71M6533 Datasheet, PDF (11/132 Pages) Teridian Semiconductor Corporation – Energy Meter IC

FDS_6533_6534_004
71M6533/G/H and 71M6534/H Data Sheet
Table 1: Signals Selected for the ADC with SLOTn_SEL and SLOTn_ALTSEL (MUX_DIV[3:0] = 7)
Time
Slot
0
1
2
3
4
5
6
Regular Slot
Register
SLOT0_SEL[3:0]
SLOT1_SEL[3:0]
SLOT2_SEL[3:0]
SLOT3_SEL[3:0]
SLOT4_SEL[3:0]
SLOT5_SEL[3:0]
SLOT6_SEL[3:0]
SLOT7_SEL[3:0]
SLOT8_SEL[3:0]
SLOT9_SEL[3:0]
Typical Selections
Signal
Number
0
1
Signal for
ADC
IA
VA
2
IB
3
VB
4
IC
5
VC
6
ID
–
–
–
–
–
–
Alternate Slot
Register
SLOT0_ALTSEL[3:0]
SLOT1_ALTSEL[3:0]
SLOT2_ALTSEL[3:0]
SLOT3_ALTSEL[3:0]
SLOT4_ALTSEL[3:0]
SLOT5_ALTSEL[3:0]
SLOT6_ALTSEL[3:0]
SLOT7_ALTSEL[3:0]
SLOT8_ALTSEL[3:0]
SLOT9_ALTSEL[3:0]
Typical Selections
Signal
Number
A
1
B
3
4
Signal for
ADC
TEMP
VA
VBAT
VB
IC
5
VC
6
ID
The duration of each multiplexer state depends on the number of ADC samples processed by the FIR,
which is set by FIR_LEN[1:0]. Each multiplexer state will start on the rising edge of CK32. FIR conversions
require 1, 2, or 3 CK32 cycles. The number of CK32 cycles is determined by FIR_LEN[1:0].
1.2.3 A/D Converter (ADC)
A single delta-sigma A/D converter digitizes the voltage and current inputs to the 71M6533/71M6534. The
resolution of the ADC is programmable using the I/O RAM bits M40MHZ and M26MHZ (see Table 2). The
CE code must be tailored for use with the selected ADC resolution.
Table 2: ADC Resolution
Setting for [M40MHZ,
M26MHZ]
[00], [10] or [11]
[01]
FIR_LEN[1:0]
0
1
2
0
1
2
FIR CE
Cycles
138
288
384
186
384
588
Resolution
18 bits
21 bits
22 bits
19 bits
22 bits
24 bits
Initiation of each ADC conversion is controlled by MUX_CTRL as described in Section 1.1.1. At the end of
each ADC conversion, the FIR filter output data is stored into the CE RAM location determined by the MUX
selection.
1.2.4 FIR Filter
The finite impulse response filter is an integral part of the ADC and it is optimized for use with the multiplexer.
The purpose of the FIR filter is to decimate the ADC output to the desired resolution. At the end of each
ADC conversion, the output data is stored into the fixed CE RAM location determined by the multiplexer
selection as shown in Table 3. FIR data is stored LSB justified, but shifted left by eight bits.
Rev 2
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