max5304cuat Maxim Integrated Products, Inc., max5304cuat Datasheet - Page 6

• Manufacturer Part Number: max5304cuat
• Description: Max5304 10-bit Voltage-output Dac In 8-pin ?max
• Manufacturer: Maxim Integrated Products, Inc.

10-Bit Voltage-Output DAC
in 8-Pin µMAX
_____________________Pin Description
The MAX5304 contains a voltage-output digital-to-ana-
log converter (DAC) that is easily addressed using a
simple 3-wire serial interface. Each IC includes a 16-bit
shift register, and has a double-buffered input com-
posed of an input register and a DAC register (see the
Functional Diagram). In addition to the voltage output,
the amplifier’s negative input is available to the user.
The DAC is an inverted R-2R ladder network that con-
verts a digital input (10 data bits plus 3 sub-bits) into an
equivalent analog output voltage in proportion to the
applied reference voltage. Figure 1 shows a simplified
circuit diagram of the DAC.
The reference input accepts positive DC and AC sig-
nals. The voltage at the reference input sets the full-
scale output voltage for the DAC. The reference input
voltage range is 0V to (V
(V
age source, as expressed in the following equation:
where NB is the numeric value of the DAC’s binary
input code (0 to 1023), V
and Gain is the externally set voltage gain.
The impedance at the reference input is code depen-
dent, ranging from a low value of 18kΩ when the DAC
has an input code of 1550 hex, to a high value exceed-
ing several gigohms (leakage currents) with an input
code of 0000 hex. Because the input impedance at the
reference pin is code dependent, load regulation of the
reference source is important.
6
_______________Detailed Description
OUT
PIN
1
2
3
4
5
6
7
8
_______________________________________________________________________________________
) is represented by a digitally programmable volt-
V
OUT
NAME
SCLK
GND
OUT
REF
V
DIN
CS
FB
DD
= (V
REF
DAC Output Voltage
Chip-Select Input. Active low.
Serial-Data Input
Serial-Clock Input
DAC Output Amplifier Feedback
Reference Voltage Input
Ground
Positive Power Supply
· NB / 1024) Gain
DD
REF
- 1.4V). The output voltage
is the reference voltage,
FUNCTION
Reference Inputs
In shutdown mode, the MAX5304’s REF input enters a
high-impedance state with a typical input leakage cur-
rent of 0.001µA.
The reference input capacitance is also code depen-
dent and typically ranges from 15pF (with an input
code of all 0s) to 50pF (at full scale).
The MAX873 +2.5V reference is recommended for use
with the MAX5304.
The MAX5304’s DAC output is internally buffered by a
precision amplifier with a typical slew rate of 0.6V/µs.
Access to the output amplifier’s inverting input provides
the user greater flexibility in output gain setting/signal
conditioning (see the Applications Information section).
With a full-scale transition at the MAX5304 output, the
typical settling time to ±1/2LSB is 10µs when loaded
with 5kΩ in parallel with 100pF (loads less than 2kΩ
degrade performance).
The amplifier’s output dynamic responses and settling
performances are shown in the Typical Operating
Characteristics.
The MAX5304 features a software-programmable shut-
down that reduces supply current to a typical value of
4µA. Writing 111X XXXX XXXX XXXX as the input-con-
trol word puts the device in shutdown mode (Table 1).
Figure 1. Simplified DAC Circuit Diagram
AGND
REF
SHOWN FOR ALL 1s ON DAC
2R
2R
R
2R
R
2R
R
Output Amplifier
Shutdown Mode
2R
MSB
FB
OUT