19-1317; Rev 1; 12/97
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
________________________Applications
Industrial Process Control
Motion Control
Digital Offset and Gain
Adjustment
Digitally Programmable
4–20mA Current Loops
Remote Industrial Controls
Automatic Test Equipment
____________________________Features
♦ 12-Bit Dual DAC with Configurable Output
Amplifier
♦ Single-Supply Operation: +5V (MAX5156)
+3V (MAX5157)
♦ Rail-to-Rail Output Swing
♦ Low Quiescent Current: 500µA (normal operation)
2µA (shutdown mode)
♦ Power-On Reset Clears DAC Outputs to Zero
♦ SPI/QSPI and Microwire Compatible
♦ Space-Saving 16-Pin QSOP Package
_______________Ordering Information
PART
MAX5156ACPE
MAX5156BCPE
MAX5156ACEE
MAX5156BCEE
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
16 Plastic DIP
16 Plastic DIP
16 QSOP
16 QSOP
INL
(LSB)
±1/2
±1
±1/2
±1
Ordering Information continued at end of data sheet.
Pin Configuration appears at end of data sheet.
_________________________________________________________Functional Diagram
DOUT
CL
PDL
DECODE
CONTROL
DGND
INPUT
REG A
AGND
VDD
DAC
REG A
16-BIT
SHIFT
REGISTER
REFA
DAC A
MAX5156
MAX5157
LOGIC
OUTPUT
INPUT
REG B
DAC
REG B
DAC B
DIN
FBA
OUTB
FBB
SR
CONTROL
CS
OUTA
SCLK UPO
REFB
Rail-to-Rail is a registered trademark of Nippon Motorola Ltd. SPI and QSPI are trademarks of Motorola, Inc.
Microwire is a trademark of National Semiconductor Corp.
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
MAX5156/MAX5157
_______________General Description
The MAX5156/MAX5157 low-power, serial, voltage-output, dual 12-bit digital-to-analog converters (DACs)
consume only 500µA from a single +5V (MAX5156) or
+3V (MAX5157) supply. These devices feature Rail-toRail® output swing and are available in space-saving
16-pin QSOP and DIP packages. Access to the inverting input allows for specific gain configurations, remote
sensing, and high output current capability, making
these devices ideally suited for industrial process controls. These devices are also well suited for digitally
programmable (4–20mA) current loops.
The 3-wire serial interface is SPI™/QSPI™ and
Microwire™ compatible. Each DAC has a doublebuffered input organized as an input register followed
by a DAC register, which allows the input and DAC registers to be updated independently or simultaneously.
Additional features include a programmable shutdown
(2µA), hardware-shutdown lockout, a separate voltage
reference for each DAC, power-on reset, and an activelow clear input (CL) that resets all registers and DACs to
zero. The MAX5156/MAX5157 provide a programmable
logic output pin for added functionality, and a serialdata output pin for daisy chaining.
MAX5156/MAX5157
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
ABSOLUTE MAXIMUM RATINGS
VDD to AGND............................................................-0.3V to +6V
VDD to DGND ...........................................................-0.3V to +6V
AGND to DGND ..................................................................±0.3V
FBA, FBB to AGND.....................................-0.3V to (VDD + 0.3V)
REF_, OUT_ to AGND.................................-0.3V to (VDD + 0.3V)
Digital Inputs (SCLK, DIN, CS, CL, PDL)
to DGND ................................................................-0.3V to +6V
Digital Outputs (DOUT, UPO) to DGND .....-0.3V to (VDD + 0.3V)
Maximum Current into Any Pin .........................................±20mA
Continuous Power Dissipation (TA = +70°C)
Plastic DIP (derate 10.5mW/°C above +70°C) .............593mW
QSOP (derate 8.30mW/°C above +70°C) .....................667mW
CERDIP (derate 10.00mW/°C above +70°C) ................800mW
Operating Temperature Ranges
MAX5152_C_E/MAX5153_C_E ...........................0°C to +70°C
MAX5152_E_E/MAX5153_E_E..........................-40°C to +85°C
MAX5152_MJE/MAX5153_MJE ......................-55°C to +125°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°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.
