Datasheet

AD9640
Rev. B | Page 46 of 52
Addr
(Hex)
Register
Name
Bit 7
(MSB)
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1
Bit 0
(LSB)
Default
Value
(Hex)
Default
Notes/
Comments
0x11A
Signal Monitor
Result
Channel B
Register 1
(Global)
Signal Monitor Result Channel B[15:8] Read only
0x11B
Signal Monitor
Result
Channel B
Register 2
(Global)
Open Open Open Open Signal Monitor Result Channel B[19:16] Read only
MEMORY MAP REGISTER DESCRIPTION
For additional information about functions controlled in
Register 0x00 to Register 0xFF, see the AN-877 Application Note,
Interfacing to High Speed ADCs via SPI.
Sync Control (Register 0x100)
Bit 7—Signal Monitor Sync Enable
Bit 7 enables the sync pulse from the external SYNC input to
the signal monitor block. The sync signal is passed when Bit 7
is high and Bit 0 is high. This is continuous sync mode.
Bits[6:3]—Reserved
Bit 2—Clock Divider Next Sync Only
If the sync enable bit (Address 0x100[0]) is high and the clock
divider sync enable (Address 0x100[1]) is high, Bit 2 allows the
clock divider to sync to the first sync pulse it receives and ignore
the rest. Address 0x100[1] resets after it syncs.
Bit 1—Clock Divider Sync Enable
Bit 1 gates the sync pulse to the clock divider. The sync signal is
passed when Bit 1 is high and Bit 0 is high. This is continuous
sync mode.
Bit 0—Master Sync Enable
Bit 0 must be high to enable any of the sync functions.
Fast Detect Control (Register 0x104)
Bits[7:4]—Reserved
Bits[3:1]—Fast Detect Mode Select
These bits set the mode of the fast detect output bits according
to Table 17.
Bit 0—Fast Detect Enable
Bit 0 is used to enable the fast detect bits. When the fast detect
outputs are disabled, the outputs go into a high impedance state.
In LVDS mode, when the outputs are interleaved, the outputs go
high-Z only if both channels are turned off (power-down/standby/
output disabled). If only one channel is turned off (power-down/
standby/output disabled), the fast detect outputs repeat the data
of the active channel.
Fine Upper Threshold (Register 0x106 and Register 0x107)
Register 0x106, Bits[7:0]—Fine Upper Threshold[7:0]
Register 0x107, Bits[7:5]—Reserved
Register 0x107, Bits[4:0]—Fine Upper Threshold[12:8]
These registers provide the fine upper limit threshold. This 13-bit
value is compared to the 13-bit magnitude from the ADC block
and, if the ADC magnitude exceeds this threshold value, the
F_UT flag is set.
Fine Lower Threshold (Register 0x108 and Register 0x109)
Register 0x108, Bits[7:0]—Fine Lower Threshold[7:0]
Register 0x109, Bits[7:5]—Reserved
Register 0x109, Bits[4:0]—Fine Lower Threshold[12:8]
These registers provide a fine lower limit threshold. This 13-bit
value is compared to the 13-bit magnitude from the ADC block
and, if the ADC magnitude is less than this threshold value, the
F_LT flag is set.
Signal Monitor DC Correction Control (Register 0x10C)
Bit 7—Reserved
Bit 6—DC Correction Freeze
When Bit 6 is set high, the dc correction is no longer updated
to the signal monitoring block. It holds the last dc value it
calculated.
Bits[5:2]—DC Correction Bandwidth
These bits set the averaging time of the signal monitor dc correc-
tion function. It is a 4-bit word that sets the bandwidth of the
correction block (see Table 26).