Page 1
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For small orders, phone 1-800-835-8769.
General Description
The MAX5188 is a dual 8-bit, alternate-phase-update,
current-output digital-to-analog converter (DAC)
designed for superior performance in systems requiring
analog signal reconstruction with low distortion and
low-power operation. The MAX5191 provides equal
specifications, with on-chip output resistors for voltageoutput operation. Both devices are designed for 10pVs
glitch operation to reduce distortion and minimize
unwanted spurious signal components at the output. An
on-board +1.2V bandgap circuit provides a well-regulated, low-noise reference that may be disabled for
external reference operation.
The MAX5188/MAX5191 are designed to provide a high
level of signal integrity for the least amount of power
dissipation. Both DACs operate from a +2.7V to +3.3V
single supply. Additionally, these DACs have three
modes of operation: normal, low-power standby, and
full shutdown. A full shutdown provides the lowest possible power dissipation with a maximum shutdown current of 1µA. A fast wake-up time (0.5µs) from standby
mode to full DAC operation allows for power conservation by activating the DACs only when required.
The MAX5188/MAX5191 are available in a 28-pin QSOP
package and are specified for the extended (-40°C to
+85°C) temperature range. For pin-compatible 10-bit
versions, refer to the MAX5182/MAX5185 data sheet.
Applications
Signal Reconstruction Applications
Digital Signal Processing
Arbitrary Waveform Generators
Imaging Applications
Features
♦ +2.7V to +3.3V Single-Supply Operation
♦ Wide Spurious-Free Dynamic Range: 70dB
at f
OUT
= 2.2MHz
♦ Fully Differential Outputs for Each DAC
♦ ±0.5% FSR Gain Mismatch Between DAC Outputs
♦ Low-Current Standby or Full Shutdown Modes
♦ Internal +1.2V Low-Noise Bandgap Reference
♦ Small 28-Pin QSOP Package
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
________________________________________________________________ Maxim Integrated Products 1
19-1580; Rev 0; 12/99
Pin Configuration
Ordering Information
PART
MAX5188BEEI
MAX5191BEEI
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
28 QSOP
28 QSOP
TOP VIEW
CREF1
OUT1P
OUT1N
AGND
AV
DACEN
CLK
N.C.
REN
DGND
DGND
1
2
3
4
5
DD
PD
CS
D0
MAX5188
6
MAX5191
7
8
9
10
11
12
13
14
QSOP
28
CREF2
27
OUT2P
26
OUT2N
25
REFO
24
REFR
23
DGND
22
DV
DD
21
D7
20
D6
19
D5
18
D4
17
D3
16
D2
15
D1
Page 2
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
2 ________________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(AVDD= DVDD= +3V ±10%, AGND = DGND = 0, f
CLK
= 40MHz, IFS= 1mA, 400Ω differential output, CL= 5pF, TA= T
MIN
to T
MAX
,
unless otherwise noted. Typical values are at T
A
= +25°C.)
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.
