1.7.6 N COUNTER

The calculated value of N, and the value of P are now used to determine the values of A and B where A and B are both integer

values:

where B is the divisor and A is the remainder. Therefore:

B = div (N/P)

and

For this example, B and A are calculated as follows:

B = div (4750/32) = 148 = 0000010010100

and

To load the N counter with these values, the programming bit stream would be as follows. The first bit, the GO bit, (MSB) N[19]

is used for FastLock operation and will be discussed in the F Latch section. The next 13 bits, (N[18]–N[6]) shifted in, are the B

counter value, 0000010010100

bits) are 1,0 identifying the N counter. In programming the N counter, the value of B must be greater than or equal to A, and the

value of B must be greater than or equal to 3.

Note: *In programming the counter, data is shifted in MSB first.

1.7.7 R COUNTER

Programming the R counter is done by shifting in the binary value of R calculated previously (50

in is R[19] the LD precision bit. The next 4 bits (R[18]–R[15]) shifted in, are used for testing and should always be loaded with

zeros. The R[14]–R[1] bits are used to program the reference divider ratio and should be 00000000110010

final two bits, C[1] and C[2] denote the R counter and should be 0, 0. The resulting bit stream looks as follows:

1.7.8 F LATCH

To program the device for any of the FastLock modes, C[1] = 0 and C[2] = 1 which direct data to the F latch. The Section 1.3

FUNCTION AND INITIALIZATION LATCH section discusses the 4 modes of FastLock operation. The user must first determine

which FastLock mode will be used. When using any of the FastLock modes, the programmer needs to experimentally determine

the length of time to stay in high gain mode. This is done by looking at the transient response and determining the time at which

the device has settled to within the appropriate frequency tolerance. FastLock mode should be terminated just prior to “lock” to

place the switching phase glitch within the transient settling time. The counter reset mode (F[1] bit) holds both the N and R

counters at load point when F[1] = HIGH. Upon setting F[1] = LOW, the N and R counters will resume counting in close phase

alignment. Other functions of the F latch such as FoLD output control, Phase detector polarity, and charge pump TRI-STATE are

defined in the 1.3 FUNCTION AND INITIALIZATION LATCH section also.

DS100127-14

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