Analog Devices DAC8512 a Datasheet

+5 V, Serial Input

7

8

1

2
3
4

5

6

REF 12-BIT DAC

DAC REGISTER

V

DD

V

OUT

GND

SERIAL REGISTER

12

12

CLR

LD

CS

CLK

SDI

a

FEATURES
Space Saving SO-8 or Mini-DIP Packages
Complete, Voltage Output with Internal Reference
1 mV/Bit with 4.095 V Full Scale
Single +5 Volt Operation
No External Components
3-Wire Serial Data Interface, 20 MHz Data Loading Rate
Low Power: 2.5 mW

APPLICATIONS
Portable Instrumentation
Digitally Controlled Calibration
Servo Controls
Process Control Equipment
PC Peripherals

GENERAL DESCRIPTION

The DAC8512 is a complete serial input, 12-bit, voltage output
digital-to-analog converter designed to operate from a single
+5 V supply. It contains the DAC, input shift register and
latches, reference and a rail-to-rail output amplifier. Built using
a CBCMOS process, these monolithic DACs offer the user low
cost, and ease of use in +5 V only systems.

Coding for the DAC8512 is natural binary with the MSB loaded
first. The output op amp can swing to either rail and is set to a
range of 0 V to +4.095 V—for a one-millivolt-per-bit resolution.
It is capable of sinking and sourcing 5 mA. An on-chip reference
is laser trimmed to provide an accurate full-scale output voltage
of 4.095 V.

Complete 12-Bit DAC

DAC8512

FUNCTIONAL BLOCK DIAGRAM

Serial interface is high speed, three-wire, DSP compatible with
data in (SDI), clock (CLK) and load strobe (LD). There is also
a chip-select pin for connecting multiple DACs.

A CLR input sets the output to zero scale at power on or upon
user demand.

The DAC8512 is specified over the extended industrial (–40°C
to +85°C) temperature range. DAC8512s are available in plas­tic DIPs and SO-8 surface mount packages.

1.0

0.75

0.5

0.25

0

–0.25

LINEARITY ERROR – LSB

–0.5

–0.75

–1.0

0

DIGITAL INPUT CODE – Decimal

307220481024

4096

Linearity Error vs. Digital Input Code

REV. A

Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 1996

DAC8512–SPECIFICATIONS

(@ V

ELECTRICAL CHARACTERISTICS

Parameter Symbol Condition Min Typ Max Units

STATIC PERFORMANCE

Resolution N Note 2 12 Bits
Relative Accuracy INL E Grade –1 ±1/4 +1 LSB

Differential Nonlinearity DNL No Missing Codes –1 ±3/4 +1 LSB
Zero-Scale Error V
Full-Scale Voltage V

Full-Scale Tempco TCV

ANALOG OUTPUT

Output Current I
Load Regulation at Full Scale L
Capacitive Load C

LOGIC INPUTS

Logic Input Low Voltage V
Logic Input High Voltage V
Input Leakage Current I
Input Capacitance C

INTERFACE TIMING SPECIFICATIONS

Clock Width High t
Clock Width Low t
Load Pulse Width t
Data Setup t
Data Hold t
Clear Pulse Width t
Load Setup t
Load Hold t
Select t
Deselect t

AC CHARACTERISTICS

4

Voltage Output Settling Time t
DAC Glitch 15 nV s
Digital Feedthrough 15 nV s

ZSE
FS

FS

OUT

REG
L

IL
IH

IL

IL

1, 4

CH
CL
LDW
DS
DH
CLRW
LD1
LD2
CSS
CSH

S

= +5.0 V 6 5%, –408C ≤ TA ≤ +858C, unless otherwise noted)

DD

F Grade –2 ±3/4 +2 LSB

Data = 000
Data = FFF

H

3

H

E Grade 4.087 4.095 4.103 V

+1/2 +3 LSB

F Grade 4.079 4.095 4.111 V

Notes 3, 4 16 ppm/°C

Data = 800
R

= 402 Ω to ∞, Data = 800

L

No Oscillation

H

4

H

±5 ±7mA

1 3 LSB
500 pF

0.8 V

2.4 V

10 µA
10 pF

30 10 ns
30 10 ns
20 ns
15 10 ns
15 5 ns
30 20 ns
15 ns
10 ns
30 ns
20 ns

To ±1 LSB of Final Value

5

16 µs

SUPPLY CHARACTERISTICS

Positive Supply Current I

Power Dissipation P

DD

DISS

VIH = 2.4 V, VIL = 0.8 V, No Load 1.5 2.5 mA
V

= 5 V, VIL = 0 V, No Load 0.5 1 mA

DD

VIH = 2.4 V, VIL = 0.8 V, No Load 7.5 12.5 mW
V

= 5 V, VIL = 0 V, No Load 2.5 5 mW

DD

Power Supply Sensitivity PSS ∆VDD = ±5% 0.002 0.004 %/%

NOTES

1

All input control signals are specified with tr = tf = 5 ns (10% to 90% of +5 V) and timed from a voltage level of 1.6 V.