AVDD, DVDDto AGND, DGND .................................-0.3V to +6V
Digital Inputs to DGND.............................................-0.3V to +6V
OUT1P, OUT1N, OUT2P, OUT2N, CREF1,
CREF2 to AGND ....................................................-0.3V to +6V
V
REF
to AGND ..........................................................-0.3V to +6V
AV
DD
to DVDD.....................................................................±3.3V
AGND to DGND.....................................................-0.3V to +0.3V
Maximum Current into Any Pin............................................50mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin QSOP (derate 9.00mW/°C above +70°C)..........725mW
Operating Temperature Ranges
MAX5188/MAX5191BEEI..................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
f
OUT
= 550kHz
f
OUT
= 2.2MHz
f
OUT
= 550kHz
f
OUT
= 2.2MHz
f
OUT
= 550kHz
Ω
DAC External Output Resistor
Load
400MAX5188 only
mAFull-Scale Output Current I
FS
0.5 1 1.5MAX5188 only
µAOutput Leakage Current -1 1DACEN = 0, MAX5188 only
UNITS
Bits
LSB
LSB
LSB
LSB
ns
pVs
dBc
dB
dB
dB
nVs
pA/√Hz
LSB
mV
V
PARAMETER SYMBOL MIN TYP MAX
Full-Scale Error -20 ±4 +20
-1 +1
Differential Nonlinearity DNL -1 ±0.25 +1
Output Settling Time 25
Glitch Impulse 10
72
Spurious-Free Dynamic Range
to Nyquist
SFDR
57 70
Resolution N 8
Integral Nonlinearity INL
-1 ±0.25 +1
-70
Total Harmonic Distortion
to Nyquist
THD
-68 -63
52
Signal-to-Noise Ratio
to Nyquist
SNR
46 52
DAC-to-DAC Output Isolation -60
Clock and Data Feedthrough 50
Output Noise 10
Gain Mismatch Between DAC
Outputs
±0.5 ±1
Full-Scale Output Voltage V
FS
400
Voltage Compliance of Output -0.3 0.8
CONDITIONS
f
CLK
= 40MHz
(Note 1)
MAX5188
Guaranteed monotonic
To ±0.5LSB error band
f
CLK
= 40MHz
f
OUT
= 2.2MHz
All 0s to all 1s
f
OUT
= 2.2MHz
f
CLK
= 40MHz
f
OUT
= 2.2MHz
LSB
Zero-Scale Error
-4 +4MAX5191
STATIC PERFORMANCE
ANALOG OUTPUT
DYNAMIC PERFORMANCE
Page 3
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(AVDD= DVDD= +3V ±10%, AGND = DGND = 0, f
CLK
= 40MHz, IFS= 1mA, 400Ω differential output, CL= 5pF, TA= T
MIN
to T
MAX
,
unless otherwise noted. Typical values are at T
A
= +25°C.)
CS Fall to CLK Fall Time
5 ns
DACEN Rise Time to V
OUT
0.5 µs
PD Fall Time to V
OUT
50 µs
Clock Period t
CLK
25 ns
Clock High Time t
CH
10 ns
Clock Low Time t
CL
10 ns
PARAMETER SYMBOL MIN TYP MAX UNITS
Current Gain (IFS/ I
REF
) 8 mA/mA
Reference Supply Rejection 0.5 mV/V
Reference Output Drive
Capability
I
REFOUT
10 µA
Analog Power-Supply Voltage AV
DD
2.7 3.3 V
Analog Supply Current I
AVDD
2.7 5 mA
Digital Power-Supply Voltage DV
DD
2.7 3.3 V
Digital Supply Current I
DVDD
4.2 5 mA
Output Voltage Range V
REF
1.12 1.2 1.28 V
Output Voltage Temperature
Drift
TCV
REF
50 ppm/°C
Standby Current I
STANDBY
1 1.5 mA
Shutdown Current I
SHDN
0.5 1 µA
Digital Input High Voltage V
IH
2 V
Digital Input Low Voltage V
IL
0.8 V
Digital Input Current I
IN
±1 µA
Digital Input Capacitance C
IN
10 pF
DAC1 DATA to CLK Rise Setup
Time
t
DS1
10 ns
DAC2 DATA to CLK Fall Setup
Time
t
DS2
10 ns
DAC1 CLK Rise to DATA Hold
Time
t
DH1
0 ns
DAC2 CLK Fall to DATA Hold
Time
t
DH2
0 ns
CS Fall to CLK Rise Time
5 ns
CONDITIONS
PD = 0, DACEN = 0, digital inputs at 0 or DV
DD
PD = 1, DACEN = X, digital inputs at 0 or DV
DD
(X = don’t care)
PD = 0, DACEN = 1, digital inputs at 0 or DV
DD
PD = 0, DACEN = 1, digital inputs at 0 or DV
DD
VIN= 0 or DV
DD
REFERENCE
POWER REQUIREMENTS
LOGIC INPUTS AND OUTPUTS
TIMING CHARACTERISTICS
Note 1: Excludes reference and reference resistor (MAX5191) tolerance.
Page 4
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
4 _______________________________________________________________________________________
Typical Operating Characteristics
(AVDD= DVDD= +3V, AGND = DGND = 0, 400Ω differential output, IFS= 1mA, CL= 5pF, TA = +25°C, unless otherwise noted.)
0.150
0.125
0.100
0.075
0.050
0.025
0
-0.025
-0.050
0 32 64 96 128 160 192 224 256
INTEGRAL NONLINEARITY
vs. INPUT CODE
MAX5188/91-01
INPUT CODE
INL (LSB)
0.100
0.075
0.050
0.025
0
-0.025
-0.050
-0.075
0 32 64 96 128 160 192 224 256
DIFFERENTIAL NONLINEARITY
vs. INPUT CODE
MAX5188/91-02
INPUT CODE
DNL (LSB)
3.00
2.75
2.50
2.25
2.00
2.5 4.03.0 3.5 4.5 5.0 5.5
ANALOG SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5188/91-03
SUPPLY VOLTAGE (V)
ANALOG SUPPLY CURRENT (mA)
MAX5188
MAX5191
3.00
2.75
2.25
2.50
2.00
-40 35-15 10 60 85
ANALOG SUPPLY CURRENT
vs. TEMPERATURE
MAX5188/91-04
TEMPERATURE (°C)
ANALOG SUPPLY CURRENT (mA)
MAX5188
MAX5191
10
8
6
4
2
0
2.5 4.03.0 3.5 4.5 5.0 5.5
DIGITAL SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5188/91-05
SUPPLY VOLTAGE (V)
DIGITAL SUPPLY CURRENT (mA)
MAX5188
MAX5191
4.00
3.75
3.25
3.50
3.00
-40 35-15 10 60 85
DIGITAL SUPPLY CURRENT
vs. TEMPERATURE
MAX5188/91-06
TEMPERATURE (°C)
DIGITAL SUPPLY CURRENT (mA)
MAX5188
MAX5191
620
610
600
580
590
570
560
2.5 4.03.0 3.5 4.5 5.0 5.5
STANDBY CURRENT
vs. SUPPLY VOLTAGE
MAX5188/91-07
SUPPLY VOLTAGE (V)
STANDBY CURRENT (µA)
MAX5188
MAX5191
600
590
570
560
580
550
-40 35-15 10 60 85
STANDBY CURRENT
vs. TEMPERATURE
MAX5188/91-08
TEMPERATURE (°C)
STANDBY CURRENT (µA)
MAX5188
MAX5191
3.8
3.7
3.6
3.5
3.4
2.5 4.03.0 3.5 4.5 5.0 5.5
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
MAX5188/91-09
SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT (µA)
MAX5188
MAX5191
Page 5
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(AVDD= DVDD= +3V, AGND = DGND = 0, 400Ω differential output, IFS= 1mA, CL= 5pF, TA = +25°C, unless otherwise noted.)
INTERNAL REFERENCE VOLTAGE
vs. SUPPLY VOLTAGE
1.28
1.27
1.26
MAX5188
1.25
REFERENCE VOLTAGE (V)
1.24
1.23
2.5 4.03.0 3.5 4.5 5.0 5.5
MAX5191
SUPPLY VOLTAGE (V)
OUT_P
150mV/div
INTERNAL REFERENCE VOLTAGE
1.28
1.27
MAX5188/91-11
1.26
1.25
REFERENCE VOLTAGE (V)
1.24
1.23
-40 35-15 10 60 85
DYNAMIC RESPONSE RISE TIME
vs. TEMPERATURE
MAX5188
MAX5191
TEMPERATURE (°C)
MAX5188/91-14
OUT_P
150mV/div
4
MAX5188/91-12
3
2
OUTPUT CURRENT (mA)
1
0
0 300100 200 400 500
DYNAMIC RESPONSE FALL TIME
OUTPUT CURRENT
vs. REFERENCE CURRENT
REFERENCE CURRENT (µA)
MAX5188/91-15
MAX5188/91-13
OUT_N
100mV/div
OUT_P
100mV/div
OUT_N
150mV/div
SETTLING TIME
12.5ns/div
50ns/div
MAX5188/91-16
0
-10
-20
-30
-40
-50
-60
(dBc)
-70
-80
-90
-100
-110
-120
0246
OUTPUT FREQUENCY (MHz)
OUT_N
150mV/div
FFT PLOT, DAC1
f
CLK
f
OUT
81012141618
= 40MHz
= 2.2MHz
MAX5188/91-17
20
50ns/div
(dBc)
-100
-110
-120
-10
-20
-30
-40
-50
-60
-70
-80
-90
0
0246
FFT PLOT, DAC2
f
CLK
f
OUT
81012141618
OUTPUT FREQUENCY (MHz)
= 40MHz
= 2.2MHz
MAX5188/91-18
20
Page 6
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(AVDD= DVDD= +3V, AGND = DGND = 0, 400Ω differential output, IFS= 1mA, CL= 5pF, TA = +25°C, unless otherwise noted.)
SPURIOUS-FREE DYNAMIC RANGE
vs. CLOCK FREQUENCY
100
90
80
70
SFDR (dBc)
60
50
40
10 302515 20 35 40 45 50 55 60
CLOCK FREQUENCY (MHz)
DAC2
DAC1
MAX5188/91-19
SPURIOUS-FREE DYNAMIC RANGE vs. OUTPUT
FREQUENCY AND CLOCK FREQUENCY, DAC1
78
f
= 40MHz
76
74
72
SFDR (dBc)
70
68
66
500 1100 1300700 900 1500 1700 1900 2100 2300
OUTPUT FREQUENCY (kHz)
f
CLK
= 60MHz
f
CLK
f
= 30MHz
CLK
CLK
= 50MHz
f
f
CLK
CLK
= 20MHz
= 10MHz
MAX5188/91-20
SPURIOUS-FREE DYNAMIC RANGE vs. OUTPUT
FREQUENCY AND CLOCK FREQUENCY, DAC2
78
f
= 50MHz f
CLK
76
74
72
SFDR (dBc)
70
68
66
f
CLK
500 1100 1300700 900 1500 1700 1900 2100 2300
= 20MHz
CLK
= 10MHz
f
= 60MHz
CLK
f
CLK
OUTPUT FREQUENCY (kHz)
= 30MHz
CLK
= 40MHzf
MULTITONE SPURIOUS-FREE DYNAMIC
RANGE vs. OUTPUT FREQUENCY
0
-10
-20
-30
-40
-50
SFDR (dBc)
-60
-70
-80
-120
0862 4 10 12 14 16 18 20
OUTPUT FREQUENCY (MHz)
MAX5188/91-21
MAX5188/91-24
SIGNAL-TO-NOISE PLUS DISTORTION
vs. OUTPUT FREQUENCY
62.5
62.0
61.5
SINAD (dB)
61.0
60.5
60.0
0 1500500 1000 2000 2500
OUPUT FREQUENCY (kHz)
DAC1
SPURIOUS-FREE DYNAMIC RANGE
vs. FULL-SCALE OUTPUT CURRENT
74
72
70
68
SFDR (dBc)
66
64
62
60
0.50 0.75 1.00 1.25 1.50
FULL-SCALE OUTPUT CURRENT (mA)
MAX5188/91-23
DAC2
MAX5188/91-26
Page 7
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
_______________________________________________________________________________________ 7
Pin Description
Data Bit D7 (MSB)D721
Reference Bias Bypass, DAC2CREF228
Positive Analog Output, DAC2. Current output for the MAX5188; voltage output for the MAX5191.OUT2P27
Negative Analog Output, DAC2. Current output for the MAX5188; voltage output for the MAX5191.OUT2N26
Reference OutputREFO25
PIN FUNCTIONNAME
Data Bit D0 (LSB)D014
Data Bits D1–D6D1–D615–20
Digital Supply, +2.7V to +3.3VDV
DD
22
Reference InputREFR24
Clock InputCLK9
Not Connected. Do not connect to this pin.
