LT6003 datasheet(21/30 Pages) AD

21 / 30 page

LTC2066/LTC2067/LTC2068

Rev. B

For more information www.analog.com

APPLICATIONS INFORMATION

90V High Side Current Sense

This micropower precision LTC2066 high side current

sense circuit measures currents from 100μA to 250mA

over a 4.5V to 90V input voltage range.

The output of this circuit is:

VOUT =

ROUT •RSENSE

RIN

ISENSE = 10 •ISENSE

The LTC2066’s low typical input offset voltage of 1μV and

low input bias current of 5pA contribute output errors

that are much smaller than the error due to precision

limitations of the resistors used. Thus, output accuracy

is mainly set by the accuracy of the resistors RSENSE, RIN,

and ROUT. R1 helps cancel out parasitic Seebeck effect

voltages at –IN by balancing with an identical voltage

at +IN.

The LT1389-4.096 reference, along with the bootstrap

circuit composed of M2, R3, and D1, establishes a very

low power isolated 3V rail that protects the LTC2066 from

reaching its absolute maximum voltage of 5.5V while

allowing for much higher input voltages.

Since the LTC2066’s gain-bandwidth product is 100kHz,

it is recommended to use this circuit to measure currents

that do not change faster than 10kHz. Note that the output

filter as drawn will limit the frequency to 1.5Hz, which

optimizes for lowest noise. If this output filter bandwidth

is too narrow, removing C4 leads to an output filter with

318Hz bandwidth, created by C3 and ROUT.

VOUT = 10 • ISENSE

1mV TO 2.5V

VIN

4.5V TO 90V

2066 F11

49.9

0.1%

1N4148

REF

LT1389-4.096

3.3µF

499k

RSENSE

0.1

ROUT

4.99k

0.1%

22µF

100nF

BSP322P

RIN

49.9

0.1%

10µF

BSP322P

ISENSE

100µA to 250mA

LOAD

LTC2066

Figure 11. High Side Current Sense

LT6003 Datasheet(PDF) 21 Page - Analog Devices

LT6003 Datasheet(HTML) 21 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Datasheet Download

Link URL