ES51963
4 1/2 DMM
(8) PEAK Hold
During PEAK hold mode, ES51963 will charge the two external capacitors, PMAX and
PMIN, to follow the maximum and minimum input voltages. ES51963 performs A-to-D with
input from PMAX and PMIN alternately and outputs the result to the microprocessor. It is
important that the microprocessor must keep the maximum and minimum values by itself since
ES51963 does not keep the peak value. In addition, as the internal OPs have offset the user must
enter peak hold calibration mode to catch the offset values. As similar to zero calibration, the
offset error can be eliminated by subtracting the stored valued from subsequent measurements.
The detail timing for peak hold operation is as follow:
Operation on Format 1:
PEAK Hold calibration at format 1:
In calibration mode, the Pmax and Pmin are measured two times alternately, then the
microprocessor can catch the last offset voltage (Vos) of Pmax and Pmin.
(V-)+2.1V
(V-)+0.8V
SCLK
END
START
set Pcal (S6) to H
(V-)+2.1V
(V-)+0.8V
calibration
EOC
(V-)+2.1V
(V-)+0.8V
Pmax
Vos
Pmin
Vos
Pmax
Vos
Pmin
Vos
MODE 2 (uP to A/D)
MODE 1 (A/D to uP)
Note: it is not necessary to set PEAK (S5) to H at the same time.
To active PEAK Hold after calibration at format 1:
(V-)+2.1V
(V-)+0.8V
SCLK
START
END
set PEAK (S5) to H
(V-)+2.1V
(V-)+0.8V
PEAK Hold
EOC
(V-)+2.1V
(V-)+0.8V
Pmax
Pmin
MODE 1 (A/D to uP)
Pmax
Pmin
MODE 2 (uP to A/D)
To cancel PEAK Hold function at format 1:
15
2003/9/1
CYRUSTEK [ Cyrustek corporation ]
