ADF4001
DV
DD
25 ns is detected on any subsequent PD cycle. The N-channel
open-drain analog lock detect should be operated with an external
pull-up resistor of 10 kΩ nominal. When lock has been detected,
this output will be high with narrow low-going pulses.
ANALOG LOCK DETECT
DIGITAL LOCK DETECT
INPUT SHIFT REGISTER
The ADF4001 digital section includes a 24-bit input shift regis-
ter, a 14-bit R counter, and a 13-bit N counter. Data is clocked
into the 24-bit shift register on each rising edge of CLK. The
data is clocked in MSB first. Data is transferred from the shift
register to one of four latches on the rising edge of LE. The
destination latch is determined by the state of the two control
bits (C2, C1) in the shift register. These are the two LSBs DB1,
DB0 as shown in the timing diagram of Figure 1. The truth
table for these bits is shown in Table I. Table II shows a sum-
mary of how the latches are programmed.
CONTROL
MUXOUT
MUX
R COUNTER OUTPUT
N COUNTER OUTPUT
SDOUT
DGND
Figure 6. MUXOUT Circuit
Table I. C2, C1 Truth Table
Control Bits
Lock Detect
MUXOUT can be programmed for two types of lock detect:
digital lock detect and analog lock detect. Digital lock detect is
active high. When LDP in the R counter latch is set to “0,” digital
lock detect is set high when the phase error on three consecutive
Phase Detector cycles is less than 15 ns. With LDP set to “1,” five
consecutive cycles of less than 15 ns are required to set the lock
detect. It will stay set high until a phase error of greater than
C2
C1
Data Latch
0
0
1
1
0
1
0
1
R Counter
N Counter
Function Latch
Initialization Latch
Table II. ADF4001 Family Latch Summary
REFERENCE COUNTER LATCH
ANTI-
BACKLASH
WIDTH
TEST
MODE
BITS
CONTROL
BITS
14-BIT REFERENCE COUNTER
RESERVED
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13
DB12 DB11 DB10
DB9
R8
DB8
R7
DB7
R6
DB6 DB5 DB4
R5 R4 R3
DB3
R2
DB2 DB1 DB0
R1 C2 (0) C1 (0)
ABP2
X
X
X
LDP
T2
T1
ABP1 R14
R13
R12
R11
R10
R9
N -COUNTER
CONTROL
BITS
CP
GAIN
13-BIT N COUNTER
RESERVED
RESERVED
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13
DB12 DB11 DB10
DB9
N2
DB8
N1
DB7
DB6 DB5 DB4
DB3
DB2 DB1 DB0
C2 (0) C1 (1)
G1
N13
N12
N11
N10
N9
N8
N7
N6
N5
N4
N3
X
X
FUNCTION LATCH
CURRENT
SETTING
2
CURRENT
SETTING
1
TIMER COUNTER
CONTROL
MUXOUT
CONTROL
CONTROL
BITS
RESERVED
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13
DB12 DB11 DB10
TC2 TC1 F5
DB9
F4
DB8
F3
DB7
F2
DB6 DB5 DB4
DB3
PD1
DB2 DB1 DB0
PD2
CPI6
CPI5
CPI4
CPI3
CPI2
CPI1
TC4
TC3
M3
M2
M1
F1
C2 (1) C1 (0)
X
X
INITIALIZATION LATCH
CURRENT
SETTING
2
CURRENT
SETTING
1
TIMER COUNTER
CONTROL
MUXOUT
CONTROL
CONTROL
BITS
RESERVED
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13
PD2 CPI6 CPI5 CPI4 CPI3 CPI2 CPI1 TC4 TC3
X = DON’T CARE
DB12 DB11 DB10
TC2 TC1 F5
DB9
F4
DB8
F3
DB7
F2
DB6 DB5 DB4
M3 M2 M1
DB3
PD1
DB2 DB1 DB0
F1 C2 (1) C1 (1)
X
X
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