N.C.10
Active-Low Reference Enable. Connect to DGND to activate on-chip +1.2V reference.
REN
11
Digital GroundDGND12, 13, 23
Active-Low Chip Select
CS
8
Power-Down Select
0: Enter DAC standby mode (DACEN = DGND) or power-up DAC (DACEN = DVDD)
1: Enter shutdown mode
PD7
DAC Enable, Digital Input
0: Enter DAC standby mode with PD = DGND
1: Power-up DAC with PD = DGND
X: Enter shutdown mode with PD = DV
DD
(X = don’t care)
DACEN6
Negative Analog Output, DAC1. Current output for the MAX5188; voltage output for the MAX5191.OUT1N3
Analog GroundAGND4
Analog Positive Supply, +2.7V to +3.3VAV
DD
5
Positive Analog Output, DAC1. Current output for the MAX5188; voltage output for the MAX5191.OUT1P2
1 Reference Bias Bypass, DAC1CREF1
Page 8
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
8 _______________________________________________________________________________________
Detailed Description
The MAX5188/MAX5191 are dual 8-bit digital-to-analog
converters (DACs) capable of operating with clock
speeds up to 40MHz. Each of these dual converters
consists of separate input and DAC registers, followed
by a current-source array capable of generating up to
1.5mA full-scale output current (Figure 1). An integrated +1.2V voltage reference and control amplifier determine the data converters’ full-scale output currents/
voltages. Careful reference design ensures close gain
matching and excellent drift characteristics. The
MAX5191’s voltage output operation features matched
400Ω on-chip resistors that convert the current from the
current array into a voltage.
Internal Reference
and Control Amplifier
The MAX5188/MAX5191 provide an integrated
50ppm/°C, +1.2V, low-noise bandgap reference that
can be disabled and overridden by an external reference voltage. REFO serves either as an input for an
external reference or as an output for the integrated reference. If REN is connected to DGND, the internal ref-
erence is selected and REFO provides a +1.2V output.
Due to its limited 10µA output drive capability, the
REFO pin must be buffered with an external amplifier if
heavier loading is required.
The MAX5188/MAX5191 also employ a control amplifier, designed to simultaneously regulate the full-scale
output current I
FS
for both MAX5188/MAX5191 outputs.
The output current is calculated as follows:
IFS= 8 · I
REF
where I
REF
is the reference output current (I
REF
=
V
REFO
/ R
SET
) and IFSis the full-scale output current.
R
SET
is the reference resistor that determines the
amplifier’s output current (Figure 2) on the MAX5188.
This current is mirrored into the current-source array,
where it is equally distributed between matched current
segments and summed to valid output current readings
for the DACs.
Inside the MAX5191, each output current (DAC1 and
DAC2) is converted to an output voltage (V
OUT1
,
V
OUT2
) with two internal, ground-referenced, 400Ω load
resistors. Using the internal +1.2V reference voltage,
the integrated reference output current resistor of the
MAX5191 (R
SET
= 9.6kΩ) sets I
REF
to 125µA and I
FS
to
1mA.
Figure 1. Functional Diagram
REN
1.2V REF
REFO
REFR
9.6k*
CLK
*INTERNAL 400Ω AND 9.6kΩ RESISTORS FOR MAX5191 ONLY.
