1

LTC1550L/LTC1551L

Low Noise, Switched

Capacitor Regulated

Voltage Inverters

The LTC

pump voltage inverters which include internal linear post-

regulators to minimize output ripple. The LTC1550L fixed

output voltage versions include – 4.1V, –2.5V and –2V with

also available in an adjustable output voltage version. The

LTC1550L/LTC1551L are ideal for use as bias voltage

generators for GaAs transmitter FETs in portable RF and

cellular telephone applications.

The LTC1550L/LTC1551L operate from single 2.7V to

5.5V supplies and draw typical quiescent currents of

3.5mA with a 5V supply. Each device includes a TTL

compatible Shutdown pin which drops supply current to

0.2

µA typically. The LTC1550L Shutdown pin is active low

(SHDN), while the LTC1551L Shutdown pin is active high

(SHDN). Only four external components are required: an

input bypass capacitor, two 0.1

µF charge pump capacitors

and a filter capacitor at the linear regulator output. The

adjustable LTC1550L/LTC1551L require two additional re-

sistors to set the output voltage. The LTC1550L/LTC1551L

while maintaining guaranteed output regulation of

±2.5%.

Both fixed voltage and adjustable LTC1550L/LTC1551L

are available in 8-lead MSOP and SO plastic packages: the

adjustable LTC1550L is also available in a 16-pin SSOP

with the REG pin.

, LTC and LT are registered trademarks of Linear Technology Corporation.

5

µs/DIV

1550L/51L TA01a

s

Regulated Negative Voltage from a Single

Positive Supply

s

s

High Charge Pump Frequency: 900kHz

s

Small Charge Pump Capacitors: 0.1

µF

s

Requires Only Four External Capacitors

s

Fixed – 4.1V, –2.5V, –2V or Adjustable Output

s

Shutdown Mode Drops Supply Current to <1

µA

s

High Output Current: Up to 20mA (Depending on

s

Output Regulation: 2.5% Over Line, Load and

Temperature

s

Available in 8-Lead MSOP, 8-Lead Narrow SO and

16-Lead Narrow SSOP

s

GaAs FET Bias Generators

s

Negative Supply Generators

s

Battery-Powered Systems

s

Single Supply Applications

AC COUPLED

2mV/DIV

1

2

3.6V

8

7

REG

SHDN

LTC1550L-2

GND

10

µF

1550L/51L TA01

0.1

µF

R1

10k

POWER VALID

C1

0.1

µF

2.2

µF

3

4

6

5

0.1

µF

+

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO