General Description
The MAX541/MAX542 are serial-input, voltage-output,
16-bit digital-to-analog converters (DACs) that operate
from a single +5V supply. They provide 16-bit performance (±1LSB INL and DNL) over temperature without
any adjustments. The DAC output is unbuffered, resulting in a low supply current of 0.3mA and a low offset
error of 1LSB.
The DAC output range is 0V to V
REF
. For bipolar operation, matched scaling resistors are provided in the
MAX542 for use with an external precision op amp
(such as the MAX400), generating a ±V
REF
output
swing. The MAX542 also includes Kelvin-sense connections for the reference and analog ground pins to
reduce layout sensitivity.
A 16-bit serial word is used to load data into the DAC
latch. The 10MHz, 3-wire serial interface is compatible
with SPI™/QSPI™/MICROWIRE™, and it also interfaces
directly with optocouplers for applications requiring isolation. A power-on reset circuit clears the DAC output to 0V
(unipolar mode) when power is initially applied.
The MAX541 is available in 8-pin plastic DIP and SO
packages. The MAX542 is available in 14-pin plastic
DIP and SO packages.
Applications
High-Resolution Offset and Gain Adjustment
Industrial Process Control
Automated Test Equipment
Data-Acquisition Systems
Features
♦ Full 16-Bit Performance Without Adjustments
♦ +5V Single-Supply Operation
♦ Low Power: 1.5mW
♦ 1µs Settling Time
♦ Unbuffered Voltage Output Directly Drives 60kΩ
Loads
♦ SPI/QSPI/MICROWIRE-Compatible Serial Interface
♦ Power-On Reset Circuit Clears DAC Output to 0V
(unipolar mode)
♦ Schmitt Trigger Inputs for Direct Optocoupler
Interface
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
________________________________________________________________ Maxim Integrated Products 1
14
13
12
11
10
9
8
1
2
3
4
5
6
7
V
DD
INV
DGND
LDAC
AGNDS
AGNDF
OUT
RFB
TOP VIEW
MAX542
DIN
N.C.
SCLK
CS
REFF
REFS
DIP/SO
DIN
REF
SCLK
CS
1
2
8
7
V
DD
DGND
AGND
OUT
MAX541
3
4
6
5
DIP/SO
General Description
16-BIT DAC
16-BIT DATA LATCH
SERIAL INPUT REGISTER
CONTROL
LOGIC
MAX542
REFF
REFS
CS
LDAC
DIN
SCLK
AGNDS
AGNDF
OUT
INV
RFB
V
DD
DGND
R
FB
R
INV
Functional Diagrams
19-1082; Rev 2; 12/99
PART
MAX541ACPA
MAX541BCPA
MAX541ACSA 0°C to +70°C
0°C to +70°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
8 Plastic DIP
8 Plastic DIP
8 SO
Ordering Information
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
MAX541BCSA 0°C to +70°C 8 SO
INL
(LSB)
±1
±2
±1
±2
Ordering Information continued at end of data sheet.
MAX541CCPA 0°C to +70°C 8 Plastic DIP ±4
MAX541CCSA 0°C to +70°C 8 SO ±4
Functional Diagrams continued at end of data sheet.
