c8051t617 Silicon Laboratories, c8051t617 Datasheet - Page 114

• Manufacturer Part Number: c8051t617
• Description: Mixed Signal Byte-programmable Eprom Mcu
• Manufacturer: Silicon Laboratories

C8051T610/1/2/3/4/5/6/7
SFR Definition 13.4. OSCXCN: External Oscillator Control
114
Bit7:
Bits6–4: XOSCMD2-0: External Oscillator Mode Bits.
Bit3:
Bits2–0: XFCN2-0: External Oscillator Frequency Control Bits.
RC Mode (Circuit from Figure 13.1, Option 2; XOSCMD = 10x)
Capacitor Mode (Circuit from Figure 13.1, Option 3; XOSCMD = 10x)
Bit7
R
-
Unused. Read = 0b, Write = don’t care.
00x: External Oscillator circuit off.
010: External CMOS Clock Mode.
011: External CMOS Clock Mode with divide by 2 stage.
100: RC Oscillator Mode with divide by 2 stage.
101: Capacitor Oscillator Mode with divide by 2 stage.
11x: Reserved.
Unused. Read = 0b, Write = don't care.
000-111: See table below:
Choose XFCN value to match frequency range:
f = 1.23(10
f = frequency of clock in MHz
C = capacitor value in pF
R = Pullup resistor value in kΩ
Choose K Factor (KF) for the oscillation frequency desired:
f = KF / (C x V
f = frequency of clock in MHz
C = capacitor value the EXTCLK pin in pF
V
XOSCMD2 XOSCMD1 XOSCMD0
DD
= Power Supply on MCU in volts
XFCN
R/W
Bit6
000
001
010
100
101
011
110
111
3
) / (R x C), where
DD
R/W
), where
Bit5
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
f ≤ 25 kHz
R/W
Bit4
Rev. 0.3
Bit3
R
-
XFCN2
R/W
Bit2
C (XOSCMD = 10x)
K Factor = 1590
K Factor = 0.87
K Factor = 180
K Factor = 664
K Factor = 2.6
K Factor = 7.7
K Factor = 22
K Factor = 65
XFCN1
R/W
Bit1
XFCN0
R/W
Bit0
SFR Address:
00000000
Reset Value
0xB1