LT1787HV_15 Datasheet, PDF (1/16 Pages) Linear Technology – Precision, High Side Current Sense Amplifiers

LT1787/LT1787HV
Precision, High Side
Current Sense Amplifiers
FEATURES
■ _{Input Offset Voltage: 75µV (Max)}
■ _{60V Supply Operation (LT1787HV)}
■ _{12-Bit Dynamic Range}
■ _{Operating Current: 60µA}
■ _{User-Selectable External Sense Resistor}
■ _{Bidirectional High Side Current Sensing}
■ _{Unidirectional or Bidirectional Output}
■ _{Input Noise Filtering}
■ _{–40°C to 125°C Operating Temperature Range}
■ _{Available in 8-Lead SO and MSOP Packages}
U
APPLICATIO S
■ _{Battery Monitoring}
■ _{Power Monitoring}
■ _{Portable Phones}
■ _{Cellular Phones}
■ _{Portable Test/Measurement Systems}
■ _{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 indicates 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.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
12-Bit Dynamic Resolution Unidirectional Output into LTC^®1286 ADC
TO
LOAD
R_SENSE
I = 100A ^0.0016Ω
1 _FIL–
FIL^{+ 8}
2 ^VS– ^{LT1787HV V}S+ 7
3
DNC
4
V_EE
V_{BIAS 6}
R_OUT
20k ₅
V_OUT
V_OUT = V_BIAS + (8 • I_LOAD • R_SENSE)
C2
0.1µF
2.5V TO 60V
R1
C1
15k
1µF
V_REF V_CC
+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 60
TOTAL SUPPLY VOLTAGE (V)
1787 TA01b
1787fc
1