M16C User Manual.pdf

A-D ConverterMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTERTable 2.7.11. Variation of the successive comparison register and Vref while A-D conversion is inprogress (10-bit mode)Successive approximation registerVref changeA-D converter stoppedb91b00 0 0 0 0 0 0 0 0VREF2[V]1st comparison2nd comparison3rd comparison1n90100000000000000001st comparison resultn9 n8 1 0 0 0 0 0 0 02nd comparison resultVREF2VREF2VREF2–±±VREF [V]2048VREFn9 = 1 +VREF VREF – [V] VREF4 2048 n9 = 0 –4VREF44n8 = 1 +VREF± –VREF [V]8 2048 n8 = 0 –VREF8VREF810th comparisonn9 n8 n7 n6 n5 n4 n3 n2 n1 0VREF2±VREF4±VREF8VREF± ...... ±1024 – VREF2048[V]Conversion completen9 n8 n7 n6 n5 n4 n3 n2 n1 n0This data transfers to the bit 0to bit 9 of A-D register.Result of A-D conversion3FF163FE1600316002160011600016conversion characteristicTheoretical A-DVREF1024 x 1 VREF1024 x 2 VREF0VREF1024 x 0.51024 x 3 VREF1024x 1021Ideal A-D conversioncharacteristicVREF VREFx 1022 x 1023 VREF1024 1024Analog input voltageFigure 2.7.23. Theoretical A-D conversion characteristics (10-bit mode)406