RETURN

OFF

-48V

FB

OUT

IN

EN

TPS79801

GND

1 F

m

1 F

m

R

SET

ON

IN

OUT

FB

GND

EN

TPS79801

Load

V

IN

R

P

IN

OUT

FB

GND

TPS79801

R

1

V

IN

V

OUT

R

2

C

1

V

= 1.275 V (1 + R / R ) + I R

V

= 1.275 V

I

= 0.2 µA at 25°C

Output Range = 1.275 V to 28 V

OUT

2

1

FB

2

FB

FB

EN

TPS79801-Q1, TPS79850-Q1

www.ti.com

SLVS822D

– MARCH 2009 – REVISED AUGUST 2011

APPLICATION INFORMATION

The TPS798xx is a 50-mA high-voltage LDO regulator with micropower quiescent current and shutdown. The

device is capable of supplying 50 mA at a dropout voltage of 300 mV (typ). The low operating quiescent current

(40

μA) drops to 1 μA in shutdown. In addition to the low quiescent current, the TPS798xx incorporates several

protection features that make it ideal for battery-powered applications.

The device is protected against both reverse-input and reverse-output voltages. In battery-backup applications,

where the output can be held up by a backup battery when the input is pulled to ground, the TPS798xx acts as if

it has a diode in series with its output and prevents reverse current flow. Figure 16 and Figure 17 illustrate two

typical applications.

Note:

–48 V can vary from –4 V to –50 V

Figure 16. Constant Brightness for Indicator LED Over Wide Input Voltage Range

Figure 17. Kelvin Sense Connection

Adjustable Operation

The TPS798xx has an output voltage range of 1.275 V to 28 V. The output voltage is set by the ratio of two

external resistors as shown in Figure 18. The feedback loop monitors the output to maintain the voltage at the

250 k

Ω to minimize errors in the output voltage caused by the FB pin bias current. Note that in shutdown, the

output is turned off and the divider current is zero.

Figure 18. Adjustable Operation

Copyright

© 2009–2011, Texas Instruments Incorporated

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