Analog Devices AD7237ATQ, AD7247ATQ, AD7247ABR, AD7247ABN, AD7247AAR Datasheet

a		LC2MOS
		Dual 12-Bit DACPORTs
		AD7237A/AD7247A

FEATURES

Complete Dual 12-Bit DAC Comprising Two 12-Bit CMOS DACs

On-Chip Voltage Reference Output Amplifiers Reference Buffer Amplifiers

Improved AD7237/AD7247: 12 V to 15 V Operation

Faster Interface –30 ns typ Data Setup Time Parallel Loading Structure: AD7247A

(8+4) Loading Structure: AD7237A Single or Dual Supply Operation

Low Power—165 mW typ in Single Supply

GENERAL DESCRIPTION

The AD7237A/AD7247A is an enhanced version of the industry standard AD7237/AD7247. Improvements include operation from 12 V to 15 V supplies, faster interface times and better reference variations with VDD. Additional features include faster settling times.

The AD7237A/AD7247A is a complete, dual, 12-bit, voltage output digital-to-analog converter with output amplifiers and Zener voltage reference on a monolithic CMOS chip. No external user trims are required to achieve full specified performance.

Both parts are microprocessor compatible, with high speed data latches and interface logic. The AD7247A accepts 12-bit parallel data which is loaded into the respective DAC latch using the WR input and a separate Chip Select input for each DAC. The AD7237A has a double buffered interface structure and an 8-bit wide data bus with data loaded to the respective input latch in two write operations. An asynchronous LDAC signal on the AD7237A updates the DAC latches and analog outputs.

A REF OUT/REF IN function is provided which allows either the on-chip 5 V reference or an external reference to be used as a reference voltage for the part. For single supply operation, two output ranges of 0 V to +5 V and 0 V to +10 V are available, while these two ranges plus an additional ±5 V range are available with dual supplies. The output amplifiers are capable of developing +10 V across a 2 kΩ load to GND.

The AD7237A/AD7247A is fabricated in Linear Compatible CMOS (LC2MOS), an advanced, mixed technology process that combines precision bipolar circuits with low power CMOS logic. Both parts are available in a 24-pin, 0.3" wide plastic and hermetic dual-in-line package (DIP) and are also packaged in a 24-lead small outline (SOIC) package.

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FUNCTIONAL BLOCK DIAGRAMS

PRODUCT HIGHLIGHTS

1.The AD7237A/AD7247A is a dual 12-bit DACPORT® on a single chip. This single chip design and small package size offer considerable space saving and increased reliability over multichip designs.

2.The improved interface times of the parts allow easy, direct interfacing to most modern microprocessors, whether they have 8-bit or 16-bit data bus structures.

3.The AD7237A/AD7247A features a wide power supply range allowing operation from 12 V supplies.

DACPORT is a registered trademark of Analog Devices, Inc.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: [phone] Fax: [phone]

AD7237A/AD7247A–SPECIFICATIONS(VDD = +12 V to +15 V,1 VSS = 0 V or –12 V to –15 V,1 AGND = DGND = 0 V [AD7237A], GND = 0 V [AD7247A], REF IN = +5 V,

RL = 2 kΩ, CL = 100 pF. All specifications TMIN to TMAX unless otherwise noted.)

