LT1638 LINER [Linear Technology], LT1638 Datasheet - Page 10

• Manufacturer Part Number: LT1638
• Description: 1.2MHz, 0.4V/us Over-The-TopTM Micropower Rail-to-Rail Input and Output Op Amps
• Manufacturer: LINER [Linear Technology]

LT1638/LT1639
TYPICAL APPLICATIONS
proportional to the load current. As a convenient monitor,
the 2k load resistor converts the current into a voltage. The
positive supply rail, V
the op amp and could be as high as 44V.
SI PLIFIED SCHE ATIC
PACKAGE
10
W
Figure 3. Positive Supply Rail Current Sense
LOAD
ONE AMPLIFIER
V
+
+
R1
6k
0.2
10 A
200
200
I
Q5
LOAD
DESCRIPTION
Q1
Q4
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
(0.18)
0.007
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
V
+
OUT
, is not limited to the 5V supply of
+
–
1/2 LT1638
– IN
+IN
= (2 )(I
Q6
5V
(0.53 0.015)
0.021 0.006
R2
R3
W
1k
1k
LOAD
)
U
D4
Q1
2N3904
0 – 6 TYP
2k
U
1638/39 F03
D5
Q9
0V TO 4.3V
Dimensions in inches (millimeters) unless otherwise noted.
Q7
D1
SEATING
PLANE
Q8
Q10
0.040 0.006
(LTC DWG # 05-08-1660)
(1.02 0.15)
0.012
(0.30)
8-Lead Plastic MSOP
REF
D2
MS8 Package
0.0256
(0.65)
TYP
Q11
Q2
Q12
The Figure 4 application uses the LT1638 in conjunction
with the LT1634 micropower shunt reference. The supply
current of the op amp also biases the reference. The drop
across resistor R1 is fixed at 1.2V generating an output
current equal to 1.2V/R1.
(0.86 0.102)
0.034 0.004
Q13
(0.15 0.102)
0.006 0.004
R4
8k
(3.00 0.102)
0.118 0.004*
Q14
R5
8k
0.192 0.004
(4.88 0.10)
LT1634-1.2
Figure 4. Current Source
Q15
D3
+
–
1/2 LT1638
1
8
V
Q3
Q16
CC
7 6 5
2 3
4
Q17
Q18
MSOP (MS8) 1197
(3.00 0.102)
0.118 0.004**
V
CC
Q19
R1
1638/39 F04
I
OUT
Q20
I
Q21
Q22
OUT
1638/39 SS
OUT
=
1.2V
R1
V
V
+
–