LT1638CS8 datasheet(16/16 Pages) LINER

16 / 16 page

LT1638/LT1639

16389fd

LT 0707 REV D • PRINTED IN USA

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

TYPICAL APPLICATION

RA, 2k

2N3904

S1 = OPEN, GAIN = 1

S1 = CLOSED, GAIN = 10

RA = RB

VS = 5V, 0V

10k

90.9k

VOUT

LOGIC

1638/39 F05

LOGIC HIGH (5V) = CHARGING

LOGIC LOW (0V) = DISCHARGING

10k

2N3904

RS, 0.2Ω

CHARGER

VOLTAGE

RA', 2k

RB', 2k

RB, 2k

VBATT = 12V

IBATT

LOAD

VOUT

(RS)(RG/RA)(GAIN)

VOUT

GAIN

IBATT =

AMPS

–

1/4 LT1639

–

1/4 LT1639

–

1/4 LT1639

–

1/4 LT1639

Figure 5. Battery Monitor

PART NUMBER

DESCRIPTION

COMMENTS

LT1078/LT1079

Dual/Quad 55

μA Max, Single Supply, Precision Op Amps

Input/Output Common Mode Includes Ground, 70

μV VOS(MAX)

LT2078/LT2079

and 2.5

μV/°C Drift (Max), 200kHz GBW, 0.07V/μs Slew Rate

LT1178/LT1179

Dual/Quad 17

μA Max, Single Supply, Precison Op Amps

Input/Output Common Mode Includes Ground, 70

μV VOS(MAX)

LT2178/LT2179

and 4

μV/°C Drift (Max), 85kHz GBW, 0.04V/μs Slew Rate

LT1366/LT1367

Dual/Quad Precision, Rail-to-Rail Input and Output Op Amps

475

μV VOS(MAX), 500V/mV AVOL(MIN), 400kHz GBW

LT1490/LT1491

Dual/Quad Over-The-Top Micropower, Rail-to-Rail Input and

Single Supply Input Range: – 0.4V to 44V, Micropower 50

μA

Output Op Amps

per Amplifier, Rail-to-Rail Input and Output, 200kHz GBW

LT1636

Single Over-The-Top Micropower Rail-to-Rail Input and Output

μA Supply Current, VCM Extends 44V above VEE,

Op Amp

Independent of VCC; MSOP Package, Shutdown Function

RELATED PARTS

The battery monitor in Figure 5 also demonstrates the

LT1638’s ability to operate with its inputs above the

positive rail. In this application, a conventional amplifier

would be limited to a battery voltage between 5V and

ground, but the LT1638 can handle battery voltages as

high as 44V. When the battery is charging, Amp B senses

the voltage drop across RS. The output of Amp B causes

Q2 to drain sufficient current through RB to balance the

input of Amp B. Likewise, Amp A and Q1 form a closed

loop when the battery is discharging. The current through

Q1 or Q2 is proportional to the current in RS and this

current flows into RG and is converted into a voltage. Amp

D buffers and amplifies the voltage across RG. Amp C

compares the output of Amp A and Amp B to determine

the polarity of current through RS. The scale factor for

VOUT with S1 open is 1V/A. With S1 closed the scale factor

is 1V/100mA and currents as low as 500

μA can be

measured.

LT1638CS8 Datasheet(PDF) 16 Page - Linear Technology

LT1638CS8 Datasheet(HTML) 16 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Datasheet Download

Link URL