MAX5222EKA+T Maxim Integrated Products, MAX5222EKA+T Datasheet - Page 7

• Manufacturer Part Number: MAX5222EKA+T
• Description: IC DAC 8BIT DUAL BUFF SOT23-8
• Manufacturer: Maxim Integrated Products

Specifications of MAX5222EKA+T

• Settling Time: 10µs
• Number Of Bits: 8
• Data Interface: Serial
• Number Of Converters: 2
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-8
• Resolution: 8 bit
• Interface Type: Serial (SPI)
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Voltage Reference: External
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power Dissipation (max): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: MAX5222EKA+T

The MAX5222 contains two 8-bit, voltage-output DACs.
The DACs are “inverted” R-2R ladder networks using
complementary switches that convert 8-bit digital
inputs into equivalent analog output voltages in propor-
tion to the applied reference voltage.
The MAX5222 has one reference input that is shared
by DAC A and DAC B. The device includes output
buffer amplifiers for both DACs and input logic for sim-
ple microprocessor (µP) and CMOS interfaces. The
power-supply range is from +5.5V down to +2.7V.
The voltage at REF sets the full-scale output of the
DACs. The input impedance of the REF input is code
dependent. The lowest value, approximately 8kΩ,
occurs when the input code is 01010101 (55hex). The
maximum value of infinity occurs when the input code
is zero.
In shutdown mode, the selected DAC output is set to
zero, while the value stored in the DAC register remains
unchanged. This removes the load from the reference
input to save power. Bringing the MAX5222 out of shut-
down mode restores the DAC output voltage. Because
the input resistance at REF is code dependent, the
DAC’s reference source should have an output imped-
ance of no more than 5Ω. The input capacitance at the
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
______________________________________________________________Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
OUTA
OUTB
SCLK
GND
V
REF
DIN
–
C
Reference Input and DAC Output Range
—
DD
S
–
_______________________________________________________________________________________
Detailed Description
Chip Select, Active Low. Enables data to be shifted into the 16-bit shift register. Programming commands
are executed at the rising edge of
Ground
Positive Power Supply (+2.7V to +5.5V). Bypass with 0.22µF to GND.
Serial Clock Input. Data is clocked in on the rising edge of SCLK.
DAC A Output Voltage (Buffered)
DAC B Output Voltage (Buffered)
Reference Input for DAC A and DAC B
Serial Data Input of the 16-bit Shift Register. Data is clocked into the register on the rising edge of SCLK.
Analog Section
Dual, 8-Bit, Voltage-Output
–
C
Serial DAC in 8-Pin SOT23
—
S
–
.
REF pin is also code dependent and typically does not
exceed 25pF.
The reference voltage on REF can range anywhere from
GND to V
more information.
Figure 1 is the DAC simplified circuit diagram.
DAC A and DAC B voltage outputs are internally
buffered. The buffer amplifiers have a Rail-to-Rail
(GND to V
Both DAC output amplifiers can source and sink up to
1mA of current. See the INL vs. Digital Code graph in
the Typical Operating Characteristics. The amplifiers
are unity-gain stable with a capacitive load of 100pF or
smaller. The slew rate is typically 1V/µs.
When programmed to shutdown mode, the outputs of
DAC A and DAC B are passively pulled to GND with a
series 5kΩ resistor. In shutdown mode, the REF input is
high impedance (2MΩ typical) to conserve current
drain from the system reference; therefore, the system
reference does not have to be powered down.
Coming out of shutdown, the DAC outputs return to the
values kept in the registers. The recovery time is equiv-
alent to the DAC settling time.
FUNCTION
DD
DD
. See the Output Buffer Amplifier section for
) output voltage range.
Output Buffer Amplifiers
Shutdown Mode
®
7