Parameter	A2	B2	T2	Units	Test Conditions/Comments
STATIC PERFORMANCE
Resolution	12	12	12	Bits
Relative Accuracy3	±1	±1/2	±1/2	LSB max
Differential Nonlinearity3	±0.9	±0.9	±0.9	LSB max	Guaranteed Monotonic
Unipolar Offset Error3	±3	±3	±4	LSB max	VSS = 0 V or –12 V to –15 V4. DAC Latch Contents All 0s
Bipolar Zero Error3	±6	±4	±6	LSB max	VSS = –12 V to –15 V4. DAC Latch Contents
Full-Scale Error3, 5	±5	±5	±6	LSB max	1000 0000 0000
Full-Scale Mismatch5	±1	±1	±1	LSB typ
REFERENCE OUTPUT
REF OUT	4.97/5.03	4.97/5.03	4.95/5.05	V min/max
Reference Temperature	±25	±25	±25	ppm/°C typ
Coefficient
Reference Load Change					Reference Load Current Change (0-100 μA)
( REF OUT vs. I)	–1	–1	–1	mV max
REFERENCE INPUT					5 V ± 5%
Reference Input Range	4.75/5.25	4.75/5.25	4.75/5.25	V min/max
Input Current6	±5	±5	±5	μA max
DIGITAL INPUTS
Input High Voltage, VINH	2.4	2.4	2.4	V min
Input Low Voltage, VINL	0.8	0.8	0.8	V max
Input Current	±10	±10	±10	μA max
IIN (Data Inputs)					VIN = 0 V to VDD
Input Capacitance6	8	8	8	pF max
ANALOG OUTPUTS				kΩ min/max
Output Range Resistors	15/30	15/30	15/30
Output Voltage Ranges7	+5, +10	+5, +10	+5, +10, ±5	V	Single Supply; (VSS = 0 V)
Output Voltage Ranges7	+5, +10, ±5	+5, +10, ±5		Ω typ	Dual Supply; (VSS = –12 V to –15 V4)
DC Output Impedance	0.5	0.5	0.5
AC CHARACTERISTICS6					Settling Time to Within ±1/2 LSB of Final Value
Voltage Output Settling Time				μs max
Positive Full-Scale Change	8	8	10		DAC Latch all 0s to all 1s. Typically 5 μs
Negative Full-Scale Change	8	8	10	μs max	DAC Latch all 1s to all 0s. Typically 5 μs
Digital-to-Analog Glitch					VSS = –12 V to –15 V4.
Impulse3	30	30	30	nV secs typ	DAC Latch Contents Toggled Between all 0s and all 1s
Digital Feedthrough3	10	10	10	nV secs typ
Digital Crosstalk3	30	30	30	nV secs typ
POWER REQUIREMENTS
VDD	+10.8/+16.5	+11.4/+15.75	+11.4/+15.75	V min/max	For Specified Performance Unless Otherwise Stated
VSS	–10.8/–16.5	–11.4/–15.75	–11.4/–15.75	V min/max	For Specified Performance Unless Otherwise Stated
IDD	15	15	15	mA max	Output Unloaded. Typically 10 mA
ISS (Dual Supplies)	5	5	5	mA max	Output Unloaded. Typically 3 mA

NOTES

1Power Supply tolerance is ±10% for A version and ±5% for B and T versions.

2Temperature ranges are as follows: A, B Versions, –40°C to +85°C; T Version, –55°C to +125°C. 3See Terminology.

4With appropriate power supply tolerances.

5Measured with respect to REF IN and includes unipolar/bipolar offset error. 6Sample tested @ +25°C to ensure compliance.

70 V to +10 V range is only available with VDD ³ 14.25 V.

Specifications subject to change without notice.

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AD7237A/AD7247A

TIMING CHARACTERISTICS1, 2

(VDD = +12 V to +15 V,3 VSS = 0 V or –12 V to –15 V,3 AGND = DGND = 0 V [AD7237A],

GND = 0 V [AD7247A])

Limit at TMIN, TMAX

Limit at TMIN, TMAX

Parameter

(A, B Versions)

(T Version)

Units

Conditions/Comments

t1

0

0

ns min

to

Setup Time

CS

WR

t2

0

0

ns min

CS

to

WR

Hold Time

t3

80

100

ns min

WR Pulse Width

t4

80

80

ns min

Data Valid to

WR

Setup Time

t54

10

10

ns min

Data Valid to

WR

Hold Time

t6

0

0

ns min

Address to WR Setup Time

t7

0

0

ns min

Address to

WR

Hold Time

t85

80

100

ns min

LDAC

Pulse Width

NOTES

1Sample tested at +25°C to ensure compliance. All input signals are specified with tr = tf = 5 ns (10% to 90% of 5 V) and timed from a voltage level of 1.6 V. 2See Figures 5 and 7.

3Power Supply tolerance is ±10% for A version and ±5% for B and T versions. 4If 0 ns < t2 < 10 ns, add t2 to t5. If t2 ³ 10 ns, add 10 ns to t5.

5AD7237A only.

ABSOLUTE MAXIMUM RATINGS1

(TA = +25°C unless otherwise noted)
VDD to GND (AD7247A) . . . . . . . . . . . . .	. . . –0.3 V to +17 V
VDD to AGND, DGND (AD7237A) . . . . .	. . . –0.3 V to +17 V
VDD to VSS . . . . . . . . . . . . . . . . . . . . . . . . . .	. . –0.3 V to +34 V
AGND to DGND (AD7237A) . . . . . . . . .	–0.3 V, VDD +0.3 V

VOUTA,2 VOUTB2 to AGND (GND) . . VSS –0.3 V to VDD +0.3 V

REF OUT to AGND (GND) . . . . . . . .	. . . .	. . . . . 0 V to VDD
REF IN to AGND (GND) . . . . . . . . . .	–0.3 V to VDD +0.3 V
Digital Inputs to DGND (GND) . . . . . .	–0.3 V to VDD +0.3 V
Operating Temperature Range		–40°C to +85°C
Industrial (A, B Versions) . . . . . . . . . .	. . .
Extended (T Version) . . . . . . . . . . . . .	. .	–55°C to +125°C
Storage Temperature Range . . . . . . . . . .	. .	–65°C to +150°C
Lead Temperature (Soldering, 10 secs) . .	. . .	. . . . . . . +300°C
Power Dissipation (Any Package) to +75°C . .		. . . . . 1000 mW
Derates above +75°C by . . . . . . . . . . . . .	. . .	. . . . . 10 mW/°C

NOTES

1Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

2Short-circuit current is typically 80 mA. The outputs may be shorted to voltages in this range provided the power dissipation of the package is not exceeded.