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD= +5V ±5%, V
REF
= +2.5V, AGND = DGND = 0, TA= T
MIN
to T
MAX
, unless otherwise noted.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VDDto DGND ...........................................................-0.3V to +6V
CS, SCLK, DIN, LDAC to DGND ..............................-0.3V to +6V
REF, REFF, REFS to AGND ........................-0.3V to (V
DD
+ 0.3V)
AGND, AGNDF, AGNDS to DGND........................-0.3V to +0.3V
OUT, INV to AGND, DGND ......................................-0.3V to V
DD
RFB to AGND, DGND..................................................-6V to +6V
Maximum Current into Any Pin............................................50mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) .....727mW
8-Pin SO (derate 5.88mW/°C above +70°C) .................471mW
14-Pin Plastic DIP (derate 10.00mW/°C above +70°C) ...800mW
14-Pin SO (derate 8.33mW/°C above +70°C) ...............667mW
14-Pin Ceramic SB (derate 10.00mW/°C above +70°C ..800mW
Operating Temperature Ranges
MAX541 _C_ A/MAX542_C_D. .............................0°C to +70°C
MAX541 _E_ A/MAX542_E_D............................-40°C to +85°C
MAX542CMJD .................................................-55°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
MAX542, bipolar mode
Unipolar mode
(Note 3)
4.75V ≤ VDD≤ 5.25V
MAX542
TA= T
MIN
to T
MAX
TA= +25°C
Ratio error
TA= +25°C
TA= T
MIN
to T
MAX
VDD= 5V
TA= +25°C
RFB/R
INV
TA= T
MIN
to T
MAX
(Note 2)
CONDITIONS
kΩ
9.0
R
REF
Reference Input Resistance
(Note 4)
11.5
V2.0 3.0V
REF
Reference Input Range
PSRPower-Supply Rejection LSB±1.0
ppm/°C±0.5BZS
TC
Bipolar Zero Tempco
LSB
±10
±0.015
Bipolar Resistor Matching
1.0
R
OUT
DAC Output Resistance kΩ6.25
±0.5 ±1.0
Bits16NResolution
ppm/°C±0.1Gain-Error Tempco
LSB
±10
Gain Error (Note 1)
±5
ppm/°C±0.05ZS
TC
Zero-Code Tempco
LSB
±0.5 ±2.0
INLIntegral Nonlinearity
±0.5 ±4.0
±1
±2
Zero-Code Offset Error
UNITSMIN TYP MAXSYMBOLPARAMETER
ZSE LSB
MAX54_A
MAX54_B
TA= T
MIN
to T
MAX
±20
Bipolar Zero Offset Error
CL= 10pF (Note 5) 25 V/µsSRVoltage-Output Slew Rate
DYNAMIC PERFORMANCE—ANALOG SECTION (RL= ∞, unipolar mode)
to ±1/2LSB of FS, CL= 10pF
1 µsOutput Settling Time
Guaranteed monotonic LSB±0.5 ±1.0DNLDifferential Nonlinearity
MAX54_C
STATIC PERFORMANCE—ANALOG SECTION (RL= ∞)
REFERENCE INPUT
MAX542
MAX542
%
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD= +5V ±5%, V
REF
= +2.5V, AGND = DGND = 0, TA= T
MIN
to T
MAX
, unless otherwise noted.)
TIMING CHARACTERISTICS
(VDD= +5V ±5%, V
REF
= +2.5V, AGND = DGND = 0, CMOS inputs, TA= T
MIN
to T
MAX
, unless otherwise noted.)
Note 1: Gain Error tested at V
REF
= 2.0V, 2.5V, and 3.0V.
Note 2: R
OUT
tolerance is typically ±20%.
Note 3: Min/max range guaranteed by gain-error test. Operation outside min/max limits will result in degraded performance.
Note 4: Reference input resistance is code dependent, minimum at 8555 hex.
Note 5: Slew-rate value is measured from 0% to 63%.
Note 6: Guaranteed by design. Not production tested.