AV
DAC 1 SWITCHES
DAC 2 SWITCHES
OUTPUT
LATCHES
MSB DECODE
INPUT
LATCHES
AGND CS DACEN PD
DD
CURRENT-
SOURCE ARRAY
OUTPUT
LATCHES
MSB DECODE
INPUT
LATCHES
D7–D0
CREF1
CREF2
OUT1P
OUT1N
OUT2P
OUT2N
400Ω*
MAX5188
MAX5191
DV
DD
400Ω*
400Ω*
DGND
400Ω*
Page 9
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
_______________________________________________________________________________________ 9
External Reference
To disable the MAX5188/MAX5191’s internal reference,
connect REN to DVDD. A temperature-stable external
reference may now be applied to drive the REFO pin
(Figure 3) to set the full-scale output. Choose a reference that can supply at least 150µA to drive the bias
circuit that generates the cascode current for the current array. For improved accuracy and drift performance, choose a fixed output voltage reference such
as the +1.2V, 25ppm/°C MAX6520 bandgap reference.
Standby Mode
To enter the lower-power standby mode, connect digital inputs PD and DACEN to DGND. In standby, both
the reference and the control amplifier are active with
the current array inactive. To exit this condition, DACEN
must be pulled high with PD held at DGND. The
MAX5188/MAX5191 typically require 50µs to wake up
and allow both the outputs and the reference to settle.
Shutdown Mode
For lowest power consumption, the MAX5188/MAX5191
provide a power-down mode in which the reference,
control amplifier, and current array are inactive and the
DAC’s supply current is reduced to 1µA. To enter this
mode, connect PD to DVDD. To return to active mode,
connect PD to DGND and DACEN to DVDD. About 50µs
are required for the devices to leave shutdown mode
and settle their outputs to the values prior to shutdown.
Table 1 lists the power-down mode selection.
Figure 2. Setting IFSwith the Internal +1.2V Reference and Control Amplifier
Table 1. Power-Down Mode Selection
X = Don’t care
MAX5191
MAX5188
MAX5191
MAX5188
1 X Shutdown
AGND
0 0 Standby
AGND
PD
(POWER-DOWN SELECT)
DACEN
(DAC ENABLE)
POWER-DOWN
MODE
OUTPUT STATE
High-Z
0 1 Wake-Up Last state prior to standby mode
High-Z
OPTIONAL EXTERNAL BUFFER
FOR HEAVIER LOADS
MAX4040
REFO
C
*
AGND
V
REF
I
=
REF
R
SET
*COMPENSATION CAPACITOR (C
COMP
COMP
R
SET
AGND
= 100nF) **9.6kΩ REFERENCE CURRENT SET RESISTOR
REFR
I
REF
R
SET
9.6k
REN
+1.2V
BANDGAP
REFERENCE
**
INTERNAL TO MAX5191 ONLY. USE EXTERNAL
FOR MAX5188.
R
SET
DGND
MAX5188
MAX5191
CURRENT-
SOURCE ARRAY
I
FS
Page 10
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
10 ______________________________________________________________________________________
Figure 4. Timing Diagram
Figure 3. MAX5188/MAX5191 Using an External Reference
DV
DD
0.1µF10µF
AV
DD
EXTERNAL
+1.2V
REFERENCE
MAX6520
AGND
R
AGND
REFO
REFR
SET
t
CLK
CLK
REN
+1.2V
BANDGAP
REFERENCE
I
REF
9.6k*
DGND
CURRENT-
SOURCE ARRAY
I
FS
MAX5188
MAX5191
*9.6kΩ REFERENCE CURRENT SET RESISTOR
INTERNAL TO MAX5191 ONLY. USE EXTERNAL
FOR MAX5188.
