Datasheet

AD9776A/AD9778A/AD9779A
Rev. B | Page 52 of 56
0
0
250
f
DATA
(MSPS)
POWER (W)
0.125
25 50 75 100 125 150 175 200 225
2× INTERPOLATION
4× INTERPOLATION
1× INTERPOLATION,
NO MODULATION
8× INTERPOLATION, f
DAC
/8,
f
DAC
/4,
f
DAC
/2,
NO MODULATION
0.100
0.075
0.050
0.025
06452-082
Figure 97. Power Dissipation, Clock 1.8 V Supply, I and Q Data, Dual DAC
Mode, Does Not Include Zero Stuffing
0
0
250
f
DATA
(MSPS)
POWER (W)
0.075
25 50 75 100 125 150 175 200 225
0.050
0.025
ALL INTERPOLATION MODES
06452-083
Figure 98. Power Dissipation, Digital 3.3 V Supply, I and Q Data,
Dual DAC Mode
0.16
0
0
1200
f
DAC
(MSPS)
POWER (W)
0.14
0.12
0.10
0.08
0.06
0.04
0.02
200 400 600 800 1000
06452-084
Figure 99. DVDD18 Power Dissipation of Inverse Sinc Filter
POWER-DOWN AND SLEEP MODES
The AD9776A/AD9778A/AD9779A have a variety of power-down
modes; thus, the digital engine, main TxDACs, or auxiliary DACs
can be powered down individually or together. Via the 3-wire
interface port, the main TxDACs can be placed in sleep or power-
down mode. In sleep mode, the TxDAC output is turned off,
thus reducing power dissipation. The reference remains powered
on, however, so that recovery from sleep mode is very fast. With
the power-down mode bit set (Register 0x00, Bit 4), all analog
and digital circuitry, including the reference, is powered down.
The 3-wire interface port remains active in this mode. This
mode offers more substantial power savings than sleep mode,
but the turn-on time is much longer. The auxiliary DACs also
have the capability to be programmed into sleep mode via the
3-wire interface port. The auto power-down enable bit (Register
0x00, Bit 3) controls the power-down function for the digital
section of the devices. The auto power-down function works in
conjunction with the TXENABLE pin (Pin 39); see Table 31 for
details.
Table 31.
TXENABLE
(Pin 39) Description
0
If auto power-down enable bit = 0, flush data
path with 0s.
If auto power-down enable bit = 1, flush data for
multiple REFCLK cycles; then, automatically
place the digital engine in power-down state.
DACs, reference, and 3-wire interface port are
not affected.
1 Normal operation.