C8051F226-TB Silicon Laboratories Inc, C8051F226-TB Datasheet - Page 99

• Manufacturer Part Number: C8051F226-TB
• Description: BOARD PROTOTYPING W/C8051F226
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F226-TB

• Contents: Board
• Processor To Be Evaluated: C8051F22x and C8051F23x
• Interface Type: USB
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: C8051F226
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Bit7:
Bits6–4: XOSCMD2–0: External Oscillator Mode Bits
Bit3:
Bits2–0: XFCN2–0: External Oscillator Frequency Control Bits
CRYSTAL MODE (Circuit from Figure 13.1, Option 1; XOSCMD = 11x)
RC MODE (Circuit from Figure 13.1, Option 2; XOSCMD = 10x)
C MODE (Circuit from Figure 13.1, Option 3; XOSCMD = 10x)
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
Bit7
R
XFCN
XTLVLD: Crystal Oscillator Valid Flag
(Valid only when XOSCMD = 1xx.)
0: Crystal Oscillator is unused or not yet stable
1: Crystal Oscillator is running and stable
00x: Off. XTAL1 pin is grounded internally.
010: System Clock from External CMOS Clock on XTAL1 pin.
011: System Clock from External CMOS Clock on XTAL1 pin divided by 2.
10x: RC/C Oscillator Mode with divide by 2 stage.
110: Crystal Oscillator Mode
111: Crystal Oscillator Mode with divide by 2 stage.
RESERVED. Read = undefined, Write = don’t care
000–111: see table below
Choose XFCN value to match the crystal frequency. 
Choose oscillation frequency range where:
f = 1.23(10
f = frequency of oscillation in MHz
C = capacitor value in pF
R = Pull-up resistor value in k 
Choose K Factor (KF) for the oscillation frequency desired:
f = KF / (C x AV+) , where
f = frequency of oscillation in MHz
C = capacitor value on XTAL1, XTAL2 pins in pF
V
000
001
010
100
101
011
110
111
DD
SFR Definition 13.2. OSCXCN: External Oscillator Control
R/W
Bit6
= Power supply voltage on MCU in volts
Crystal (XOSCMD = 11x)
2.23 MHz < f  6.74 MHz
30.35 kHz < f  93.8 kHz
12.5 kHz < f  30.3 kHz
722 kHz < f  2.23 MHz
93.8 kHz < f  26 7kHz
267 kHz < f  722 kHz
3
) / (R x C) , where
f > 6.74 MHz
f  12.5 kHz
R/W
Bit5
R/W
Bit4
Rev. 1.6
1.6 MHz < f  3.2 MHz
100 kHz < f  200 kHz
200 kHz < f  400 kHz
400 kHz < f  800 kHz
800 kHz < f  1.6 MHz
RC (XOSCMD = 10x)
50 kHz < f  100 kHz
25 kHz < f  50 kHz
R/W
Bit3
-
f  25 kHz
XFCN2
R/W
Bit2
XFCN1
R/W
Bit1
C (XOSCMD = 10x)
K Factor = 1400
K Factor = 0.44
K Factor = 100
K Factor = 420
K Factor = 1.4
K Factor = 4.4
K Factor = 13
K Factor = 38
C8051F2xx
XFCN0
R/W
Bit0
SFR Address:
Reset Value
00110000
0xB1
99