1 Features

1• 1.4-MHz Switching Frequency

• Low R DS(ON) DMOS FET

• 1-mVp-p Output Ripple

• −5 V at 300 mA From 5-V Input

• Better Regulation Than a Charge Pump

• Uses Tiny Capacitors and Inductors

• Wide Input Range: 2.7 V to 14 V

• Low Shutdown Current: <1 μA

• 5-Pin SOT-23 Package

2 Applications

• MR Head Bias

• Digital Camera CCD Bias

• LCD Bias

• GaAs FET Bias

• Positive to Negative Conversion

3 Description

The LM2611 is a current mode, PWM inverting

switching regulator. Operating from a 2.7-V to 4-V

supply, it is capable of producing a regulated

negative output voltage of up to −(36 VIN(MAX)). The

LM2611 utilizes an input and output inductor, which

enables low voltage ripple and RMS current on both the input and the output. With a switching frequency

of 1.4 MHz, the inductors and output capacitor can be

physically small and low cost. High efficiency is

achieved through the use of a low RDS(ON) FET.

The LM2611 features a shutdown pin, which can be

activated when the part is not needed to lower the Iq

and save battery life. A negative feedback (NFB) pin

provides a simple method of setting the output

voltage, using just two resistors. Cycle-by-cycle

current limiting and internal compensation further

simplify the use of the LM2611.

The LM2611 is available as a small 5-pin, SOT-23

package and comes in two grades. Grade A has a

1.2-A current limit and 0.5-Ω RDS(ON), and Grade B

has a 0.9-A current limit and 0.7-Ω RDS(ON).