LTC2972 datasheet(91/112 Pages) LINER

91 / 112 page

LTC2972

2972fa

For more information www.linear.com/LTC2972

APPLICATIONS INFORMATION

The input current sense path includes an internal,

anti-aliasing low pass filter with typical 32dB rejection at

62.5kHz. To improve high frequency current sense com-

mon mode rejection, add a 0.01µF capacitor, CIN, to the

VIN_SNS_CAP pin.

The Mfr_ein_config_iin_range bits select one of three

input current sense amplifier ranges: high, medium and

low. The RSENSE value should be chosen to satisfy the

input range. The maximum allowable input ranges are as

follows: ±100mV range for high range,±50mV for medium

range and ±20mV for low range. For best accuracy, use

the lowest range setting encompassing the maximum

input signal.

To help choose the RSENSE value and Mfr_ein_config_

iin_range setting for your application, use the Electrical

Characteristics table for TUE_IIN, along with Figures 25

and 26. Figures 25 and 26 serve as extrapolated guides

while the Electrical Characteristics table shows tested

TUE_IIN conditions. After selecting RSENSE, write its value

in mΩ to the MFR_IIN_CAL_GAIN register, and READ_IIN

will return the sensed current in amps. Figures 25 and 26

show absolute value of the expected worst case READ_IIN

Total Unadjusted Error, TUE_IIN, in µV and in relative % of

current sense input voltage reading, VIIN_SNS, as a func-

tion of VIIN_SNS (VIIN_SNSP – VIIN_SNSM) for high range,

medium range and low range settings.

Figure 25. TUE_IIN vs READ_IIN Input Voltage in µV

Figure 26. TUE_IIN vs READ_IIN Input Voltage in Percentage

Figure 27. Optional VIN_SNS Filtering

VIIN_SNS (mV)

50 60 70 80 90

700

600

500

400

300

200

100

2972 F25

10 20 30 40

100

HIGH RANGE

MEDIUM RANGE

LOW RANGE

HIGH RANGE

LOW RANGE

MEDIUM RANGE

VIIN_SNS (mV)

100

0.5

2972 F27

VIN_SNS

4.5V < VIN_SNS < 15V

IIN_SNSP

IIN_SNSM

VIN_SNS_CAP

LTC2972*

GND

350Ω

*SOME DETAILS OMITTED FOR CLARITY

2972 F28

LOAD

CIN

0.01µF

1µF

10µF

100Ω

10Ω

100Ω

RSENSE

LTC2972 Datasheet(PDF) 91 Page - Linear Technology

LTC2972 Datasheet(HTML) 91 Page - Linear Technology

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 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL