S E N S E

3

O U T

C H A R G E

C H A R G E

1

R

R

V

I

1

I

R

u

u

: u

+

±

Load

RSENSE

0.2

Ÿ

R1

2 k

V

+

R2

2 k

ICHARGE

+

-

Q1

2N3906

VOUT

Copyright © 2016, Texas Instruments Incorporated

R3

10 k

C1

Optional

16

LM7301

SNOS879I – AUGUST 1999 – REVISED MAY 2016

www.ti.com

Product Folder Links: LM7301

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Copyright © 1999–2016, Texas Instruments Incorporated

8 Applications and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

8.1.1 Handheld Remote Controls

The LM7301 offers outstanding specifications for applications requiring good speed/power trade-off. In

applications such as remote control operation, where high bandwidth and low power consumption are needed,

the LM7301 performance can easily meet these requirements.

8.1.2 Remote Microphone in Personal Computers

Remote microphones in Personal Computers often use a microphone at the top of the monitor which must drive

a long cable in a high noise environment. One method often used to reduce the nose is to lower the signal

impedance, which reduces the noise pickup. In this configuration, the amplifier usually requires 30 db to 40 db of

gain, at bandwidths higher than most low-power CMOS parts can achieve. The LM7301 offers the tiny package,

higher bandwidths, and greater output drive capability than other rail-to-rail input/output parts can provide for this

application.

8.1.3 Optical Line Isolation for Modems

The combination of the low distortion and good load driving capabilities of the LM7301 make it an excellent

choice for driving opto-coupler circuits to achieve line isolation for modems. This technique prevents telephone

line noise from coupling onto the modem signal. Superior isolation is achieved by coupling the signal optically

from the computer modem to the telephone lines; however, this also requires a low distortion at relatively high

currents. Due to its low distortion at high-output drive currents, the LM7301 fulfills this need, in this and in other

telecom applications. See Stability Considerations for methods used to ensure stability under all load conditions.

8.2 Typical Applications

The circuit shown in Figure 27 uses the wide supply voltage range (1.8 V to 32 V), rail-to-rail input and output

voltage capability, and the unity gain stability of the LM7301 to sense the current flow from the power supply to a

load, such as a battery being charged, or any other load. The circuit creates a ground-referenced output voltage,

which varies linearly with the load current, for easy interface to the rest of the circuitry to create fault-protection,

current and power metering, or current regulation functions.

Figure 27. High Side Current Sensing