Texas Instruments TRIS TMS37122 - 2.3 Power-on-reset; Figure 9: Schematic of Reset Flow

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Analog Front End IC TMS37122 - Reference Guide August ’01
2.3 Power-on-reset
The TMS37122 does not include a power-on-reset circuit, which supervises the battery volt-
age. The circuit is reset by the Microcomputer via the WDEEN input (WDEEN='0'). It is ex-
pected that the current Microcomputer RKE system is already equipped with an efficient reset
circuit securing an initialization in case of supply voltage drop below 2 V (2.2 V).
If the Battery Backup function is used, we recommend to use a Low Power Supervisory cir-
cuit (Isupply < 1 µA). One device that could be used is:
- TPS3836/37 (Texas Instruments)
Figure 9: Schematic of Reset Flow
RESET RST
MICROCOMPUTER
VCC
VDD
TPS3836K25
GND VSS
CT
OUT
WDEEN
TMS37122
GND
VBAT
VCCOMR
1
2
3
4
RESET
WDEEN
BATTERY
BACKUP
BATTERY LIFE TIME
VBAT
V
t
td td
tinit tinit