ELECTRICAL CHARACTERISTICS—MAX5156
(VDD = +5V ±10%, VREFA = VREFB = 2.5V, RL = 10kΩ, CL = 100pF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at
TA = +25°C, output buffer connected in unity-gain configuration (Figure 9).)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
STATIC PERFORMANCE
Resolution
N
12
Integral Nonlinearity
INL
(Note 1)
Differential Nonlinearity
DNL
Guaranteed monotonic
VOS
Code = 10
Offset Error
Offset Tempco
TCVOS
PSRR
LSB
±1
LSB
3
-0.5
Gain-Error Tempco
±1/2
±1
±6
Normalized to 2.5V
Gain Error
VDD Power-Supply Rejection Ratio
Bits
MAX5156A
MAX5156B
Normalized to 2.5V
3
4.5V ≤ VDD ≤ 5.5V
20
mV
ppm/°C
±3
LSB
ppm/°C
200
µV/V
REFERENCE INPUT
Reference Input Range
REF
Reference Input Resistance
RREF
0
Minimum with code 1554 hex
14
VDD - 1.4
V
20
kΩ
MULTIPLYING-MODE PERFORMANCE
Reference 3dB Bandwidth
Input code = 1FFE hex,
VREF = 0.67Vp-p at 2.5VDC
600
kHz
Reference Feedthrough
Input code = 0000 hex,
VREF = (VDD - 1.4Vp-p) at 1kHz
-85
dB
Input code = 1FFE hex,
VREF = 1Vp-p at 2.5VDC, f = 25kHz
82
dB
Signal-to-Noise plus
Distortion Ratio
SINAD
DIGITAL INPUTS
Input High Voltage
VIH
CL, PDL, CS, DIN, SCLK
Input Low Voltage
VIL
CL, PDL, CS, DIN, SCLK
Input Hysteresis
VHYS
Input Leakage Current
IIN
Input Capacitance
CIN
2
3
V
0.8
200
VIN = 0V to VDD
0.001
8
_______________________________________________________________________________________
V
mV
±1
µA
pF
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
(VDD = +5V ±10%, VREFA = VREFB = 2.5V, RL = 10kΩ, CL = 100pF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at
TA = +25°C, output buffer connected in unity-gain configuration (Figure 9).)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DIGITAL OUTPUTS (DOUT, UPO)
Output High Voltage
VOH
ISOURCE = 2mA
Output Low Voltage
VOL
ISINK = 2mA
VDD - 0.5
V
0.13
0.40
V
DYNAMIC PERFORMANCE
Voltage Output Slew Rate
SR
Output Settling Time
To 1/2LSB of full-scale, VSTEP = 2.5V
Output Voltage Swing
Current into FBA or FBB
Rail-to-rail (Note 2)
V/µs
15
µs
0 to VDD
IFB
0
Time Required to Exit Shutdown
CS = VDD, fDIN = 100kHz, VSCLK = 5Vp-p
Digital Feedthrough
0.75
Digital Crosstalk
V
±0.1
µA
25
µs
5
nV-s
5
nV-s
POWER SUPPLIES
Positive Supply Voltage
VDD
Power-Supply Current
IDD
Power-Supply Current in
Shutdown
4.5
(Note 3)
IDD(SHDN) (Note 3)
Reference Current in Shutdown
5.5
V
0.5
0.65
mA
2
10
µA
0
±1
µA
TIMING CHARACTERISTICS
SCLK Clock Period
tCP
100
ns
SCLK Pulse Width High
tCH
40
ns
SCLK Pulse Width Low
tCL
40
ns
CS Fall to SCLK Rise Setup Time
tCSS
40
ns
SCLK Rise to CS Rise Hold Time
tCHS
0
ns
DIN Setup Time
tDS
40
ns
DIN Hold Time
tDH
0
ns
SCLK Rise to DOUT Valid
Propagation Delay
tDO1
CLOAD = 200pF
80
ns
SCLK Fall to DOUT Valid
Propagation Delay
tDO2
CLOAD = 200pF
80
ns
SCLK Rise to CS Fall Delay
tCS0
10
ns
CS Rise to SCLK Rise Hold
tCS1
40
ns
CS Pulse Width High
tCSW
100
ns
Note 1:
Note 2:
Note 3:
Note 4:
(Note 4)
Accuracy is specified from code 10 to code 4095.
Accuracy is better than 1LSB for VOUT greater than 6mV and less than VDD - 50mV. Guaranteed by PSRR test at the end points.
Digital inputs are set to either VDD or DGND, code = 0000 hex, RL = ∞.
SCLK minimum clock period includes rise and fall times.
