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PDF LT1787HV Data sheet ( Hoja de datos )
| Número de pieza | LT1787HV | |
| Descripción | Precision/ High Side Current Sense Amplifiers | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LT1787/LT1787HV
Precision, High Side
Current Sense Amplifiers
FEATURES
s Input Offset Voltage: 75µV (Max)
s 60V Supply Operation (LT1787HV)
s 12-Bit Dynamic Range
s Operating Current: 60µA
s User-Selectable External Sense Resistor
s Bidirectional High Side Current Sensing
s Unidirectional or Bidirectional Output
s Input Noise Filtering
s Available in 8-Lead SO and MSOP Packages
U
APPLICATIO S
s Battery Monitoring
s Power Monitoring
s Portable Phones
s Cellular Phones
s Portable Test/Measurement Systems
s Battery-Operated Systems
DESCRIPTIO
The LT®1787 is a complete micropower precision high
side current sense amplifier. The LT1787 monitors bidi-
rectional currents via the voltage across an external sense
resistor. A current or voltage output depicts the direction
and magnitude of the sense current. The LT1787 delivers
greater than a 12-bit dynamic range with ultralow 40µV
input offset voltage compared to a typical 250mV full-
scale input voltage. A fixed gain of 8 is set by onboard
precision resistors. Input signal filtering is easily imple-
mented with a capacitor between the FIL– and FIL+ pins.
The LT1787HV operates from 2.5V to 60V total supply
voltage and the LT1787 operates from 2.5V to 36V total
supply voltage. Both versions have a PSRR in excess of
120dB. The LT1787/LT1787HV draw only 60µA and are
available in 8-lead SO and MSOP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
12-Bit Dynamic Resolution Unidirectional Output into LTC®1286 ADC
TO
LOAD
RSENSE
I = 100A 0.0016Ω
1 FIL–
FIL+ 8
2 VS– LT1787HV VS+ 7
3
DNC
4
VEE
VBIAS 6
ROUT
20k 5
VOUT
VOUT = VBIAS + (8 • ILOAD • RSENSE)
C2
0.1µF
2.5V TO 60V
R1 C1
15k 1µF
VREF VCC
+IN
CS
LTC1286 CLK
–IN GND DOUT
LT1634-1.25
5V
TO µP
1787 TA01
Input Offset Voltage vs Supply Voltage
50
40
30
20
10
0
–10
–20
–30
–40
–50
0
10 20 30 40 50
TOTAL SUPPLY VOLTAGE (V)
60
1787 TA01b
1
1 page  
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Supply Voltage
75
70 TA = 85°C
65
60 TA = 25°C
55 TA = –40°C
50
45
VS+ = VS–
40
0 10 20 30 40 50
TOTAL SUPPLY VOLTAGE (V)
60
1787 G10
Negative Input Sense Current vs
Sense Voltage
120
VS = (2.5V + |VSENSE|) TO 60V
110
100
90
80
70 TA = 85°C
60
TA = 25°C
50
40 TA = –40°C
30
–128 –96 –64 –32 0 32 64 96 128
SENSE VOLTAGE (VS+ – VS–) (mV)
1787 G11
LT1787/LT1787HV
Positive Input Sense Current vs
Sense Voltage
60
VS = (2.5V + |VSENSE|) TO 60V
50
40
TA = 85°C
30
20
TA = 25°C
TA = –40°C
10
0
–128 –96 –64 –32 0 32 64 96 128
SENSE VOLTAGE (VS+ – VS–) (mV)
1787 G17
Step Response at
VSENSE = 0V to 10mV
10mV
0V
80mV
0V
COUT = 0pF
Step Response at
VSENSE = 0V to 128mV
100mV
0V
1V
500mV
0V
1787 G12
COUT = 0pF
Step Response at
VSENSE = 0V to 128mV
100mV
0V
1V
500mV
0V
1787 G18
COUT = 1000pF
1787 G13
Step Response at
VSENSE = 0V to –128mV
0V
– 100mV
0V
– 500mV
– 1V
Step Response at
VSENSE = 0V to –128mV
0V
–100mV
0V
–500mV
–1V
Step Response at
VSENSE = – 128mV to 128mV
100mV
0V
– 100mV
1V
0V
–1V
COUT = 0
1787 G19
COUT = 1000pF
1787 G14
COUT = 0
1787 G20
5
5 Page 
LT1787/LT1787HV
APPLICATIONS INFORMATION
Adjusting Gain Setting
The LT1787 may be used in all operating modes with an
external resistor used in place of the internal 20k ROUT
resistor. When an external resistor is used, leave the VBIAS
pin floating or connected to the VOUT pin. This will remove
the internal ROUT from the circuit.
The voltage gain will be gm • ROUT where gm is the
LT1787’s transconductance, 400µA/V typical. A nominal
gain of 40 may be obtained with an external 100k resistor
used in place of the internal 20k ROUT:
AV = gm • ROUT = 400µA/V • 100k = 40
The transconductance gm is set by on-chip resistors on
the LT1787. These resistors match well but have loose
absolute tolerance. This will normally require that the
external gain setting resistor be trimmed for initial accu-
racy. After trimming, the temperature stability of the gm
and therefore gain will be –200ppm/°C.
The only limitations placed upon the resistor choice is care
must be taken not to saturate the internal circuitry by
violating the VOMAX specification of VS + –0.75V.
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.007
(0.18)
0° – 6° TYP
0.021 ± 0.006
(0.53 ± 0.015)
0.040 ± 0.006
(1.02 ± 0.15)
SEATING
PLANE
0.012
(0.30)
REF
0.0256
(0.65)
BSC
0.034 ± 0.004
(0.86 ± 0.102)
0.006 ± 0.004
(0.15 ± 0.102)
* 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
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
0.118 ± 0.004*
(3.00 ± 0.102)
0.193 ± 0.006
(4.90 ± 0.15)
8 76 5
0.118 ± 0.004**
(3.00 ± 0.102)
MSOP (MS8) 1098
1 234
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.010
(0.254
–
–
0.020
0.508)
×
45°
0.008 – 0.010
(0.203 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0°– 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
0.228 – 0.244
(5.791 – 6.197)
0.189 – 0.197*
(4.801 – 5.004)
8 765
1 2 34
0.150 – 0.157**
(3.810 – 3.988)
SO8 1298
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LT1787HV.PDF ] | |
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