Code = 0000 hex; CS = V
DD
;
LDAC = 0;
SCLK, DIN = 0 to V
DD
levels
Major-carry transition
VIN= 0
Code = 0000 hex, V
REF
= 1Vp-p at 100kHz
Code = 0000 hex
Code = FFFF hex
(Note 6)
CONDITIONS
mW1.5PDPower Dissipation
mA0.3 1.1I
DD
Positive Supply Current
V4.75 5.25V
DD
Positive Supply Range
V0.40V
H
Hysteresis Voltage
pF10C
IN
Input Capacitance
mVp-p1
nVs10
nVs10DAC Glitch Impulse
Digital Feedthrough
µA±1I
IN
Input Current
V0.8V
IL
Input Low Voltage
V2.4V
IH
Input High Voltage
Reference Feedthrough
dB92SNRSignal-to-Noise Ratio
75
pF
120
C
IN
Reference Input Capacitance
UNITSMIN TYP MAXSYMBOLPARAMETER
MAX542 (Note 6)
MAX542
(Note 6)
CONDITIONS
µs20
VDDHigh to CS Low
(power-up delay)
ns45t
CL
SCLK Pulse Width Low
ns45t
CH
MHz10f
CLK
SCLK Frequency
SCLK Pulse Width High
ns50t
LDACS
CS High to LDAC Low Setup
ns50t
LDAC
LDAC Pulse Width
ns0t
DH
DIN to SCLK High Hold
ns40t
DS
DIN to SCLK High Setup
ns45t
CSS0
CS Low to SCLK High Setup
ns45t
CSS1
CS High to SCLK High Setup
ns30t
CSH0
SCLK High to CS Low Hold
ns45t
CSH1
SCLK High to CS High Hold
UNITSMIN TYP MAXSYMBOLPARAMETER
Code = FFFF hex MHz1BWReference -3dB Bandwidth
DYNAMIC PERFORMANCE—REFERENCE SECTION
STATIC PERFORMANCE—DIGITAL INPUTS
POWER SUPPLY
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
4 _______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
(VDD= 5V, V
REF
= +2.5V, TA = +25°C, unless otherwise noted.)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
-40 -20 0 20 40 60 80 100
MAX542-01
SUPPLY CURRENT (mA)
SUPPLY CURRENT
vs. TEMPERATURE
TEMPERATURE (°C)
0.35
0.34
0.33
0.32
0.31
0.30
0.29
0.28
0123456
MAX542-02
SUPPLY CURRENT (mA)
SUPPLY CURRENT
vs. REFERENCE VOLTAGE
REFERENCE VOLTAGE (V)
1.0
0.6
0.2
0
-0.2
-0.6
0.8
0.4
-0.4
-0.8
-1.0
-60
-20 20 60 100 140
MAX542-03
ZERO-CODE OFFSET ERROR (LSB)
ZERO-CODE OFFSET ERROR
vs. TEMPERATURE
TEMPERATURE (°C)
1.0
0.6
0.2
0
-0.2
-0.6
0.8
0.4
-0.4
-0.8
-1.0
-60
-20 20 60 100 140
MAX542-04
INL (LSB)
INTEGRAL NONLINEARITY
vs. TEMPERATURE
TEMPERATURE (°C)
+INL
-INL
1.00
0.50
0.25
0.75
0
-0.25
-0.50
-0.75
-1.00
0
10k 20k 30k 40k 50k 60k 70k
MAX542-07
INL (LSB)
INTEGRAL NONLINEARITY
vs. CODE
DAC CODE
1.0
0.6
0.2
0
-0.2
-0.6
0.8
0.4
-0.4
-0.8
-1.0
-60
-20 20 60 100 140
MAX542-05
DNL (LSB)
DIFFERENTIAL NONLINEARITY
vs. TEMPERATURE
TEMPERATURE (°C)
+DNL
-DNL
1.0
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
-60
-20 20 60 100 140
MAX542-06
GAIN ERROR (LSB)
GAIN ERROR
vs. TEMPERATURE
TEMPERATURE (°C)
0.25
0.75
0.50
1.00
0
-0.25
-0.50
-0.75
-1.00
0
10k 20k 30k 40k 50k 60k 70k
MAX542-08
DNL (LSB)
DIFFERENTIAL NONLINEARITY
vs. CODE
DAC CODE
200
160
120
80
40
0
0
10k 20k 30k 40k 50k 60k 70k
MAX542-09
REFERENCE CURRENT (µA)
REFERENCE CURRENT
vs. CODE
DAC CODE
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
_______________________________________________________________________________________ 5
MAX542-10
FULL-SCALE STEP RESPONSE
(f
SCLK
= 10MHz)
2µs/div
OUT
500mV/div
CL = 10pF
R
L
= ∞
1µs/div
MAX542-10A
FULL-SCALE STEP RESPONSE
(f
SCLK
= 20MHz)
2µs/div
OUT
500mV/div
400ns/div
CL = 10pF
R
L
= ∞
MAX542-11
MAJOR-CARRY OUTPUT GLITCH
2µs/div
CS
(5V/div)
OUT
(AC-COUPLED,
100mV/div)
MAX542-12
DIGITAL FEEDTHROUGH
2µs/div
SCLK
5V/div
OUT
(AC-COUPLED,
50mV/div)
CODE = 0000 hex
Typical Operating Characteristics (continued)
(VDD= +5V, V
REF
= +2.5V, TA = +25°C, unless otherwise noted.)