_______________________________________________________________________________________
3
MAX5156/MAX5157
ELECTRICAL CHARACTERISTICS—MAX5156 (continued)
MAX5156/MAX5157
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
ELECTRICAL CHARACTERISTICS—MAX5157
(VDD = +2.7V to +3.6V, VREFA = VREFB = 1.25V, RL = 10kΩ, CL = 100pF, TA = TMIN to TMAX, unless otherwise noted. Typical values
are at TA = +25°C, output buffer connected in unity-gain configuration (Figure 9).)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
STATIC PERFORMANCE
Resolution
N
12
Integral Nonlinearity
INL
(Note 5)
Differential Nonlinearity
DNL
Guaranteed monotonic
VOS
Code = 20
Offset Error
Offset Tempco
TCVOS
MAX5157A
±1
MAX5157B
±2
±1
±6
Normalized to 1.25V
6
Gain Error
PSRR
Normalized to 1.25V
6
2.7V ≤ VDD ≤ 3.6V
20
LSB
LSB
mV
ppm/°C
-0.5
Gain-Error Tempco
VDD Power-Supply Rejection Ratio
Bits
±4
LSB
ppm/°C
320
µV/V
REFERENCE INPUT (VREF)
Reference Input Range
REF
Reference Input Resistance
RREF
0
Minimum with code 1554 hex
14
VDD - 1.4
V
20
kΩ
MULTIPLYING-MODE PERFORMANCE
Reference 3dB Bandwidth
Input code = 1FFE hex,
VREF(AC) = 0.67Vp-p at 1.25VDC
600
kHz
Reference Feedthrough
Input code = 0000 hex,
VREF = (VDD - 1.4V) at 1kHz
-92
dB
Input code = 1FFE hex,
VREF = 1Vp-p at 1.25VDC, f = 15kHz
73
dB
Signal-to-Noise plus Distortion
Ratio
SINAD
DIGITAL INPUTS
Input High Voltage
Input Low Voltage
Input Hysteresis
VIH
CL, PDL, CS, DIN, SCLK
VIL
CL, PDL, CS, DIN, SCLK
2.2
0.8
VHYS
Input Leakage Current
IIN
Input Capacitance
CIN
V
200
VIN = 0V to VDD
0
V
mV
±0.1
8
µA
pF
DIGITAL OUTPUTS (DOUT, UPO)
Output High Voltage
VOH
ISOURCE = 2mA
Output Low Voltage
VOL
ISINK = 2mA
VDD - 0.5
V
0.13
0.4
V
DYNAMIC PERFORMANCE
Voltage Output Slew Rate
SR
Output Settling Time
To 1/2LSB of full-scale, VSTEP = 1.25V
Output Voltage Swing
Rail-to-rail (Note 6)
Current into FBA or FBB
IFB
Digital Crosstalk
4
V/µs
18
µs
0 to VDD
0
Time Required to Exit Shutdown
Digital Feedthrough
0.75
CS = VDD, fDIN = 100kHz, VSCLK = 3Vp-p
V
±0.1
µA
25
µs
5
nV-s
5
nV-s
_______________________________________________________________________________________
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
(VDD = +2.7V to +3.6V, VREFA = VREFB = 1.25V, RL = 10kΩ, CL = 100pF, TA = TMIN to TMAX, unless otherwise noted. Typical values
are at TA = +25°C, output buffer connected in unity-gain configuration (Figure 9).)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER SUPPLIES
Positive Supply Voltage
VDD
Power-Supply Current
IDD
Power-Supply Current in
Shutdown
2.7
(Note 7)
IDD(SHDN) (Note 7)
Reference Current in
Shutdown
3.6
V
0.5
0.6
mA
1
8
µA
±1
µA
TIMING CHARACTERISTICS
SCLK Clock Period
tCP
100
ns
SCLK Pulse Width High
tCH
(Note 4)
40
ns
SCLK Pulse Width Low
tCL
40
ns
CS Fall to SCLK Rise Setup
Time
tCSS
40
ns
SCLK Rise to CS Rise Hold
Time
tCHS
0
ns
DIN Setup Time
tDS
50
ns
DIN Hold Time
tDH
0
ns
SCLK Rise to DOUT Valid
Propagation Delay
tDO1
CLOAD = 200pF
120
ns
SCLK Fall to DOUT Valid
Propagation Delay
tDO2
CLOAD = 200pF
120
ns
SCLK Rise to CS Fall Delay
tCS0
10
ns
CS Rise to SCLK Rise Hold
tCS1
40
ns
CS Pulse Width High
tCSW
100
ns
Note 5: Accuracy is specified from code 20 to code 4095.
Note 6: Accuracy is better than 1LSB for VOUT greater than 6mV and less than VDD - 100mV. Guaranteed by PSRR test at the end
points.
Note 7: Digital inputs are set to either VDD or DGND, code = 0000 hex, RL = ∞.
_______________________________________________________________________________________
5
MAX5156/MAX5157
ELECTRICAL CHARACTERISTICS—MAX5157 (continued)
__________________________________________Typical Operating Characteristics
(VDD = +5V, RL = 10kΩ, CL = 100pF, FB_ connected to OUT_, TA = +25°C, unless otherwise noted.)
