Features

• Regulated Negative Voltage from a Single Positive Supply
• Low Output Ripple: Less Than 1mVP-P Typ
• High Charge Pump Frequency: 900kHz Typ
• Small Charge Pump Capacitors: 0.1µF
• Requires Only Four External Capacitors
• Fixed ±4.1V, ±2.5V, ±2V or Adjustable Output
• Shutdown Mode Drops Supply Current to <1µA
• High Output Current: Up to 20mA (Depending on VCC to VOUT Range)
• Output Regulation: 2.5% Over Line, Load and Temperature
• Available in 8-Lead MSOP, 8-Lead Narrow SO and 16-Lead Narrow SSOP

Typical Application

Description

The LTC1550L/LTC1551L are switched capacitor charge 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 ripple voltages typically below 1mV_P-P. The LTC1550L is 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 0.2µA 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 0.1µF charge pump capacitors and a filter capacitor at the linear regulator output. The adjustable LTC1550L/LTC1551L require two additional resistors to set the output voltage. The LTC1550L/LTC1551L will supply up to 20mA (depending on V_CC to V_OUT range), 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.