Pin Descriptions
+5V Supply VoltageV
DD
8
Digital GroundDGND7
Serial Data InputDIN6
Serial Clock Input. Duty cycle must be between 40% and 60%.SCLK5
Chip-Select Input
CS
4
Voltage Reference Input. Connect to external +2.5V reference.REF3
Analog GroundAGND2
DAC Output VoltageOUT1
FUNCTIONNAMEPIN
MAX541
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
6 _______________________________________________________________________________________
________________________________________________Pin Descriptions (continued)
t
CSHO
t
CH
t
CSSO
t
CL
t
DH
t
DS
t
CSH1
t
CSS1
t
LDACS
t
LDAC
CS
SCLK
DIN
LDAC*
*MAX542 ONLY
D15 D14
D0
Figure 1. Timing Diagram
+5V Supply Voltage
V
DD
Digital GroundDGND12
LDAC Input. A falling edge updates the internal DAC latch.LDAC
11
Serial Data InputDIN10
No Connection. Not internally connected.N.C.9
Serial Clock Input. Duty cycle must be between 40% and 60%.SCLK8
Chip-Select Input
CS
7
Voltage Reference Input (force). Connect REFF to external +2.5V reference.REFF6
Voltage Reference Input (sense). Connect REFS to external +2.5V reference.REFS5
Analog Ground (sense)AGNDS4
Analog Ground (force)AGNDF3
DAC Output VoltageOUT2
Feedback Resistor. Connect to external op amp’s output in bipolar mode.RFB1
FUNCTIONNAMEPIN
Junction of internal scaling resistors. Connect to external op amp’s inverting input in
bipolar mode.
INV13
14
MAX542
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
_______________________________________________________________________________________ 7
Detailed Description
The MAX541/MAX542 voltage-output, 16-bit digital-toanalog converters (DACs) offer full 16-bit performance
with less than 1LSB integral linearity error and less than
1LSB differential linearity error, thus ensuring monotonic performance. Serial data transfer minimizes the number of package pins required.
The MAX541/MAX542 are composed of two matched
DAC sections, with a 12-bit inverted R-2R DAC forming
the 12 LSBs and the 4 MSBs derived from 15 identically
matched resistors. This architecture allows the lowest
glitch energy to be transferred to the DAC output on
major-carry transitions. It also lowers the DAC output
impedance by a factor of eight compared to a standard
R-2R ladder, allowing unbuffered operation in mediumload applications.
The MAX542 provides matched bipolar offset resistors,
which connect to an external op amp for bipolar output
swings (Figure 2b). For optimum performance, the
MAX542 also provides a set of Kelvin connections to
the voltage-reference and analog-ground inputs.
MAX542
MAX400
AGNDFDGND
(GND)
V
DD
REFF
REFS
R
INV
R
FB
RFB
INV
OUT
LDAC
SCLK
DIN
CS
AGNDS
0.1µF
+5V
EXTERNAL OP AMP
MC68XXXX
PCS0
MOSI
SCLK
IC1
BIPOLAR
OUT
+5V
-5V
0.1µF
+2.5V
10µF
Figure 2b. Typical Operating Circuit—Bipolar Output
MAX541/MAX542
MAX495
DGND
( ) ARE FOR MAX542 ONLY
(GND)
V
DD
(REFS)REF (REFF)
OUT
SCLK
DIN
CS
AGND_
0.1µF
0.1µF
+5V
+2.5V
EXTERNAL OP AMP
MC68XXXX
PCS0
MOSI
SCLK
UNIPOLAR
OUT
(LDAC)
10µF
Figure 2a. Typical Operating Circuit—Unipolar Output
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
8 _______________________________________________________________________________________
Digital Interface
The MAX541/MAX542’s digital interface is a standard
3-wire connection compatible with SPI/QSPI/
MICROWIRE interfaces. The chip-select input (CS)
frames the serial data loading at the data-input pin
(DIN). Immediately following CS’s high-to-low transition,
the data is shifted synchronously and latched into the
input register on the rising edge of the serial clock input
(SCLK). After 16 data bits have been loaded into the
serial input register, it transfers its contents to the DAC
latch on CS’s low-to-high transition (Figure 3a). Note
that if CS is not kept low during the entire 16 SCLK
cycles, data will be corrupted. In this case, reload the
DAC latch with a new 16-bit word.