MAX5156
SUPPLY CURRENT
vs. TEMPERATURE
-8
-10
-12
-14
CODE = 1FFE (HEX)
VREF = 1Vp-p @ 2.5VDC
CODE = 1FFE (HEX)
-40
0.55
0.50
CODE = 0000 (HEX)
-50
-60
-70
0.45
-16
VREF = 0.67Vp-p @ 2.5VDC
CODE = 1FFE (HEX)
-18
-80
0.40
-20
0
600
1200
1800
2400
-90
-60
3000
-20
20
60
100
140
0
10
100
TEMPERATURE (°C)
FREQUENCY (kHz)
FULL-SCALE ERROR vs. RESISTIVE LOAD
REFERENCE FEEDTHROUGH AT 1kHz
POWER-DOWN CURRENT
vs. TEMPERATURE
-0.2
-0.3
-0.4
-80
-90
-100
-110
-120
-130
3.0
MAX5156 TOC06
VREF = 3.6Vp-p @ 1.88VDC
CODE = 0000 (HEX)
-70
RELATIVE OUTPUT (dB)
-0.1
-60
POWER-DOWN CURRENT (µA)
-50
MAX5156 TOC04
VREF = 2.5V
MAX5156-TOC05
FREQUENCY (kHz)
0
FULL-SCALE ERROR (LSB)
-30
THD + NOISE (dB)
-6
∞
MAX5156 TOC03
RL =
SUPPLY CURRENT (mA)
-4
RELATIVE OUTPUT (dB)
0.60
MAX5156 TOC01
0
-2
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX5156 TOC02
REFERENCE VOLTAGE INPUT
FREQUENCY RESPONSE
2.5
2.0
1.5
1.0
0.5
-140
-0.5
1
10
100
1000
-30
5
25
45
OUTPUT FFT PLOT
DYNAMIC-RESPONSE RISE TIME
MAX5156 TOC09
CS
5V/div
AC COUPLED
CS
5V/div
AC COUPLED
-40
OUT_
500mV/div
-50
OUT_
500mV/div
-60
-70
-80
-90
-100
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
2µs/div
2µs/div
FREQUENCY (kHz)
6
85 105 125
DYNAMIC-RESPONSE FALL TIME
MAX5156 TOC08
VREF = 3.6Vp-p @ 1.8VDC
f = 1kHz
CODE = 1FFE (HEX)
NOTE: RELATIVE TO FULL SCALE
65
TEMPERATURE (°C)
FREQUENCY (kHz)
MAX5156-TOC07
-20
-55 -35 -15
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
RL (kΩ)
0
-10
0
-150
0.1
RELATIVE OUTPUT (dB)
MAX5156/MAX5157
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
_______________________________________________________________________________________
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
MAX5157
SUPPLY CURRENT
vs. TEMPERATURE
-8
-10
-12
-14
500
1000
1500
2000
2500
-60
-70
CODE = 0000 (HEX)
-90
-60
-20
20
60
100
140
0
10
100
FREQUENCY (kHz)
FULL-SCALE ERROR vs. RESISTIVE LOAD
REFERENCE FEEDTHROUGH AT 1kHz
POWER-DOWN CURRENT
vs. TEMPERATURE
-70
RELATIVE OUTPUT (dB)
-0.2
-0.3
-0.4
VREF = 1.6Vp-p @ 0.88VDC
CODE = 0000 (HEX)
-80
-90
-100
-110
-120
-130
-0.5
3.0
2.0
1.5
1.0
0.5
0
-150
-0.6
1
2.5
-140
VREF = 1.25V
0.1
MAX5156 TOC15
-60
POWER-DOWN CURRENT (µA)
MAX5156 TOC13
-50
MAX5156-TOC14
TEMPERATURE (°C)
-0.1
FULL-SCALE ERROR (LSB)
-50
FREQUENCY (kHz)
0
10
100
1000
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
RL (kΩ)
FREQUENCY (kHz)
OUTPUT FFT PLOT
DYNAMIC-RESPONSE RISE TIME
-55 -35 -15
5
25
45
MAX5156-TOC16
VREF = 1.6Vp-p @ 0.88VDC
f = 1kHz
CODE = 1FFE (HEX)
NOTE: RELATIVE TO FULL SCALE
65
85 105 125
TEMPERATURE (°C)
DYNAMIC-RESPONSE FALL TIME
MAX5156 TOC17
0
RELATIVE OUTPUT (dB)
0.50
0.40
0
-30
CODE = 1FFE (HEX)
-80
-20
-20
-40
VREF = 0.67Vp-p @ 1.25VDC
CODE = 1FFE (HEX)
-18
VREF = 1Vp-p @ 1VDC
CODE = 1FFE (HEX)
0.55
0.45
-16
-10
∞
THD + NOISE (dB)
-6
-30
MAX5156 TOC11
RL =
SUPPLY CURRENT (mA)
-4
RELATIVE OUTPUT (dB)
0.60
MAX5156 TOC10
0
-2
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX5156 TOC12
REFERENCE VOLTAGE INPUT
FREQUENCY RESPONSE
MAX5156/MAX5157
____________________________Typical Operating Characteristics (continued)
(VDD = +3V, RL = 10kΩ, CL = 100pF, FB_ connected to OUT_, TA = +25°C, unless otherwise noted.)
MAX5156 TOC18
CS
2V/div
CS
2V/div
-40
-50
OUT_
500mV/div
-60
OUT_
500mV/div
-70
-80
-90
-100
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
2µs/div
2µs/div
FREQUENCY (kHz)
_______________________________________________________________________________________
7
____________________________Typical Operating Characteristics (continued)
(VDD = +5V (MAX5156), VDD = +3V (MAX5157), RL = 10kΩ, CL = 100pF, FB_ connected to OUT_, TA = TMIN to TMAX, unless
otherwise noted.)
