M37221M4H_15 Datasheet, PDF (53/114 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER with ON-SCREEN DISPLAY CONTROLLER

M37221M4H/M6H/M8H/MAH–XXXSP/FP M37221EASP/FP
8.9 D-A CONVERTER
This microcomputer has 2 D-A converters with 6-bit resolution. D-A
converter block diagram is shown in Figure 8.9.1.
D-A conversion is performed by setting the value in the DA conver-
sion register. The result of D-A conversion is output from the DA pin
by setting “1” to the DA output enable bit of the port P3 output mode
control register (bits 2 and 3 at address 00CD16).
The output analog voltage V is determined with the value n (n: deci-
mal number) in the DA conversion register.
n
V = VCC ✕ ₆₄ (n = 0 to 63)
The DA output does not build in a buffer, so connect an external
buffer when driving a low-impedance load.
Note: Only M37221EASP/FP have a built-in D-A converter.
Data bus
DA1 conversion
register
6 [address 00DE16]
Resistor ladder
DA2 conversion
register
6 [address 00DF16]
Resistor ladder
DA1 output enable bit
P30/A-D5/DA1
DA2 output enable bit
P31/A-D6/DA2
Fig. 8.9.1 D-A converter block diagram
Rev.1.00 Oct 01, 2002 page 51 of 110
REJ03B0134-0100Z