msp430 f5328
DESCRIPTION
Vbatt. LDO. 3.3V. 330. MSP430 F5328. P6.0 P6.1. 330. Gnd. To measure Vbatt : Drive P6.1 low, current flows through 2*330 ohm resistors Measure voltage at P6.0 (and 6.1 and subtract offset since it’s not 0, about 200mV) Switch P6.1 back to an input - PowerPoint PPT PresentationTRANSCRIPT
MSP430F5328
LDO
330
330
Vbatt
3.3V
P6.0P6.1
Gnd
To measure Vbatt:Drive P6.1 low, current flows through 2*330 ohm resistorsMeasure voltage at P6.0 (and 6.1 and subtract offset since it’s not 0, about 200mV)Switch P6.1 back to an input330 chosen so that current is at least 10* other system current
MSP430F5328
LDO
330
330
Vbatt
3.3V
P6.0P6.1
Gnd
Problem when P6.1 floating:Vbatt is 4.2V, Vcc 3.3VSo current is flowing into MSP430 through P6.0 (into the substrate???)Questions:
What will be the voltage at P6.0?Therefore what current is flowing out of the battery