MAX5156/MAX5157
MAX5157
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5156
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
CODE = 1FFE (HEX)
0.50
SUPPLY CURRENT (mA)
CODE = 1FFE (HEX)
MAX5156 TOC19a
0.55
0.55
MAX5156 TOC19
0.60
SUPPLY CURRENT (mA)
MAX5156/MAX5157
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
0.50
CODE = 0000 (HEX)
0.45
0.40
0.45
CODE = 0000 (HEX)
0.40
0.35
0.35
0.30
0.30
4.50
4.75
5.00
5.25
2.7
5.50
SUPPLY VOLTAGE (V)
3.0
3.3
3.6
SUPPLY VOLTAGE (V)
MAX5156
MAJOR-CARRY TRANSITION
MAX5156 TOC20
CS
2V/div
OUT_
10mV/div
AC COUPLED
2µs/div
TRANSITION FROM 1000 (HEX) TO 0FFE (HEX)
MAX5156
ANALOG CROSSTALK
MAX5156
DIGITAL FEEDTHROUGH
MAX5156 TOC22
MAX5156 TOC21
SCLK
5V/div
OUTA
1V/div
OUTA
500µV/div
AC COUPLED
OUTB
200µV/div
AC COUPLED
1µs/div
200µs/div
8
_______________________________________________________________________________________
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
PIN
NAME
1
AGND
Analog Ground
2
OUTA
DAC A Output Voltage
3
FBA
4
REFA
FUNCTION
DAC A Output Amplifier Feedback Input. Inverting input of the output amplifier.
Reference for DAC A
5
CL
Active-Low Clear Input. Resets all registers to zero. DAC outputs go to 0V.
6
CS
Chip-Select Input
7
DIN
Serial Data Input
8
SCLK
Serial Clock Input
9
DGND
Digital Ground
10
DOUT
Serial Data Output
11
UPO
User-Programmable Output
12
PDL
Power-Down Lockout. The device cannot be powered down when PDL is low.
13
REFB
14
FBB
15
OUTB
DAC B Output Voltage
16
VDD
Positive Power Supply
Reference Input for DAC B
DAC B Output Amplifier Feedback Input. Inverting input of the output amplifier.
_______________Detailed Description
The MAX5156/MAX5157 dual, 12-bit, voltage-output
DACs are easily configured with a 3-wire serial interface. These devices include a 16-bit data-in/data-out
shift register, and each DAC has a double-buffered
input comprised of an input register and a DAC register
(see Functional Diagram). Both DACs use an inverted
R-2R ladder network that produces a weighted voltage
proportional to the input voltage value. Each DAC has
its own reference input to facilitate independent fullscale values. Figure 1 depicts a simplified circuit diagram of one of the two DACs.
Reference Inputs
The reference inputs accept both AC and DC values
with a voltage range extending from 0V to (VDD - 1.4V).
Determine the output voltage using the following equation:
VOUT = VREF x NB / 4096
where NB is the numeric value of the DAC’s binary input
code (0 to 4095) and VREF is the reference voltage.
The reference input impedance ranges from 14kΩ (1554
hex) to several giga ohms (with an input code of 0000
hex). This reference input capacitance is code dependent and typically ranges from 15pF with an input code
of all zeros to 50pF with a full-scale input code.
FB_
R
2R
2R
D0
R
2R
D9
OUT_
R
2R
2R
D10
D11
REF_
AGND
SHOWN FOR ALL 1s ON DAC
Figure 1. Simplified DAC Circuit Diagram
Output Amplifier
The output amplifier’s inverting input is available to the
user, allowing force and sense capability for remote
sensing and specific gain configurations. The inverting
input can be connected to the output to provide a unitygain buffered output. The output amplifiers have a typical slew rate of 0.75V/µs and settle to 1/2LSB within
15µs, with a load of 10kΩ in parallel to 100pF. Loads
less than 2kΩ degrade performance.
_______________________________________________________________________________________
9
MAX5156/MAX5157
______________________________________________________________Pin Description
MAX5156/MAX5157
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
Table 1. Serial-Interface Programming Commands
16-BIT SERIAL WORD
FUNCTION
A0
C1
C0
D11................D0
MSB
LSB
S0
0
0
1
12 bits of DAC data
0
Load input register A; DAC register is unchanged.
1
0
1
12 bits of DAC data
0
Load input register B; DAC register is unchanged.
0
1
0
12 bits of DAC data
0
Load input register A; all DAC registers are updated.
1
1
0
12 bits of DAC data
0
Load input register B; all DAC registers are updated.
0
1
1
12 bits of DAC data
0
Load all DAC registers from the shift register (start up both DACs
with new data).
1
0
0
xxxxxxxxxxxx
0
Update both DAC registers from their respective input registers
(start up both DACs with data previously stored in the input
registers).
1
1
1
xxxxxxxxxxxx
0
Shut down both DACs if PDL = 1.