ORDERING GUIDE

		Relative
	Temperature	Accuracy	Package
Model1	Range	(LSB)	Option2
AD7237AAN	–40°C to +85°C	±1 max	N-24
AD7237ABN	–40°C to +85°C	±1/2 max	N-24
AD7237AAR	–40°C to +85°C	±1 max	R-24
AD7237ABR	–40°C to +85°C	±1/2 max	R-24
AD7237ATQ	–55°C to +125°C	±1/2 max	Q-24
AD7247AAN	–40°C to +85°C	±1 max	N-24
AD7247ABN	–40°C to +85°C	±1/2 max	N-24
AD7247AAR	–40°C to +85°C	±1 max	R-24
AD7247ABR	–40°C to +85°C	±1/2 max	R-24
AD7247ATQ	–55°C to +125°C	±1/2 max	Q-24

NOTES

1To order MIL-STD-883, Class B processed parts, add /883B to part number. Contact local sales office for military data sheet and availability.

2N = Plastic DIP; Q = Cerdip; R = Small Outline (SOIC).

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD7237A/AD7247A features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.

WARNING!

ESD SENSITIVE DEVICE

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AD7237A/AD7247A

						AD7237A PIN FUNCTION DESCRIPTION (DIP PIN NUMBERS)
Pin		Mnemonic				Description
1		REF INA				Voltage Reference Input for DAC A. The reference voltage for DAC A is applied to this pin. It is internally
						buffered before being applied to the DAC. The nominal reference voltage for correct operation of the
						AD7237A is 5 V.
2		REF OUT				Voltage Reference Output. The internal 5 V analog reference is provided at this pin. To operate the part with
						internal reference, REF OUT should be connected to REF INA, REF INB.
3		REF INB				Voltage Reference Input for DAC B. The reference voltage for DAC B is applied to this pin. It is internally
						buffered before being applied to the DAC. The nominal reference voltage for correct operation of the
						AD7237A is 5 V.
4		ROFSB				Output Offset Resistor for DAC B. This input configures the output ranges for DAC B. It is connected to
						VOUTB for the +5 V range, to AGND for the +10 V range and to REF INB for the ±5 V range.
5		VOUTB				Analog Output Voltage from DAC B. This is the buffer amplifier output voltage. Three different output
						voltage ranges can be chosen: 0 V to +5 V, 0 V to +10 V and ±5 V. The amplifier is capable of developing
						+10 V across a 2 kΩ resistor to GND.
6		AGND				Analog Ground. Ground reference for DACs, reference and output buffer amplifiers.
7		DB7				Data Bit 7.
8-10	DB6-DB4					Data Bit 6 to Data Bit 4.
11		DB3				Data Bit 3/Data Bit 11 (MSB).
12		DGND				Digital Ground. Ground reference for digital circuitry.
13		DB2				Data Bit 2/Data Bit 10.
14		DB1				Data Bit 1/Data Bit 9.
15		DB0				Data Bit 0 (LSB)/Data Bit 8.
16		A0				Address Input. Least significant address input for input latches. A0 and A1 select which of the four input
						latches data is written to (see Table II).
17		A1				Address Input. Most significant address input for input latches.
18						Chip Select. Active low logic input. The device is selected when this input is active.
		CS
19						Write Input.		is an active low logic input which is used in conjunction with		, A0 and A1 to write data
		WR					WR		CS
						to the input latches.
20						Load DAC. Logic input. A new word is loaded into the DAC latches from the respective input latches on the
		LDAC
						falling edge of this signal.
21		VDD				Positive Supply (+12 V to +15 V).
22		VOUTA				Analog Output Voltage from DAC A. This is the buffer amplifier output voltage. Three different output
						voltage ranges can be chosen: 0 V to +5 V, 0 V to +10 V and ±5 V. The amplifier is capable of developing
						+10 V across a 2 kΩ resistor to GND.
23		VSS				Negative Supply (0 V or –12 V to –15 V).
24		ROFSA				Output Offset Resistor for DAC A. This input configures the output ranges for DAC A. It is connected to
						VOUTA for the +5 V range, to AGND for the +10 V range and to REF INA for the ±5 V range.

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