TMCS1101 datasheet(17/31 Pages) TI1

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TMCS1101

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SBOS825 – SEPTEMBER 2019

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Feature Description (continued)

9.3.5 Current-Sensing Measurable Ranges

The TMCS1101 measurable input current range depends on the device variant, as well as the analog supply VS.

The output voltage is a first-order linear function of the input current, as shown in Equation 1, and is only limited

by VOUT swing to either supply or ground. The linear output swing range to both VS and GND is calculated by

equations Equation 14 and Equation 15.

VOUT,max = VS – SwingVS

(14)

VOUT,min = SwingGND

(15)

Rearranging the transfer function of the device to solve for input current and substituting VOUT,max and VOUT,min

yields maximum and minimum measurable input current ranges described by Equation 16 and Equation 17.

IIN,MAX+ = (VOUT,max – VOUT,0A) / S

(16)

IIN,MAX- = (VOUT,0A – VOUT,min) / S

where

•

IIN,MAX+ is the maximum linear measurable positive input current.

•

IIN,MAX- is the maximum linear measurable negative input current.

•

S is the sensitivity of the device variant.

•

VOUT,0A is the appropriate zero current output voltage.

(17)

TMCS1101A<1-4>B variants accommodate bidirectional current sensing by creating zero-current output voltage

equal to half of the supply (VS) potential, while TMCS1101A<1-4>U variants provide most of the dynamic

measurable range for positive currents.

9.4 Device Functional Modes

9.4.1 Power-Down Mode

As a result of the inherent galvanic isolation of the device, very little consideration must be paid to powering

down the device, as long as the limits in the Absolute Maximum Ratings table are not exceeded on any pins. The

isolated current input and the low-voltage signal chain can be decoupled in operational behavior, as either can be

energized with the other shut down, as long as the isolation barrier capabilities are not exceeded. The low-

voltage power supply can be powered down while the isolated input is still connected to an active high-voltage

signal or system.

TMCS1101 Datasheet(PDF) 17 Page - Texas Instruments