4-27

TELCOM SEMICONDUCTOR, INC.

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8

REGULATED GaAs FET BIAS SUPPLY

TCM850

TCM851

TCM852

TCM853

FEATURES

s

Fixed – 4.1V or Adjustable – 0.5V to – 9V Output

at 5mA

s

4.5V to 10V Input Voltage Range

s

Low Output Voltage Ripple

TCM850-852 .............................................. 2mVp-p

TCM853 ...................................................... 1mVp-p

s

100kHz Charge Pump Switching Frequency

s

Optional External Synchronizing Clock

Input (TCM852)

s

Logic Level Shutdown Mode ................ 0.5

Temperature (TCM850/852/853)

s

Low Cost, 8-Pin SOIC Package

APPLICATIONS

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Cellular Phones

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Negative Regulated Power Supplies

s

LCD Bias Contrast Control

s

Adjustable GaAs FET Bias

s

Wireless Data Loggers

GENERAL DESCRIPTION

The TCM850/1/2/3 combines an inverting charge pump

and a low noise linear regulator in a single small outline

package. They are ideal for biasing GaAS FETs in cellular

telephone transmitter power amplifiers

All four devices accept a range of input voltages from

4.5V to 10.0V and have – 5mA output current capability. The

TCM850/1/2 have both preset (– 4.1V) and variable (– 0.5V

to –9.0V) output voltages that program with an external

resistor divider. The TCM853 output voltage programs with

an external positive control voltage. The TCM850/1/3 can

be shutdown reducing quiescent current to less than

0.5

µA (typ) over temperature, 2µA (typ) for the TCM851.

CHARGE

PUMP

GND

N

FB

(GND to SET

OUT

NEGOUT

SHDN (TCM850)

SHDN (TCM851)

OSC (TCM852)

IN

TCM850

TCM851

TCM852

– 1.28V

REF

CHARGE

PUMP

GND

CONT

(CONTROL VOLTAGE)

OUT

NEGOUT

SHDN

IN

TCM853

N

+

–

+

–

ORDERING INFORMATION

Part No.

Package

Temp. Range

TCM850COA

8-Pin SOIC

0

°C to +70°C

TCM850EOA

8-Pin SOIC

– 40

°C to +85°C

TCM851COA

8-Pin SOIC

0

°C to +70°C

TCM851EOA

8-Pin SOIC

– 40

°C to +85°C

TCM852COA

8-Pin SOIC

0

°C to +70°C

TCM852EOA

8-Pin SOIC

– 40

°C to +85°C

TCM853COA

8-Pin SOIC

0

°C to +70°C

TCM853EOA

8-Pin SOIC

– 40

°C to +85°C

TCM850EV

Evaluation Kit for

TCM850/1/2/3

FUNCTIONAL BLOCK DIAGRAM

TC850/1/2/3-3 10/1/96

Figure 1.

EVALUATION

KIT

AVAILABLE