R
SET
t
CL
t
CH
N - 1
D0–D7
OUT1 N - 1
OUT2
DAC1 DAC2 DAC1 DAC2 DAC1 DAC2
N - 1
t
DS2
t
DS1
N - 1
N
t
DH1
N
N
t
DH2
N
N + 1 N + 1
N + 1
N + 1
Page 11
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
______________________________________________________________________________________ 11
Timing Information
Both internal DAC cells write to their outputs in alternate
phase (Figure 4). The input latch of the first DAC
(DAC1) is loaded after the clock signal transitions high.
When the clock signal transitions low, the input latch of
the second DAC (DAC2) is loaded. The contents of the
first input latch are shifted into the DAC1 register on the
rising edge of the clock; the contents of the second
input latch are shifted into the input register of DAC2 on
the falling edge of the clock. Both outputs are updated
on alternate phases of the clock.
Outputs
The MAX5188 outputs are designed to supply 1mA fullscale output currents into 400Ω loads in parallel with a
capacitive load of 5pF. The MAX5191 features integrat-
ed 400Ω resistors that restore the array currents into
proportional, differential voltages of 400mV. These differential output voltages can then be used to drive a
balun transformer or a low-distortion, high-speed operational amplifier to convert the differential voltage into a
single-ended voltage.
Applications Information
Static and Dynamic
Performance Definitions
Integral Nonlinearity
Integral nonlinearity (INL) (Figure 5a) is the deviation of
the values on an actual transfer function from either a
best-straight-line fit (closest approximation to the actual
transfer curve) or a line drawn between the endpoints
Figure 5a. Integral Nonlinearity
Figure 5b. Differential Nonlinearity
Figure 5c. Offset Error
Figure 5d. Gain Error
7
6
5
4
3
ANALOG OUTPUT VALUE
2
1
0
000 010001 011 100 101 110
AT STEP
001 (1/4 LSB )
DIGITAL INPUT CODE
AT STEP
011 (1/2 LSB )
111
6
5
4
3
2
ANALOG OUTPUT VALUE
1
0
000 010001 011 100 101
1 LSB
DIFFERENTIAL
LINEARITY ERROR (+1/4 LSB)
DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY
ERROR (-1/4 LSB)
1 LSB
3
2
1
ANALOG OUTPUT VALUE
0
000 010001 011
ACTUAL
DIAGRAM
ACTUAL
OFFSET
POINT
IDEAL OFFSET
POINT
DIGITAL INPUT CODE
IDEAL DIAGRAM
OFFSET ERROR
(+1 1/4 LSB)
7
6
5
ANALOG OUTPUT VALUE
4
0
000 101100 110 111
IDEAL FULL-SCALE OUTPUT
GAIN ERROR
(-1 1/4 LSB)
IDEAL DIAGRAM
DIGITAL INPUT CODE
ACTUAL
FULL-SCALE
OUTPUT
Page 12
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
12 ______________________________________________________________________________________
of the transfer function once offset and gain errors have
been nullified. For a DAC, the deviations are measured
at every single step.
Differential Nonlinearity
Differential nonlinearity (DNL) (Figure 5b) is the difference between an actual step height and the ideal value
of 1LSB. A DNL error specification of less than 1LSB
guarantees no missing codes and a monotonic transfer
function.
Offset Error
Offset error (Figure 5c) is the difference between the
ideal and the actual offset point. For a DAC, the offset
point is the step value when the digital input is zero.
This error affects all codes by the same amount and
can usually be compensated by trimming.
Gain Error
Gain error (Figure 5d) is the difference between the
ideal and the actual full-scale output voltage on the
transfer curve, after nullifying the offset error. This error
alters the slope of the transfer function and corresponds to the same percentage error in each step.
Settling Time
The settling time is the amount of time required from the
start of a transition until the DAC output settles its new
output value to within the converter’s specified accuracy.
Digital Feedthrough
Digital feedthrough is the noise generated on a DAC’s
output when any digital input transitions. Proper board
layout and grounding will significantly reduce this
noise, but there will always be some feedthrough
caused by the DAC itself.
