REV.
ADF4001
–7–
ANALOG LOCK DETECT
DIGITAL LOCK DETECT
R COUNTER OUTPUT
N COUNTER OUTPUT
SDOUT
DGND
DVDD
CONTROL
MUXOUT
MUX
Figure 6. MUXOUT Circuit
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
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 k
nominal. When lock has been detected,
this output will be high with narrow low-going pulses.
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
and 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.
Table I. C2, C1 Truth Table
Control Bits
C2
C1
Data Latch
00
R Counter
01
N Counter
10
Function Latch
11
Initialization Latch
Table II. ADF4001 Family Latch Summary
REFERENCE COUNTER LATCH
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
C2 (0) C1 (0)
R1
R2
R3
R4
R5
R7
R14
ABP1
T2
LDP
R13
R6
CONTROL
BITS
ABP2
T1
DB21
R12
R11
R10
DB22
DB23
R8
R9
RESERVED
LOCK
DETECT
PRECISION
TEST
MODE
BITS
ANTI-
BACKLASH
WIDTH
14-BIT REFERENCE COUNTER
XX
X
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
C2 (1) C1 (1)
F1
PD1
M1
M2
M3
F3
CPI1
CPI2
CPI5
CPI6
TC4
PD2
F2
CONTROL
BITS
C
OUNTER
R
ESET
P
OWER-
D
OWN
1
MUXOUT
CONTROL
PHASE
DETECTOR
POLARITY
CP
THREE-
ST
A
T
E
P
OWER-
D
OWN
2
CURRENT
SETTING
1
TIMER COUNTER
CONTROL
CPI3
CPI4
DB21
CURRENT
SETTING
2
TC3
TC2
TC1
DB22
DB23
FA
STLOCK
E
NABLE
FA
S
T
LOCK
M
ODE
F4
F5
RESERVED
X = DON’T CARE
XX
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
C2 (0) C1 (1)
N1
N8
N9
N12
N13
N7
G1
CONTROL
BITS
N10
N11
DB21
N6
N5
N4
DB22
DB23
N2
N3
RESERVED
CP
GAIN
RESERVED
13-BIT N COUNTER
XX
X
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
C2 (1) C1 (0)
F1
PD1
M1
M2
M3
F3
CPI1
CPI2
CPI5
CPI6
TC4
PD2
F2
CONTROL
BITS
C
OUNTER
R
ESET
P
OWER-
D
OWN
1
MUXOUT
CONTROL
PHASE
DETECTOR
POLARITY
CP
THREE-
ST
A
T
E
P
OWER-
D
OWN
2
CURRENT
SETTING
1
TIMER COUNTER
CONTROL
CPI3
CPI4
DB21
CURRENT
SETTING
2
TC3
TC2
TC1
DB22
DB23
FA
STLOCK
E
FA
S
T
LOCK
M
ODE
F4
F5
RESERVED
XX
N COUNTER LATCH
FUNCTION LATCH
INITIALIZATION LATCH
B