Datasheet

MCP2221

DS20005292A-page 8  2014 Microchip Technology Inc.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

— — — CLKDC1 CLKDC0 CLKDIV2 CLKDIV1 CLKDIV0

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-5 Reserved: Set to ‘0’

bit 4-3 CLKDC<1:0>: Clock-Out Duty-Cycle

11 = Duty cycle 75% (75% of 1 clock period is logic ‘1’ and 25% of 1 clock period is logic ‘0’)

10 = Duty cycle 50% (50% of 1 clock period is logic ‘1’ and 50% of 1 clock period is logic ‘0’)

(factory default)

01 = Duty cycle 25% (25% of 1 clock period is logic ‘1’ and 75% of 1 clock period is logic ‘0’)

00 = Duty cycle 0% (100% of 1 clock period is logic ‘0’)

bit 2-0 CLKDIV<2:0>: Clock-Out Divider Output

111 = 375 kHz clock output

110 = 750 kHz clock output

101 = 1.5 MHz clock output

100 = 3 MHz clock output

011 = 6 MHz clock output

010 = 12 MHz clock output (factory default)

001 = 24 MHz clock output

000 = Reserved

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

DACVRM1 DACVRM0 DACREF DACVAL4 DACVAL3 DACVAL2 DACVAL1 DACVAL0

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-6 DACVRM<1:0>: DAC Internal Voltage Reference (DAC VRM) Selection

11 = VRM voltage is 4.096V (only if V

DD is above this voltage)

10 = VRM voltage is 2.048V (factory default)

01 = VRM voltage is 1.024V

00 = VRM is off

bit 5 DACREF: DAC Reference Output Selection

1 = DAC reference output is DAC VRM voltage selection

0 = DAC reference output is VDD (factory default)

bit 4-0 DACVAL<4:0>: Initial DAC Output Value

5-bit value for the DAC output (factory default is 8 decimal)