TPS60200, TPS60201, TPS60202, TPS60203

REGULATED 3.3 V, 100-mA LOW-RIPPLE CHARGE PUMP

LOW POWER DC/DC CONVERTERS

SLVS274 – MARCH 2000

6

POST OFFICE BOX 655303

detailed description (continued)

low-battery detector (TPS60200 and TPS60202)

The low-battery comparator trips at 1.18 V

at which the low-battery warning is issued can be adjusted with a resistive divider as shown in Figure 2. The

sum of resistors R1 and R2 is recommended to be in the 100 k

Ω to 1 MΩ range. When choosing R1 and R2,

be aware of the input leakage current into the LBI pin.

LBO is an open drain output. An external pullup resistor to OUT, or any other voltage rail in the appropriate range,

in the 100 k

Ω to 1 MΩ range is recommended. During start-up, the LBO output signal is invalid for the first 500

µs. LBO is high impedance when the device is disabled. If the low-battery comparator function is not used,

connect LBI to ground and leave LBO unconnected. The low-battery detector is disabled when the device is

switched off.

V

(

TRIP) +

1.18 V

1

) R1

R2

_

+

+

–

VREF

VBAT

IN

R1

LBI

R2

LBO

R3

VO

Figure 2. Programming of the Low-Battery Comparator Trip Voltage

A 100 nF ceramic capacitor should be connected in parallel to R2 if large line transients are expected. These

voltage drops can inadvertently trigger the low-battery comparator and produce a wrong low-battery warning

signal at the LBO pin.

of resistors R1 and R2 equal 1 M

Ω:

R2

+ 1MW

V

LBI

V

Bat

R1

+ 1MW * R2

(1)

(2)

Formulas to calculate the minimum and maximum battery voltage:

V

Bat(min) +

V

LBI(min)

R1

(min) )

R2

(max)

R2

(max)

V

Bat(max) +

V

LBI(max)

R1

(max) )

R2

(min)

R2

(min)

(3)

(4)