0
0
0
0 0 1 x xxxxxxxx
0
Update DAC register A from input register A (start up DAC A with
data previously stored in input register A).
0
0
0
1 0 1 x xxxxxxxx
0
Update DAC register B from input register B (start up DAC B with
data previously stored in input register B).
0
0
0
1 1 0 x xxxxxxxx
0
Shut down DAC A when PDL = 1.
0
0
0
1 1 1 x xxxxxxxx
0
Shut down DAC B when PDL = 1.
0
0
0
0 1 0 x xxxxxxxx
0
UPO goes low (default).
0
0
0
0 1 1 x xxxxxxxx
0
UPO goes high.
0
0
0
1 0 0 1 xxxxxxxx
0
Mode 1, DOUT clocked out on SCLK’s rising edge.
0
0
0
1 0 0 0 xxxxxxxx
0
Mode 0, DOUT clocked out on SCLK’s falling edge (default).
0
0
0
0 0 0 x xxxxxxxx
0
No operation (NOP).
“x” = don’t care
Note: D11, D10, D9, and D8 become control bits when A0, C1, and C0 = 0. S0 is a sub bit, always zero.
Power-Down Mode
The MAX5156/MAX5157 feature a software-programmable shutdown mode that reduces the typical supply
current to 2µA. The two DACs can be shut down independently or simultaneously by using the appropriate
programming word. For instance, enter shutdown mode
(for both DACs) by writing an input control word of
111XXXXXXXXXXXX0 (Table 1). In shutdown mode, the
reference inputs and amplifier outputs become high
impedance, and the serial interface remains active.
Data in the input registers is saved, allowing the
MAX5156/MAX5157 to recall the output state prior to
entering shutdown when returning to normal mode. Exit
shutdown by recalling the previous condition or by
10
updating the DAC with new information. When returning
to normal operation (exiting shutdown), wait 20µs for
output stabilization.
Serial Interface
The MAX5156/MAX5157 3-wire serial interface is compatible with both Microwire (Figure 2) and SPI/QSPI
(Figure 3) serial-interface standards. The 16-bit serial
input word consists of an address bit, two control bits,
12 bits of data (MSB to LSB), and one sub bit as shown
in Figure 4. The address and control bits determine the
response of the MAX5156/MAX5157, as outlined in
Table 1.
______________________________________________________________________________________
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
SK
DIN
SO
CS
I/O
MICROWIRE
PORT
Figure 2. Connections for Microwire
The general timing diagram in Figure 5 illustrates how
data is acquired. Driving CS low enables the device to
receive data. Otherwise, the interface control circuitry is
disabled. With CS low, data at DIN is clocked into the
register on the rising edge of SCLK. As CS goes high,
data is latched into the input and/or DAC registers
depending on the address and control bits. The maximum clock frequency guaranteed for proper operation
is 10MHz. Figure 6 depicts a more detailed timing diagram of the serial interface.
VCC
SS
DIN
MAX5156
MAX5157
MOSI
SCLK
SCK
CS
SPI/QSPI
PORT
Serial Data Output (DOUT)
DOUT is the internal shift register’s output. It allows for
daisy-chaining and data readback. The MAX5156/
MAX5157 can be programmed to shift data out of
DOUT on SCLK’s falling edge (Mode 0) or rising edge
(Mode 1). Mode 0 provides a lag of 16 clock cycles,
which maintains compatibility with SPI/QSPI and
Microwire interfaces. In Mode 1, the output data lags
15.5 clock cycles. On power-up, the device defaults to
Mode 0.
I/O
CPOL = 0, CPHA = 0
Figure 3. Connections for SPI/QSPI
MSB...................................................................................LSB
16 Bits of Serial Data
Address Bits
Control Bits
MSB...DataBits...LSB
Sub
Bit
A0
C1, C0
D11.......................D0
S0
12 Data Bits
0
1 Address/2 Control Bits
Figure 4. Serial-Data Format
User-Programmable Logic Output (UPO)
UPO allows an external device to be controlled through
the MAX5156/MAX5157 serial interface (Table 1), thereby reducing the number of microcontroller I/O pins
required. On power-up, UPO is low.
Power-Down Lockout Input (PDL)
PDL disables software shutdown when low. When in
shutdown, transitioning PDL from high to low wakes up
the part with the output set to the state prior to shutdown. PDL can also be used to asynchronously wake
up the device.
______________________________________________________________________________________
11
MAX5156/MAX5157
MAX5156
MAX5157
SCLK
The MAX5156/MAX5157’s digital inputs are double
buffered, which allows any of the following: loading the
input register(s) without updating the DAC register(s),
updating the DAC register(s) from the input register(s),
or updating the input and DAC registers concurrently.
The address and control bits allow the DACs to act
independently.
