TPS77001, TPS77012, TPS77015, TPS77018, TPS77025

TPS77027, TPS77028, TPS77030, TPS77033, TPS77050

ULTRA LOW-POWER 50-mA LOW-DROPOUT LINEAR REGULATORS

SLVS210C – JUNE 1999 – REVISED SEPTEMBER 1999

13

POST OFFICE BOX 655303

APPLICATION INFORMATION

output voltage programming

The output voltage of the TPS77001 adjustable regulator is programmed using an external resistor divider as

shown in Figure 22. The output voltage is calculated using:

V

O +

V

ref

1

) R1

R2

(1)

where

Resistors R1 and R2 should be chosen for approximately 7-

µA divider current. Lower value resistors can be

used but offer no inherent advantage and waste more power. Higher values should be avoided as leakage

currents at FB increase the output voltage error. The recommended design procedure is to choose

R2 = 169 k

Ω to set the divider current at 7 µA and then calculate R1 using:

R1

+

V

O

V

ref

* 1

R2

(2)

VO

VI

OUT

FB

R2

GND

EN

IN

TPS77001

1

µF

OUTPUT

VOLTAGE

(V)

R1

R2

2.5

3.3

3.6

4.0

5.0

174

287

324

383

523

169

169

169

169

169

OUTPUT VOLTAGE

PROGRAMMING GUIDE

DIVIDER RESISTANCE

(k

Ω)‡

‡ 1% values shown.

3

1

4

2

R1

5

ESR = 0.2

Ω

4.7

µF

Figure 22. TPS77001 Adjustable LDO Regulator Programming