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).