Total Harmonic Distortion
Total harmonic distortion (THD) is the ratio of the RMS
sum of the input signal’s first five harmonics to the fundamental itself. This is expressed as:
where V
1
is the fundamental amplitude, and V2through
V5are the amplitudes of the 2nd- through 5th-order
harmonics.
Spurious-Free Dynamic Range
Spurious-free dynamic range (SFDR) is the ratio of RMS
amplitude of the fundamental (maximum signal component) to the RMS value of the next-largest distortion
component.
Differential to Single-Ended Conversion
The MAX4108 low-distortion, high input-bandwidth
amplifier may be used to generate a voltage from the
MAX5188’s current-array output. The differential voltage across OUT1P (or OUT2P) and OUT1N (or OUT2N)
is converted into a single-ended voltage by designing
an appropriate operational amplifier configuration as
shown in Figure 6.
Grounding and Power-Supply Decoupling
Grounding and power-supply decoupling strongly influence the performance of the MAX5188/MAX5191.
Unwanted digital crosstalk may couple through the
input, reference, power-supply, and ground connections, which may affect dynamic specifications like SNR
or SFDR. In addition, electromagnetic interference
(EMI) can either couple into or be generated by the
MAX5188/MAX5191. Therefore, grounding and powersupply decoupling guidelines for high-speed, high-frequency applications should be closely followed.
First, a multilayer PC board with separate ground and
power-supply planes is recommended. High-speed
signals should run on controlled impedance lines
directly above the ground plane. Since the MAX5188/
MAX5191 have separate analog and digital ground
buses (AGND and DGND, respectively), the PC board
should also have separate analog and digital ground
sections with only one point connecting the two. Digital
signals should run above the digital ground plane, and
analog signals should run above the analog ground
plane.
Both devices have two power-supply inputs: analog
V
DD
(AVDD) and digital VDD(DVDD). Each AVDDinput
should be decoupled with parallel 10µF and 0.1µF
ceramic-chip capacitors as close to the pin as possible. Their opposite ends should have the shortest possible connection to the ground plane. The DVDDpins
should also have separate 10µF and 0.1µF capacitors,
again adjacent to their respective pins. Try to minimize
the analog load capacitance for proper operation. For
best performance, bypass CREF1 and CREF2 with lowESR, 0.1µF capacitors to AVDD.
The power-supply voltages should also be decoupled
with large tantalum or electrolytic capacitors at the
point they enter the PC board. Ferrite beads with additional decoupling capacitors forming a pi network could
also improve performance.
THD
=
2222
VVVV
+++
()
2345
⋅20
log
V
1
Page 13
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
______________________________________________________________________________________ 13
Chip Information
TRANSISTOR COUNT: 9464
SUBSTRATE CONNECTED TO GND
Figure 6. Differential to Single-Ended Conversion Using the MAX4108 Low-Distortion Amplifier
+3V
+3V
10µF
R
SET
D0–D7
**
0.1µF
0.1µF
CLK
REFO
REFR
AV
DD
MAX5188
MAX5191
10µF
AVDDAV
DD
0.1µF
0.1µF
DV
CREF1
DD
CREF2
OUT1P
OUT1N
OUT2P
OUT2N
REN AGNDDGND
400Ω*
400Ω*
400Ω*
400Ω*
0.1µF
402Ω
402Ω
402Ω
402Ω
402Ω
402Ω
402Ω
402Ω
+5V
-5V
+5V
-5V
OUTPUT1
MAX4108
OUTPUT2
MAX4108
**MAX5188 ONLY
*400Ω RESISTORS INTERNAL TO MAX5191 ONLY.
Page 14
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
14 ______________________________________________________________________________________
Package Information
QSOP.EPS
Page 15
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
______________________________________________________________________________________ 15
NOTES
Page 16
MAX5188/MAX5191
Dual, 8-Bit, 40MHz, Current/Voltage,
Alternate-Phase Output DACs
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.
16 ____________________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.
NOTES
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