EVAL-AD5570EBZ Analog Devices Inc, EVAL-AD5570EBZ Datasheet - Page 17

• Manufacturer Part Number: EVAL-AD5570EBZ
• Description: 206-10G-01 Board I.c.
• Manufacturer: Analog Devices Inc
• Series: 0040r

Specifications of EVAL-AD5570EBZ

• Number Of Dac's: *
• Number Of Bits: 16
• Outputs And Type: 1, Single Ended
• Sampling Rate (per Second): 83k
• Data Interface: Serial
• Settling Time: 12µs
• Dac Type: *
• Voltage Supply Source: Dual ±
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD5570
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

TRANSFER FUNCTION
Table 6 shows the ideal input code to the output voltage rela-
tionship for the AD5570.
Table 6. Binary Code Table
MSB
1111
1000
1000
0111
0000
The output voltage expression is given by
where:
D is the decimal equivalent of the code loaded to the DAC.
V
CLEAR (CLR)
CLR is an active low digital input that allows the output to be
cleared to 0 V. When the CLR signal is brought back high, the
output stays at 0 V until LDAC is brought low. The relationship
between LDAC and CLR is explained further in
Table 7. Relationships Among PD , CLR , and LDAC
PD
0
1
1
1
1
REFIN
V
CLR
x
0
0
1
1
is the reference voltage available at the REFIN pin.
OUT
1111
0000
0000
1111
0000
Digital Input
=
LDAC
x
0
1
0
1
−
2
V
REFIN
1111
0000
1111
0000
0000
Comments
PD has priority over LDAC and CLR . The
output remains at 0 V through an internal
20 kΩ resistor. It is still possible to address
both the input register and DAC register
when the AD5570 is in power-down.
Data is written to the input register and
DAC register. CLR has higher priority over
LDAC ; therefore, the output is at 0 V.
Data is written to the input register only.
The output is at 0 V and remains at 0 V
when CLR is taken back high.
Data is written to the input register and the
DAC register. The output is driven to the
DAC level.
Data is written to the input register only.
The output of the DAC register is unchanged.
+
4
LSB
1111
0001
1111
0000
×
0000
V
REFIN
[
Analog Output (V
+2 V
+2 V
−2 V
−2 V
0 V
D
/
65536
REF
REF
REF
REF
× (32,767/32,768)
× (1/32,768)
× (1/32,768)
]
Table 7
OUT
.
)
Rev. C | Page 17 of 24
POWER-DOWN ( PD )
The power-down pin allows the user to place the AD5570 into
a power-down mode. In power-down mode, power consump-
tion is at a minimum; the device typically consumes only 16 μA.
POWER-ON RESET
The AD5570 contains a power-on reset circuit that controls the
output during power-up and power-down. This is useful in appli-
cations where the known state of the output of the DAC during
power-up is important. On power-up and power-down, the output
of the DAC and V
SERIAL DATA OUTPUT (SDO)
The SDO is the internal shift registers output. For the AD5570,
SDO is an internal pull-down only; an external pull-up resistor
of ~5 kΩ to external logic high is required. SDO pull-down is
disabled when the device is in power-down, thus saving current.
The availability of SDO allows any number of AD5570s to be
daisy-chained together. It also allows for the contents of the DAC
register, or any number of DACs daisy-chained together, to be
read back for diagnostic purposes.
Daisy Chaining
This mode of operation is designed for multi DAC systems,
where several AD5570s can be connected in cascade as shown
in Figure 38. This is done by connecting the control inputs in
parallel and then daisy-chaining the SDIN and SDO I/Os of
each device. An external pull-up resistor of ~5 kΩ on SDO is
required when using the part in daisy-chain mode.
As described earlier, when SYNC goes low, serial data on SDIN
is shifted into the input shift register on the falling edge of SCLK.
If more than 16 clock pulses are applied, the data ripples out of
the shift resister and appears on the SDO line. By connecting
this line to the SDIN input on the next AD5570 in the chain, a
multi DAC interface can be constructed.
One data transfer cycle of 16 SCLK pulses is required for each
DAC in the system. Therefore, the total number of clock cycles
must equal 16 N, where N is the total number of devices in the
chain. The first data transfer cycle written into the chain appears at
the last DAC in the system on the final data transfer cycle.
When the serial transfer to all devices is complete, take SYNC high.
This prevents any further data from being clocked into the devices.
A continuous SCLK source can be used if SYNC is held low
for the correct number of clock cycles. Alternatively, a burst
clock containing the exact number of clock cycles can be used
and SYNC is taken high some time later. The outputs of all the
DACs in the system can be updated simultaneously using the
LDAC signal.
OUT
, is held at AGND.
AD5570