68HC908RF datasheet(67/188 Pages) MOTOROLA

67 / 188 page

Internal Clock Generator Module (ICG)

Functional Description

MC68HC908RF2 — Rev. 4.0

Data Sheet

MOTOROLA

Internal Clock Generator Module (ICG)

6.3.1 Clock Enable Circuit

The clock enable circuit is used to enable the internal clock (ICLK) or external clock

(ECLK). The clock enable circuit generates an ICG stop (ICGSTOP) signal which

stops all clocks (ICLK, ECLK, and the low-frequency base clock, IBASE) low.

ICGSTOP is set and the ICG is disabled in stop mode.

The internal clock enable signal (ICGEN) turns on the internal clock generator

which generates ICLK. ICGEN is set (active) whenever the ICGON bit is set and

the ICGSTOP signal is clear. When ICGEN is clear, ICLK and IBASE are both low.

The external clock enable signal (ECGEN) turns on the external clock generator

which generates ECLK. ECGEN is set (active) whenever the ECGON bit is set and

the ICGSTOP signal is clear. When ECGEN is clear, ECLK is low.

6.3.2 Internal Clock Generator

The internal clock generator, shown in Figure 6-2, creates a low-frequency base

clock (IBASE), which operates at a nominal frequency (fNOM) of 307.2 kHz ±25

percent, and an internal clock (ICLK) which is an integer multiple of IBASE. This

multiple is the ICG multiplier factor (N), which is programmed in the ICG multiplier

(IBASE and ICLK) are held low when the internal clock generator enable signal

(ICGEN) is clear.

Figure 6-2. Internal Clock Generator Block Diagram

DIGITALLY

CONTROLLED

OSCILLATOR

ICLK

MODULO

DIVIDER

FREQUENCY

COMPARATOR

CLOCK GENERATOR

TRIM[7:0]

VOLTAGE &

CURRENT

REFERENCES

DIGITAL

LOOP

FILTER

–

– –

N[6:0]

DSTG[7:0]

ICGEN

IBASE

DDIV[3:0]

NAME

MODULE SIGNAL

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

68HC908RF Datasheet(PDF) 67 Page - Motorola, Inc

68HC908RF Datasheet(HTML) 67 Page - Motorola, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL