User guide

Arch Meter Corporation PS1000 Ver1.2
PS1000Rev. 1.2 May 2006
23/ 67
www.archmeter.com
6.2 AGC
The DSP circuit has built-in one AGC control circuit. It can control the AGC at the
front of IA/IB ADC input. The control range is 1X, 2X, 4X and 8X.
AGCCFG(0xFE20h)
B7 B6 B5 B4 B3 B2 B1 B0
EN MC x TM0 IBGain IAGain
EN: AGC Enable
0: Disable (Used DSP setting)
1: Enable (auto Control)
MC: Multi-Cycle Enable
0: Disable
1: Enable
TM0: ADC Test Mode Control
1: Bypass ADC Anti-Alias Filter for All ADC
IBGain: IB channel gain setting
00: 1X
01: 2X
10: 4X
11: 8X
IAGain: IA channel gain seting
00: 1X
01: 2X
10: 4X
11: 8X
For the auto gain control, it will depend on the integration result of IA and IB. the
default value is 4X. When the IA/IB integration is over the 50% of full scale, the AGC
will decrease the gain value as one level (8X – 4X – 2X – 1X). On the other hand, when
the IA/IB integration value is under the 16% of full scale, AGC will increase the gain
range as one level (1X – 2X – 4X – 8X). When the AGC reach to maximum gain range
(8X), AGC will not increase the gain range again. Similarly, when AGC reach to
minimum gain range (1X), AGC will not decrease the gain range again.