Send the 16-bit data as one 16-bit word (QSPI) or two
8-bit packets (SPI, Microwire), with CS low during this
period. The address and control bits determine which
register will be updated, and the state of the registers
when exiting shutdown. The 3-bit address/control
determines the following:
• registers to be updated
• clock edge on which data is clocked out via the serial data output (DOUT)
• state of the user-programmable logic output
• configuration of the device after shutdown
MAX5156/MAX5157
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
CS
COMMAND
EXECUTED
SCLK
1
DIN
8
C1
A0
C0 D11 D10
D9
D8
9
D7
D6
16
D5
D4
D3
D2
D1
D0
S0
Figure 5. Serial-Interface Timing Diagram
tCSW
CS
tCSS
tCSO
tCL
tCP
tCH
tCSH
tCS1
SCLK
tDS
tDH
DIN
Figure 6. Detailed Serial-Interface Timing Diagram
SCLK
SCLK
MAX5156
MAX5157
DIN
DOUT
CS
SCLK
MAX5156
MAX5157
DIN
DOUT
CS
MAX5156
MAX5157
DIN
CS
DOUT
TO OTHER
SERIAL DEVICES
Figure 7. Daisy Chaining MAX5156/MAX5157s
Daisy Chaining Devices
Any number of MAX5156/MAX5157s can be daisy
chained by connecting the DOUT pin of one device to the
DIN pin of the following device in the chain (Figure 7).
Since the MAX5156/MAX5157’s DOUT has an internal
active pull-up, the DOUT sink/source capability determines the time required to discharge/charge a capaci-
12
tive load. Refer to the digital output VOH and VOL specifications in the Electrical Characteristics.
Figure 8 shows an alternative method of connecting
several MAX5156/MAX5157s. In this configuration, the
data bus is common to all devices; data is not shifted
through a daisy-chain. More I/O lines are required in
this configuration because a dedicated chip-select
input (CS) is required for each IC.
______________________________________________________________________________________
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
MAX5156/MAX5157
DIN
SCLK
CS1
CS2
TO OTHER
SERIAL DEVICES
CS3
CS
CS
MAX5156
MAX5157
CS
MAX5156
MAX5157
MAX5156
MAX5157
SCLK
SCLK
SCLK
DIN
DIN
DIN
Figure 8. Multiple MAX5156/MAX5157s Sharing a Common DIN Line
Table 2. Unipolar Code Table (Gain = +1)
DAC CONTENTS
MSB
LSB
+5V/+3V
REF_
VDD
MAX5156
MAX5157
1111
1111
1111(0)
4095
+VREF
4096
1000
0000
0001(0)
2049
+VREF
4096
1000
0000
0000(0)
0111
1111
1111(0)
2047
+VREF
4096
0000
0000
0001(0)
1
+VREF
4096
0000
0000
0000(0)
FB_
DAC
OUT_
AGND
ANALOG OUTPUT
DGND
Figure 9. Unipolar Output Circuit
VREF
2048
+VREF
=
2
4096
0V
Note: ( ) are for the sub bit.
__________Applications Information
Unipolar Output
Figure 9 depicts the MAX5156/MAX5157 configured for
unity-gain, unipolar operation. Table 2 lists the unipolar
output codes. To increase dynamic range, specific
gain configurations can be used as shown in Figure 10.
Bipolar Output
The MAX5156/MAX5157 can be configured for a bipolar output, as shown in Figure 11. The output voltage is
given by the equation:
VOUT = VREF [((2 x NB) / 4096) - 1]
where NB represents the numeric value of the DAC’s
binary input code. Table 3 shows digital codes and the
corresponding output voltage for Figure 11’s circuit.
______________________________________________________________________________________
13
MAX5156/MAX5157
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
+5V/+3V
REF_
+5V/+3V
REF_
10k
10k
VDD
R2
MAX5156
MAX5157
VDD
FB_
V+
FB_
MAX5156
MAX5157
R1
VOUT
DAC
VOUT
OUT_
DAC _
DGND
OUT_
V-
AGND
DGND
AGND
( ) ( )( )
VOUT = 1 + R1
R2
N
VREF_
4096
Figure 10. Configurable Output Gain
Figure 11. Bipolar Output Circuit
Table 3. Bipolar Code Table
DAC CONTENTS
MSB
LSB
+5V/
+3V
ANALOG OUTPUT
2047
2048
1111
1111
1111(0)
+VREF
1000
0000
0001(0)
1
+VREF
2048
1000
0000
0000(0)
0111
1111
1111(0)
0000
0000
0000
0000
0001(0)
0000(0)
+5V/+3V
26k
AC
REFERENCE
INPUT
500mVp-p
MAX495
10k
REF_
VDD
FB_
0V
1
-VREF
2048
2047
-VREF
2048
2048
-VREF
= - VREF
2098
DAC_
OUT_
MAX5156
DGND MAX5157 AGND
Note: ( ) are for the sub bit.
Figure 12. AC Reference Input Circuit
Using an AC Reference
Harmonic Distortion and Noise
In applications where the reference has an AC signal
component, the MAX5156/MAX5157 have multiplying
capabilities within the reference input voltage range
specifications. Figure 12 shows a technique for applying a sinusoidal input REF_, where the AC signal is offset before being applied to the reference input.
