ES51998(60000counts)
DMM Analog front end/Insulation
2.10 Peak-hold measurement mode
ES51998 provides a peak hold function to capture the real peak value for voltage or current
measurement mode. In a case of a 1V sine wave input voltage, the peak hold function gets a
maximum peak value of 1.414V and minimum peak value of –1.414V ideally. Set the
control bit PEAK=1 to force the ES51998 entering PEAK measurement mode. Peak Hold
function is divided into two parts of peak maximum and peak minimum conversion. High
resolution SADC performs peak maximum and peak minimum conversion in turn, not at the
same time. The status flag PMAX or PMIN shows which type the peak value is. If
PMAX=1(PMIN=1), the SADC output D0 is the conversion data on PMAX (PMIN)
terminals (pin 61/62). The MPU should make the comparison procedure to get the
maximum value of PMAX data and minimum value of PMIN data. The max counts for D0
is 103000.
Peak calibration mode
At PEAK-Hold measurement mode, the offset voltage of internal operation amplifier will
cause an error. To obtain a more accurate value, the offset error must be canceled. ES51998
provides the peak calibration feature to remove the influence on accuracy by internal offset
voltage. Set the control bit PCAL=1 to enter peak calibration mode. When PCAL mode is
active, the SADC of ES51998 will output the calibration value of peak maximum and
minimum conversion in turn. The offset values should be memorized respectively and
deducted from the data of PMAX/PMIN at the normal peak measurement mode.
Set PCAL=1 or PEAK=1
Status indication
ADC data
PMAX=1, PMIN=0 PMAX=0, PMIN=1
VPMAX.C VPMIN.C
VPMAX.C and VPMIN.C are not the real-time value of peak-hold voltage. They are the voltage
stored on terminal capacitor (pin61-62). Because the capacitor will be self-discharging, so
MCU need to compare the VPMAX.C & VPMIN.C respectively and memorize the maximum and
minimum peak values in turn.
ver. 1.7
23
12/01/12
CYRUSTEK [ Cyrustek corporation ]
