LT1638HS8 Linear Technology, LT1638HS8 Datasheet - Page 18

• Manufacturer Part Number: LT1638HS8
• Description: IC OPAMP R-R IN/OUT DUAL 8-SOIC
• Manufacturer: Linear Technology
• Series: Over-The-Top®r

Specifications of LT1638HS8

• Amplifier Type: General Purpose
• Number Of Circuits: 2
• Output Type: Rail-to-Rail
• Slew Rate: 0.4 V/µs
• Gain Bandwidth Product: 1.2MHz
• Current - Input Bias: 20nA
• Voltage - Input Offset: 250µV
• Current - Supply: 205µA
• Current - Output / Channel: 40mA
• Voltage - Supply, Single/dual (±): 2.5 V ~ 44 V, ±1.25 V ~ 22 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• -3db Bandwidth: -

LT1638/LT1639
TYPICAL APPLICATION
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 amplifi er
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 R
Q2 to drain suffi cient current through R
input of Amp B. Likewise, Amp A and Q1 form a closed
RELATED PARTS
PART NUMBER
LT1078/LT1079
LT2078/LT2079
LT1178/LT1179
LT2178/LT2179
LT1366/LT1367
LT1490/LT1491
LT1636
18
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone]
CHARGER
VOLTAGE
DESCRIPTION
Dual/Quad 55μA Max, Single Supply, Precision Op Amps
Dual/Quad 17μA Max, Single Supply, Precison Op Amps
Dual/Quad Precision, Rail-to-Rail Input and Output Op Amps
Dual/Quad Over-The-Top Micropower, Rail-to-Rail Input and
Output Op Amps
Single Over-The-Top Micropower Rail-to-Rail Input and Output
Op Amp
●
FAX: [phone]
S
I
BATT
LOAD
. The output of Amp B causes
=
R
S
I
(R
BATT
, 0.2Ω
S
)(R
+
G
V
/R
OUT
●
A
)(GAIN)
R
R
V
R A , 2k
R
www.linear.com
BATT
A
B
B
B
',
'
, 2k
, 2k
2k
to balance the
= 12V
=
V
GAIN
OUT
Figure 5. Battery Monitor
1/4 LT1639
–
1/4 LT1639
–
+
+
AMPS
A
B
2N3904
S1
S1 = OPEN, GAIN = 1
S1 = CLOSED, GAIN = 10
loop when the battery is discharging. The current through
Q1 or Q2 is proportional to the current in R
rent fl ows into R
D buffers and amplifi es the voltage across R
compares the output of Amp A and Amp B to determine
the polarity of current through R
V
factor is 1V/100mA and currents as low as 500μA can
be measured.
Q2
OUT
2N3904
with S1 open is 1V/A. With S1 closed the scale
COMMENTS
Input/Output Common Mode Includes Ground, 70μV V
and 2.5μV/°C Drift (Max), 200kHz GBW, 0.07V/μs Slew Rate
Input/Output Common Mode Includes Ground, 70μV V
and 4μV/°C Drift (Max), 85kHz GBW, 0.04V/μs Slew Rate
475μV V
Single Supply Input Range: – 0.4V to 44V, Micropower 50μA
per Amplifi er, Rail-to-Rail Input and Output, 200kHz GBW
55μA Supply Current, V
Independent of V
10k
Q1
R
10k
G
OS(MAX)
G
1/4 LT1639
1/4 LT1639
, 500V/mV A
+
–
+
–
and is converted into a voltage. Amp
LOGIC HIGH (5V) = CHARGING
LOGIC LOW (0V) = DISCHARGING
CC
R
V
; MSOP Package, Shutdown Function
C
D
S
A
= R
= 5V, 0V
CM
90.9k
B
Extends 44V above V
© LINEAR TECHNOLOGY CORPORATION 1998
VOL(MIN)
1638/39 F05
S
, 400kHz GBW
. The scale factor for
LT 0910 REV F • PRINTED IN USA
LOGIC
V
OUT
S
EE
and this cur-
,
G
OS(MAX)
OS(MAX)
. Amp C
16389ff