The total harmonic distortion plus noise (THD+N) is typically less than -80dB at full scale with a 1Vp-p input
swing at 5kHz. The typical -3dB frequency is 600kHz
for both devices, as shown in the Typical Operating
Characteristics.
14
______________________________________________________________________________________
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
Figure 13 shows the MAX5156/MAX5157 in a digital
calibration application. With a bright value applied to
the photodiode (on), the DAC is digitally ramped up
until it trips the comparator. The microprocessor stores
this high calibration value. Repeat the process with a
dim light (off) to obtain the dark current calibration. The
microprocessor then programs the DAC to set an output voltage that is the midpoint of the two calibration
values. Applications include tachometers, motion sensing, automatic readers, and liquid clarity analysis.
V+
REF_
+5V/+3V
PHOTODIODE
VDD
MAX5156
MAX5157
V+
FB_
VOUT
OUT_
Digital Control of Gain and Offset
µP
The two DACs can be used to control the offset and
gain for curve-fitting nonlinear functions, such as transducer linearization or analog compression/expansion
applications. The input signal is used as the reference
for the gain-adjust DAC, whose output is summed with
the output from the offset-adjust DAC. The relative
weight of each DAC output is adjusted by R1, R2, R3,
and R4 (Figure 14).
DAC _
DIN
R
DGND
V-
AGND
Figure 13. Digital Calibration
+5V/+3V
VDD
FBA
VIN
DIN
SCLK
CL
R1
REFA
CONTROL/
SHIFT REGISTER
CS
DACA
OUT_A
DACB
OUT_B
R2
VOUT
R3
R4
REFB
VREF
FBB
MAX5156
MAX5157
DGND
VOUT = [GAIN] - [OFFSET]
AGND
= VIN NA
4096
[(
NB
R2
)( R1+R2
)( R4R3 )]
)(1+ R4R3 )] [(VREF 4096
NA IS THE NUMERIC VALUE OF THE INPUT CODE FOR DACA.
NB IS THE NUMERIC VALUE OF THE INPUT CODE FOR DACB.
Figure 14. Digital Control of Gain and Offset
______________________________________________________________________________________
15
MAX5156/MAX5157
Digital Calibration and
Threshold Selection
MAX5156/MAX5157
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
Digitally Programmable Current Source
Figure 15 depicts a digitally programmable, unidirectional current source that can be used in industrial control applications. The output current is:
IOUT = (VREF / R) (NB / 4096)
where NB is the DAC code and R is the sense resistor.
Power-Supply Considerations
+5V/+3V
REF_
VL
VDD
On power-up, the input and DAC registers clear (resets
to zero code). For rated performance, VREF_ should be
at least 1.4V below VDD. Bypass the power supply with
a 4.7µF capacitor in parallel with a 0.1µF capacitor to
GND. Minimize lead lengths to reduce lead inductance.
IOUT
DAC_
OUT_
MAX5156
MAX5157
2N3904
FB_
R
Grounding and Layout Considerations
Digital and AC transient signals on AGND can create
noise at the output. Connect AGND to the highest quality ground available. Use proper grounding techniques,
such as a multilayer board with a low-inductance
ground plane. Carefully lay out the traces between
channels to reduce AC cross-coupling and crosstalk.
Wire-wrapped boards and sockets are not recommended. If noise becomes an issue, shielding may be
required.
__________________Pin Configuration
TOP VIEW
AGND 1
16 VDD
OUTA 2
15 OUTB
14 FBB
FBA 3
REFA 4
CL 5
MAX5156
MAX5157
13 REFB
12 PDL
CS 6
11 UPO
DIN 7
10 DOUT
9
SCLK 8
DGND
DIP/QSOP
___________________Chip Information
DGND
AGND
Figure 15. Digitally Programmable Current Source
_Ordering Information (continued)
PART
TEMP. RANGE
PIN-PACKAGE
MAX5156AEPE
MAX5156BEPE
MAX5156AEEE
MAX5156BEEE
MAX5156BMJE
MAX5157ACPE
MAX5157BCPE
MAX5157ACEE
MAX5157BCEE
MAX5157AEPE
MAX5157BEPE
MAX5157AEEE
MAX5157BEEE
MAX5157BMJE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
16 Plastic DIP
16 Plastic DIP
16 QSOP
16 QSOP
16 CERDIP*
16 Plastic DIP
16 Plastic DIP
16 QSOP
16 QSOP
16 Plastic DIP
16 Plastic DIP
16 QSOP
16 QSOP
16 CERDIP*
INL
(LSB)
±1/2
±1
±1/2
±1
±1
±1
±2
±1
±2
±1
±2
±1
±2
±2
*Contact factory for availability.
TRANSISTOR COUNT: 3053
SUBSTRATE CONNECTED TO AGND
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
© 1997 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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