Information

PIC18(L)F24/25/45K50
DS80000547B-page 6  2012-2013 Microchip Technology Inc.
TABLE 3-6: CLOCK FOR LOW-SPEED USB
System Clock CPUDIV<1:0> Microcontroller Clock LS48MHZ USB Clock
48 11 48/6 = 8 MHz 1 48/8 = 6 MHz
48 10 48/3 = 16 MHz 1 48/8 = 6 MHz
48 01 48/2 = 24 MHz 1 48/8 = 6 MHz
48 00 48 MHz 1 48/8 = 6 MHz
24 11 24/6 = 4 MHz 0 24/4 = 6 MHz
24 10 24/3 = 8 MHz 0 24/4 = 6 MHz
24 01 24/2 = 12 MHz 0 24/4 = 6 MHz
24 00 24 MHz 0 24/4 = 6 MHz
TABLE 3-7: OSCILLATOR CONFIGURATION OPTIONS FOR USB OPERATION
Input Oscillator
Frequency
Clock Mode
(FOSC<3:0>)
MCU Clock Division
(CPUDIV<1:0>)
Microcontroller
Clock Frequency
48 MHz
EC
6 (11)6MHz
3 (10)12MHz
2 (01)24MHz
None (00)48MHz
16 MHz
EC, HS or INTOSC with
3xPLL
 (11)6MHz
3 (10)12MHz
2 (01)24MHz
None (00)48MHz
12 MHz EC or HS with 4xPLL
 (11)6MHz
3 (10)12MHz
2 (01)24MHz
None (00)48MHz
24 MHz EC or HS
(1)
 (11)4MHz
3 (10)8MHz
2 (01)12MHz
None (00)24MHz
Note 1: The 24 MHz mode (without PLL) is only compatible with low-speed USB. Full-speed USB requires a
48 MHz system clock.