M16C28 Datasheet, PDF (268/423 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/Tiny SERIES

M16C/28 Group (M16C/28, M16C/28B)
15. A/D Converter
15.2 Resolution Select Function
The BITS bit in the ADCON1 register determines the resolution. When the BITS bit is set to “1” (10-bit
precision), the A/D conversion result is stored into bits 0 to 9 in the ADi register (i=0 to 7). When the BITS
bit is set to “0” (8-bit precision), the A/D conversion result is stored into bits 0 to 7 in the ADi register.
15.3 Sample and Hold
When the SMP bit in the ADCON 2 register is set to “1” (with the sample and hold function), A/D conver-
sion rate per pin increases to 28 φAD cycles for 8-bit resolution or 33 φAD cycles for 10-bit resolution. The
sample and hold function is available in one-shot mode, repeat mode, single sweep mode, repeat sweep
mode 0 and repeat sweep mode 1. In these modes, start A/D conversion after selecting whether the
sample and hold circuit is to be used or not. In simultaneous sample sweep mode, delayed trigger mode
0 or delayed trigger mode , set to use the Sample and Hold function before starting A/D conversion.
15.4 Power Consumption Reducing Function
When the A/D converter is not used, the VCUT bit in the ADCON1 register isolates the resistor ladder of
the A/D converter from the reference voltage input pin (VREF). Power consumption is reduced by shutting
off any current flow into the resistor ladder from the VREF pin.
When using the A/D converter, set the VCUT bit to “1” (Vref connected) before setting the ADST bit in the
ADCON0 register to “1” (A/D conversion started). Do not set the ADST bit and VCUT bit to “1” simulta-
neously, nor set the VCUT bit to “0” (Vref unconnected) during A/D conversion.
Rev. 2.00 Jan. 31, 2007 ^{page 248} of 385
REJ09B0047-0200