Alternatively, for the MAX542, LDAC allows the DAC
latch to update asynchronously by pulling LDAC low
after CS goes high (Figure 3b). Hold LDAC high during
the data-loading sequence.
External Reference
The MAX541/MAX542 operate with external voltage references from 2V to 3V. The reference voltage determines the DAC’s full-scale output voltage. Kelvin
connections are provided with the MAX542 for optimum
performance.
Power-On Reset
The MAX541/MAX542 have a power-on reset circuit to
set the DAC’s output to 0V in unipolar mode when V
DD
is first applied. This ensures that unwanted DAC output
voltages will not occur immediately following a system
power-up, such as after a loss of power. In bipolar
mode, the DAC output is set to -V
REF
.
CS
SCLK
DIN
MSB
LSB
D15 D8 D7 D6 D5 D4 D3 D2 D1 D0
DAC
UPDATED
D14 D13 D12 D11 D10 D9
CS
SCLK
DIN
LDAC
MSB
LSB
D15
D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1
D0
DAC
UPDATED
Figure 3a. MAX541/MAX542 3-Wire Interface Timing Diagram (
LDAC
= DGND for MAX542)
Figure 3b. MAX542 4-Wire Interface Timing Diagram
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
_______________________________________________________________________________________ 9
Applications Information
Reference and Analog Ground Inputs
The MAX541/MAX542 operate with external voltage references from 2V to 3V, and maintain 16-bit performance
if certain guidelines are followed when selecting and
applying the reference. Ideally, the reference’s
temperature coefficient should be less than
0.4ppm/°C to maintain 16-bit accuracy to within 1LSB
over the 0°C to +70°C commercial temperature range.
Since this converter is designed as an inverted R-2R
voltage-mode DAC, the input resistance seen by the voltage reference is code-dependent. The worst-case inputresistance variation is from 11.5kΩ (at code 8555 hex) to
200kΩ (at code 0000 hex). The maximum change in load
current for a 2.5V reference is 2.5V / 11.5k Ω = 217µA;
therefore, the required load regulation is 7ppm/mA for a
maximum error of 0.1LSB. This implies a reference
output impedance of less than 18mΩ. In addition, the
impedance of the signal path from the voltage
reference to the reference input must be kept low
because it contributes directly to the load-regulation
error.
The requirement for a low-impedance voltage reference
is met with capacitor bypassing at the reference inputs
and ground. A 0.1µF ceramic capacitor with short leads
between REFF and AGNDF (MAX542), or REF and
AGND (MAX541), provides high-frequency bypassing.
A surface-mount ceramic chip capacitor is preferred
because it has the lowest inductance. An additional
10µF between REFF and AGNDF (MAX542), or REF
and AGND (MAX541), provides low-frequency bypassing. A low-ESR tantalum, film, or organic semiconductor
capacitor works well. Leaded capacitors are acceptable because impedance is not as critical at lower frequencies. The circuit can benefit from even larger
bypassing capacitors, depending on the stability of the
external reference with capacitive loading. If separate
force and sense lines are not used, tie the appropriate
force and sense pins together close to the package.
AGND must also be low impedance, as load-regulation
errors will be introduced by excessive AGND resistance. As in all high-resolution, high-accuracy applications, separate analog and digital ground planes yield
the best results. Tie DGND to AGND at the AGND pin to
form the “star” ground for the DAC system. Always refer
remote DAC loads to this system ground for the best
possible performance.
