AMC7834 Datasheet, PDF (38/93 Pages) Texas Instruments – AMC7834 12-Bit Integrated Power-Amplifier Monitor and Control System with Temperature, Current and Voltage Supervision Capabilities

AMC7834
SLAS972B – NOVEMBER 2014 – REVISED MARCH 2016
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The maximum differential voltage, V_SENSE, supported by the AMC7834 current-sense amplifiers is 200 mV. Use
Equation 6 to calculate the R_(SENSE) value.
R_(SENSE) = V_SENSE / I_Lmax
(6)
The maximum power dissipation of the sense resistor should not be exceeded. Use Equation 7 to calculate the
maximum sense resistor power dissipation.
P_R(SENSE) = V_SENSE × I_Lmax
(7)
The current sensors operate as four standalone current-sense amplifiers when the AMC7834 is set in open-loop
mode (LOOP-EN bit set to 0 in register 0x10). In open-loop mode the current-sense amplifier outputs are
converted by the device ADC and the results are stored in straight binary format in the CS-Data registers
(address 0x29 through 0x2B). Use Equation 8 to calculate the differential voltage, V_SENSE.
V_SENSE
CODE u 0.2
4096
(8)
Alternatively, with the AMC7834 set in closed-loop mode (LOOP-EN bit set to 1 in register 0x10) the current
sensors operate as part of four independent closed-loop current controllers. In closed-loop operation, four
autonomous closed-loop current controllers are implemented by continuously adjusting the bipolar DAC outputs
in response to the current-sense amplifier outputs (see the Closed-Loop Mode section).
The AMC7834 device enables digital filtering of the current sense measurements to improve their accuracy at the
cost of a longer update time. The current sense digital filter is enabled by the CS-FILTER[2:0] setting in register
0x10 and its corresponding transfer function is given by Equation 9.
Hz
1
1 K 1z¹
(9)
Table 5 lists the K value associated with each of the allowable CS-FILTER[2:0] settings as well as the
corresponding update time.
Table 5. Current Sense Digital Filter Configuration
CS-FILTER[2:0]
000
001
010
011
100
All others
K
UPDATE TIME
(ms)
1
0.2
2
3.4
4
6.6
8
13
16
25.6
Not valid
38
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