GND

V

DD

RESET

RST

TLV803M

Microprocessor

100kW

0.1 mF

5.0V

GND

V

DD

RESET

TLV803S

0.1 mF

3.3V

V

IO

V

CORE

3.3V

100kW

TLV803S

V

DD

3.3V

RESET

GND

47kW RST

Microprocessor

V

CC

TLV803M, TLV803R

TLV803S, TLV803Z

www.ti.com

SBVS157A

– APRIL 2011 – REVISED JUNE 2011

MONITORING MULTIPLE SUPPLIES

Because the TLV803 has an open-drain output, multiple TLV803 outputs can be directly tied together to form a

logical OR-ing function for the RESET line. Only one pull-up resistor is required for this configuration. Figure 9

shows two TLV803s connected together to provide monitoring of a 3.3-V power rail and a 5.0-V power rail. A

reset is generated if either power rail falls below the threshold voltage of its corresponding TLV803.

Figure 9. Multiple Voltage Rail Monitoring

BIDIRECTIONAL RESET PINS

Some microcontrollers have bidirectional reset pins that act as both inputs and outputs. In a situation where the

TLV803 is pulling the RESET line low while the microcontroller is trying the force the RESET line high, a series

resistor should be placed between the output of the TLV803 and the RESET pin of the microcontroller to protect

against excessive current flow. Figure 10 shows the connection of the TLV803 to a microcontroller using a series

resistor to drive a bidirectional RESET line.

Figure 10. Connection to Bidirectional Reset Pin

Copyright

© 2011, Texas Instruments Incorporated

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Product Folder Link(s): TLV803M TLV803R TLV803S TLV803Z