1 Features

• 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 V_IN(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 R_DS(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 R_DS(ON), and Grade B has a 0.9-A current limit and 0.7-Ω R_DS(ON).

1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Circuit