Unbuffered Operation
Unbuffered operation reduces power consumption as
well as offset error contributed by the external output
buffer. The R-2R DAC output is available directly at
OUT, allowing 16-bit performance from +V
REF
to AGND
without degradation at zero scale. The DAC’s output
impedance is also low enough to drive medium loads
(RL> 60kΩ) without degradation of INL or DNL; only
the gain error is increased by externally loading the
DAC output.
External Output Buffer Amplifier
The requirements on the external output buffer amplifier
change whether the DAC is used in the unipolar or
bipolar mode of operation. In unipolar mode, the output
amplifier is used in a voltage-follower connection. In
bipolar mode (MAX542 only), the amplifier operates
with the internal scaling resistors (Figure 2b). In each
mode, the DAC’s output resistance is constant and is
independent of input code; however, the output amplifier’s input impedance should still be as high as possible
to minimize gain errors. The DAC’s output capacitance
is also independent of input code, thus simplifying stability requirements on the external amplifier.
In bipolar mode, a precision amplifier operating with
dual power supplies (such as the MAX400) provides
the ±V
REF
output range. In single-supply applications,
precision amplifiers with input common-mode ranges
including AGND are available; however, their output
swings do not normally include the negative rail
(AGND) without significant degradation of performance.
A single-supply op amp, such as the MAX495, is suitable if the application does not use codes near zero.
Since the LSBs for a 16-bit DAC are extremely small
(38.15µV for V
REF
= 2.5V), pay close attention to the
external amplifier’s input specification. The input offset
voltage can degrade the zero-scale error and might
require an output offset trim to maintain full accuracy if
the offset voltage is greater than 1/2LSB. Similarly, the
input bias current multiplied by the DAC output resistance (typically 6.25kΩ) contributes to the zero-scale
error. Temperature effects also must be taken into consideration. Over the 0°C to +70°C commercial temperature range, the offset voltage temperature coefficient
(referenced to +25°C) must be less than 0.42µV/°C to
add less than 1/2LSB of zero-scale error. The external
amplifier’s input resistance forms a resistive divider with
the DAC output resistance, which results in a gain error.
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
10 ______________________________________________________________________________________
To contribute less than 1/2LSB of gain error, the input
resistance typically must be greater than:
The settling time is affected by the buffer input capacitance, the DAC’s output capacitance, and PC board
capacitance. The typical DAC output voltage settling
time is 1µs for a full-scale step. Settling time can be
significantly less for smaller step changes. Assuming a
single time-constant exponential settling response, a
full-scale step takes 12 time constants to settle to within
1/2LSB of the final output voltage. The time constant is
equal to the DAC output resistance multiplied by the
total output capacitance. The DAC output capacitance
is typically 10pF. Any additional output capacitance will
increase the settling time.
The external buffer amplifier’s gain-bandwidth product
is important because it increases the settling time by
adding another time constant to the output response.
The effective time constant of two cascaded systems,
each with a single time-constant response, is approximately the root square sum of the two time constants.
The DAC output’s time constant is 1µs / 12 = 83ns,
ignoring the effect of additional capacitance. If the time
constant of an external amplifier with 1MHz bandwidth
is 1 / 2π (1MHz) = 159ns, then the effective time constant of the combined system is:
This suggests that the settling time to within 1/2LSB of
the final output voltage, including the external buffer
amplifier, will be approximately 12 · 180ns = 2.15µs.
Digital Inputs and Interface Logic
The digital interface for the 16-bit DAC is based on a
3-wire standard that is compatible with SPI, QSPI, and
MICROWIRE interfaces. The three digital inputs (CS,
DIN, and SCLK) load the digital input data serially into
the DAC. LDAC (MAX542) updates the DAC output
asynchronously.
All of the digital inputs include Schmitt-trigger buffers to
accept slow-transition interfaces. This means that optocouplers can interface directly to the MAX541/MAX542
without additional external logic. The digital inputs are
compatible with TTL/CMOS-logic levels.
Unipolar Configuration
Figure 2a shows the MAX541/MAX542 configured for
unipolar operation with an external op amp. The op amp
is set for unity gain, and Table 1 lists the codes for this
circuit.
