TPS3610U18, TPS3610T50

BATTERY BACKUP SUPERVISORS FOR RAM RETENTION

SLVS327B – DECEMBER 2000 – REVISED DECEMBER 2002

8

POST OFFICE BOX 655303

detailed description (continued)

power-fail comparator (PFI and PFO)

An additional comparator is provided to monitor voltages other than the nominal supply voltage. The

power-fail-input (PFI) is compared with an internal voltage reference of 1.15 V. If the input voltage falls below

power consumption and also to assure that the current in the PFI pin can be neglected compared with the current

through the resistor network. The tolerance of the external resistors should be not more than 1% to ensure

minimal variation of sensed voltage. If the power-fail comparator is unused, PFI should be connected to ground

and PFO left unconnected.

LOWLINE

a nonmaskable interrupt (NMI) to the processor when power begins to fall. In most battery-operated portable

systems, reserve energy in the battery provides enough time to complete the shutdown routine once the low-line

time, such as when the main battery is disconnected or a high-side switch is opened during normal operation,

C

I

L

t

sd

V

0.012

BATTON

Most often BATTON is used as a gate drive for an external pass transistor for high-current applications. In

BATTON can be connected directly to the gate of a PMOS transistor (see Figure 3). No current-limiting resistor

is required. If a PMOS transistor is used, it must be connected in the reverse of the traditional method (see

through the FET when its gate is high.

TPS3610

VDD

VOUT

BATTON

DS

G

GND

PMOS FET

Body Diode

Figure 3. Driving an External MOSFET Transistor With BATTON