LMX2326TM National Semiconductor, LMX2326TM Datasheet - Page 16

• Manufacturer Part Number: LMX2326TM
• Manufacturer: National Semiconductor
• Type: PLL Frequency Synthesizerr

Specifications of LMX2326TM

• Number Of Elements: 1
• Supply Current: 7mA
• Pll Input Freq (min): 100MHz
• Pll Input Freq (max): 2.8GHz
• Operating Supply Voltage (typ): 3V
• Operating Temp Range: -40C to 85C
• Package Type: TSSOP
• Operating Supply Voltage (min): 2.3V
• Operating Supply Voltage (max): 5.5V
• Operating Temperature Classification: Industrial
• Pin Count: 16
• Lead Free Status / Rohs Status: Not Compliant

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2.0 Application Information
2.6 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:
For this example, B and A are calculated as follows:
2.7 R COUNTER
Programming the R counter is done by shifting in the binary
value of R calculated previously (50
shifted in is R[19] the LD precision bit. The next 4 bits
(R[18]–R[15]) shifted in, are used for testing and should
2.8 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 dis-
cusses 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
(Continued)
A = N − (B * P)
N = P * B + A
B = div (N/P)
and
d
= 110010
b
). The first bit
16
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
are the A counter and are 01110
two bits (the control 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.
always be loaded with zeros. The R[14]–R[1] bits are used to
program the reference divider ratio and should be
00000000110010
and C[2] denote the R counter and should be 0, 0. The
resulting bit stream looks as follows:
within the appropriate frequency tolerance. FastLock mode
should be terminated just prior to “lock” to place the switch-
ing 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.
B = div (4750/32) = 148 = 0000010010100
A = 4750 − (148 * 32) = 14 = 01110
b
for this example. The final two bits, C[1]
and
b
in this example. The final
10012714
10012716
b
*. Bits N[5]–N[1]