldn't concern this circuit containing BREG, REGIN, and REG1

Is there a minimum consumption when external BJT and REG1 is enabled

Regards

5 months ago

0 Kian Lin 5 months ago

TI__Expert 4220 points

Hi,

Sorry for the late reply. I am just aware of this thread.

What's the load on REG2? Did you test the current across R143?

BRs

Kian

0 Embedded Developer 5 months ago in reply to Kian Lin

Intellectual 315 points

Hi,

There is no load on REG2,
The current measured across R143 is 12.5 uA, while the MCU is consuming 2.43 uA.

Regards

0 Kian Lin 5 months ago in reply to Embedded Developer

TI__Expert 4220 points

Hi，

12.5uA base current does mean you have 2-3mA load on the emitter electrode. No internal circuit could cause this large load current on REG1.

Could you show me the full schematic? You can email me if you don't want to attach it in this forum.

BRs

Kian

0 Embedded Developer 4 months ago in reply to Kian Lin

Intellectual 315 points

Hi,

Could you please share the email ID where we can send the schematic?

Regards

0 Kian Lin 4 months ago in reply to Embedded Developer

TI__Expert 4220 points

Hi,

My email address is kian-lin@ti.com

BRs

Kian

0 Embedded Developer 4 months ago in reply to Kian Lin

Intellectual 315 points

Hi Kian,

I had mailed you the schematic, awaiting your response. Please check the spam inbox as well.

Regards

0 Kian Lin 4 months ago in reply to Embedded Developer

TI__Expert 4220 points

Hi，

I checked my mailbox and don't see your email. You can share your company email address and then I can send a message to you.

BRs

Kian

0 Embedded Developer 4 months ago in reply to Kian Lin

Intellectual 315 points

Hi,

Sorry for the late reply, my email address is akshat@vecmocon.com

Regards

Power management

Power management forum

higher consumption observed by NPN BJT when REG1 is used to drive MCU for 2.7 uA load