Bipolar Configuration
Figure 2b shows the MAX542 configured for bipolar
operation with an external op amp. The op amp is set
for unity gain with an offset of -1/2V
REF
. Table 2 lists the
offset binary codes for this circuit.
Power-Supply Bypassing and
Ground Management
For optimum system performance, use PC boards with
separate analog and digital ground planes. Wire-wrap
boards are not recommended. Connect the two ground
planes together at the low-impedance power-supply
source. Connect DGND and AGND together at the IC.
The best ground connection can be achieved by connecting the DAC’s DGND and AGND pins together and
connecting that point to the system analog ground
plane. If the DAC’s DGND is connected to the system
digital ground, digital noise may get through to the
DAC’s analog portion.
Bypass V
DD
with a 0.1µF ceramic capacitor connected
between VDDand AGND. Mount it with short leads
close to the device. Ferrite beads can also be used to
further isolate the analog and digital power supplies.
83ns 159ns 180ns
22
()
+
()
=
6.25k
121
2
819M
16
ΩΩ÷
=
Table 1. Unipolar Code Table
Table 2. Bipolar Code Table
0V0000 0000 0000 0000
V
REF
· (1 / 65,536)
0000 0000 0000 0001
V
REF
· (32,768 / 65,536) =
1/
2
V
REF
1000 0000 0000 0000
V
REF
· (65,535 / 65,536)
1111 1111 1111 1111
ANALOG OUTPUT, V
OUT
MSB LSB
DAC LATCH CONTENTS
-V
REF
· (32,768 / 32,768) = -V
REF
0000 0000 0000 0000
-V
REF
· (1 / 32,768)
0111 1111 1111 1111
0V1000 0000 0000 0000
+V
REF
· (1 / 32,768)
1000 0000 0000 0001
+V
REF
· (32,767 / 32,768)
1111 1111 1111 1111
ANALOG OUTPUT, V
OUT
MSB LSB
DAC LATCH CONTENTS
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
______________________________________________________________________________________ 11
TRANSISTOR COUNT: 2209
SUBSTRATE CONNECTED TO DGND
_____________________Chip Information
PART TEMP. RANGE PIN-PACKAGE
MAX541AEPA -40°C to +85°C 8 Plastic DIP
MAX541CEPA -40°C to +85°C 8 Plastic DIP
MAX541BESA -40°C to +85°C
8 SO
MAX541CESA -40°C to +85°C 8 SO
INL
(LSB)
±1
±4
±2
±4
MAX541AESA -40°C to +85°C 8 SO ±1
MAX542ACPD
0°C to +70°C 14 Plastic DIP
MAX542BCPD 0°C to +70°C 14 Plastic DIP
±1
±2
Ordering Information (continued)
*Dice are tested at TA= +25°C, DC parameters only.
**Contact factory for availability.
MAX542CCPD 0°C to +70°C 14 Plastic DIP
MAX542ACSD 0°C to +70°C 14 SO
MAX542CCSD 0°C to +70°C 14 SO
MAX542BC/D 0°C to +70°C Dice*
±4
±1
±4
±2
MAX542BCSD 0°C to +70°C 14 SO ±2
MAX542AEPD -40°C to +85°C 14 Plastic DIP
MAX542BEPD -40°C to +85°C 14 Plastic DIP
±1
±2
MAX542AESD -40°C to +85°C 14 SO
MAX542BESD -40°C to +85°C 14 SO
±1
±2
MAX542CEPD -40°C to +85°C 14 Plastic DIP ±4
MAX542CESD -40°C to +85°C 14 SO
MAX542CMJD -55°C to +125°C 14 Ceramic SB**±4±4
MAX541BEPA -40°C to +85°C 8 Plastic DIP ±2
16-BIT DAC
16-BIT DATA LATCH
SERIAL INPUT REGISTER
CONTROL
LOGIC
MAX541
REF
CS
DIN
SCLK
AGND
OUT
V
DD
DGND
Functional Diagrams (continued)
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
MAX541/MAX542
+5V, Serial-Input, Voltage-Output, 16-Bit DACs
PDIPN.EPS
________________________________________________________Package Information
SOICN.EPS
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