ISL28022 Datasheet, PDF (15/28 Pages) Intersil Corporation – Precision Digital Power Monitor

ISL28022
MODE2
0
0
0
0
1
1
1
1
TABLE 6. OPERATING MODE SETTINGS
MODE1 MODE0
MODE
0
0 Power-Down
0
1 Shunt Voltage, Triggered
1
0 Bus Voltage, Triggered
1
1 Shunt and Bus, Triggered
0
0 ADC Off (disabled)
0
1 Shunt Voltage, Continuous
1
0 Bus Voltage, Continuous
1
1 Shunt and Bus, Continuous
SHUNT VOLTAGE REGISTER 01H (READ-ONLY)
The Shunt Voltage Register reports the measured value across
the shunt pins (Vinp and Vinm) into the register. The shunt
register LSB is independent of PGA range settings. The PGA
setting for the shunt register masks the unused most significant
bit with a sign bit. For lower range of PGA settings, multiple sign
bits are returned by the DPM. Only one sign bit should be used to
calculate the measured value.
Tables 7 through 10 show the weights of each bit for various PGA
ranges. The tables should be used to calculate the measured
value across the shunt pins from the binary to decimal domains.
To calculate the measured decimal value across the shunt, first
read the shunt voltage register. Assume the PGA setting is set to
the 80mV range. For this example, the reading output by the chip
is 1111 1010 0000 0101. The 80mV range has three sign bits.
Only one sign bit needs to be used to calculate the measured
decimal value. Bits 14 and 15 are omitted from the calculation.
This leaves a binary reading of 11 1010 0000 0101.
Next, multiply each bit by its respective weight. Bit0 value would
be multiplied by bit0 weight (1), Bit1 value * Bit1 weight (2),
etc....
Add all the multiplied values to equate to a single number. For
the binary reading 11 1010 0000 0101 this equates to -1531.
The LSB for a shunt register is 10µV. Multiplying the decimal
value by the LSB weight yields the measured voltage across the
shunt. A 1111 1010 0000 0101 reading equals -15.31mV
measured across the shunt pins.
TABLE 7. SHUNT VOLTAGE REGISTER, PG GAIN = /8 (RANGE = 11), FULL SCALE = ±300MV, 15 BITS WIDE
Bit
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
NAME Sign Bit14 Bit13 Bit12 Bit11 Bit10 Bit9 Bit8 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
WEIGHT -32768 16384 8192 4096 2048 1024 512 256 128 64 32 16
8
4
2
1
Bit
NAME
WEIGHT
TABLE 8. SHUNT VOLTAGE REGISTER, PG GAIN = /4 (RANGE = 10), FULL SCALE = ±160MV, 14 BITS WIDE
D15
D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Sign
Sign Bit13 Bit12 Bit11 Bit10 Bit9 Bit8 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
-16384 8192 4096 2048 1024 512 256 128 64 32 16
8
4
2
1
TABLE 9. SHUNT VOLTAGE REGISTER, PG GAIN = /2 (RANGE = 01), FULL SCALE = ±80MV, 13 BITS WIDE
Bit D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
NAME Sign Sign Sign Bit12 Bit11 Bit10 Bit9 Bit8 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
WEIGHT
-8192 4096 2048 1024 512 256 128 64
32
16
8
4
2
1
TABLE 10. SHUNT VOLTAGE REGISTER, PG GAIN = /1 (RANGE = 00), FULL SCALE = ± 40MV, 12 BITS WIDE
Bit D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
NAME Sign Sign Sign Sign Bit11 Bit10 Bit9 Bit8 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
WEIGHT
-4096 2048 1024 512 256 128 64
32
16
8
4
2
1
15
FN8386.1
April 26, 2013