IC 20-BIT MONOLITHIC D/A 16-QSOP

DAC1220E

Manufacturer Part NumberDAC1220E
DescriptionIC 20-BIT MONOLITHIC D/A 16-QSOP
ManufacturerTexas Instruments
DAC1220E datasheet
 


Specifications of DAC1220E

Settling Time1.8msNumber Of Bits20
Data InterfaceSerialNumber Of Converters1
Voltage Supply SourceAnalog and DigitalPower Dissipation (max)3.5mW
Operating Temperature-40°C ~ 85°CMounting TypeSurface Mount
Package / Case16-QSOPResolution20 bit
Interface TypeSerial (2-Wire, 3-Wire, SPI)Supply Voltage (max)5.25 V
Supply Voltage (min)4.75 VMaximum Operating Temperature+ 85 C
Mounting StyleSMD/SMTMinimum Operating Temperature- 40 C
For Use With296-17265 - MODULE EVALUATION FOR DAC1220Lead Free Status / RoHS StatusLead free / RoHS Compliant
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Output
The output voltage range is nominally 0V to 2 × V
It does not go below ground. The output amplifier is
not designed for heavy loads; it can drive a maximum
of 0.5mA. At power-on and during sleep mode, the
amplifier is disconnected, so the output is high
impedance.
The output is not fully linear to the rails; maximum
linearity is specified from (AGND + 20mV) to (AV
20mV). For linearity from 0–5V, AV
increased to 5.02V or more, and AGND can be
decreased to –20mV or less. As long as the specified
operating limits are observed, this will not damage
the device.
Filter Capacitors
The continuous-time output filter requires two external
capacitors to operate. The recommended values of
these capacitors depend on whether the DAC1220
will be operated in 16-bit or 20-bit mode, and are
shown in
Table
1.
Table 1. Filter Capacitor Values
CAPACITOR
16-BIT MODE
C
2.2nF
1
C
0.22nF
2
The capacitors should be stable and high grade. Film
types, or other capacitors designed for precision
filtering, are strongly recommended. Low-quality
capacitors will degrade performance significantly.
The C
and C
pins are very sensitive. It is critical to
1
2
surround them with a guard ring at the reference
voltage for best noise performance. See the
section for more information.
Voltage Reference
The voltage reference input is designed for +2.5V. At
this voltage, the output will range from ground to
approximately 5V, as noted above.
Copyright © 1998–2009, Texas Instruments Incorporated
SBAS082G – FEBRUARY 1998 – REVISED SEPTEMBER 2009
Digital Connections
.
The digital lines, except for the crystal oscillator lines,
REF
operate at TTL-compatible CMOS logic levels. They
can be driven from 3.3V logic sources.
In noise-sensitive applications, it may be helpful to
keep the level transition rates on the digital lines
slow. Fast transitions can couple through the device
to the output, causing noise. Rate limiting can be
done with resistance or even an RC filter.
DD
can be
DD
Clock Oscillator
The DAC1220 has a built-in crystal oscillator at pins
X
and X
. To use it, connect a crystal and load
IN
OUT
capacitors as shown in
12pF load capacitors are shown in the schematic, but
the correct value depends mainly on the crystal and
layout, and not on the oscillator itself. Load
capacitance
frequency, and reliability. If startup is unreliable, try
lowering the capacitor values. Remember that
parasitic board and pin capacitance can be a
significant portion of the crystal load capacitance.
When the crystal oscillator is operating, a sinusoidal
20-BIT MODE
signal of relatively low amplitude will be observed at
10nF
both the X
and X
IN
3.3nF
The typical frequency to use with the DAC1220 is
2.5MHz. Deviating too far from this may alter noise
and settling time, as well as timing characteristics.
Connecting an External Clock
An external clock signal can be connected at X
CMOS or TTL logic signal can be used. If an external
Layout
clock signal is used, X
In some cases, an RC filter on the clock line may
reduce noise.
Product Folder Link(s):
DAC1220
DAC1220
Figure
5.
affects
startup
time,
oscillation
pins.
OUT
. A
IN
should be left unconnected.
OUT
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