2

1 LSB = 1 mV for 0 V to +4.095 V output range.

3

Includes internal voltage reference error.

4

These parameters are guaranteed by design and not subject to production testing.

5

The settling time specification does not apply for negative going transitions within the last 6 LSBs of ground. Some devices exhibit double the typical settling time in

this 6 LSB region.

Specifications subject to change without notice.

–2–

REV. A

DAC8512

WAFER TEST LIMITS

(@ VDD = +5.0 V 6 5%, TA = +258C, applies to part number DAC8512GBC only, unless otherwise noted)

Parameter Symbol Condition Min Typ Max Units

STATIC PERFORMANCE

Relative Accuracy INL –2 ± 3/4 +2 LSB
Differential Nonlinearity DNL No Missing Codes –1 ±0.7 +1 LSB
Zero-Scale Error V
Full-Scale Voltage V

ZSE
FS

Data = 000
Data = FFF

H

H

4.085 4.095 4.105 V

+1/2 +3 LSB

LOGIC INPUTS

Logic Input Low Voltage V
Logic Input High Voltage V
Input Leakage Current I

IL
IH

IL

2.4 V

0.8 V
10 µA

SUPPLY CHARACTERISTICS

Positive Supply Current I

Power Dissipation P

DD

DISS

VIH = 2.4 V, VIL= 0.8 V, No Load 1.5 2.5 mA
V

= 5 V, VIL = 0 V, No Load 0.5 1 mA

DD

VIH = 2.4 V, VIL = 0.8 V, No Load 7.5 12.5 mW
V

= 5 V, VIL = 0 V, No Load 2.5 5 mW

DD

Power Supply Sensitivity PSS ∆VDD = ±5% 0.002 0.004 %/%

NOTE
Electrical tests are performed at wafer probe to the limits shown. Due to variations in assembly methods and normal yield loss, yield after packaging is not guaranteed
for standard product dice. Consult factory to negotiate specifications based on dice lot qualifications through sample lot assembly and testing.

ABSOLUTE MAXIMUM RATINGS*

VDD to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V, +10 V

Logic Inputs to GND . . . . . . . . . . . . . . . –0.3 V, V

V

to GND . . . . . . . . . . . . . . . . . . . . . –0.3 V, VDD + 0.3 V

OUT

I

Short Circuit to GND . . . . . . . . . . . . . . . . . . . . . . 50 mA

OUT

Package Power Dissipation . . . . . . . . . . . . . .(T

Thermal Resistance θ

JA

+ 0.3 V

DD

max – T

J

)/θ

A

8-Pin Plastic DIP Package (P) . . . . . . . . . . . . . . . . 103°C/W

8-Lead SOIC Package (S) . . . . . . . . . . . . . . . . . . . 158°C/W

Maximum Junction Temperature (T

max) . . . . . . . . . +150°C

J

Operating Temperature Range . . . . . . . . . . . . .–40°C to +85°C

Storage Temperature Range . . . . . . . . . . . . .–65°C to +150°C

Lead Temperature (Soldering, 10 secs) . . . . . . . . . . . . +300°C

*Stresses above those listed under “Absolute Maximum Ratings” may cause

permanent damage to the device. This is a stress rating only and functional

JA

operation of the device at these or any other conditions above those indicated in the
operational sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability .

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 DAC8512 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.

ORDERING GUIDE

INL Temperature Package Package

Model (LSB) Range Description Option

DAC8512EP ±1 –40°C to +85°C 8-Pin P-DIP N-8
DAC8512FP ±2 –40°C to +85°C 8-Pin P-DIP N-8
DAC8512FS ±2 –40°C to +85° C 8-Lead SOIC SO-8
DAC8512GBC ±2 +25°C Dice

WARNING!

ESD SENSITIVE DEVICE

REV. A

–3–

DAC8512

SDI

CLK

CS

LD

SDI

CLK

LD

CLR

FS

V

OUT

ZS

D11 D10 D9 D8 D7 D6 D5 D3D4 D1D2 D0

t

css

t

ld1

t

t

ds

t

cl

dh

t

ch

t

ldw

t

s

±1 LSB
ERROR BAND

t

csh

t

ld2

t

clrw

t

S

Figure 1. Timing Diagram

CS

ESD PROTECTION DIODES TO VDD AND GND

CLK

DATA

SDI

SHIFT

REGISTER

Figure 2. Equivalent Clock Input Logic

Table I. Control-Logic Truth Table

CS2CLK2CLR LD Serial Shift Register Function DAC Register Function

H X H H No Effect Latched
L L H H No Effect Latched
L H H H No Effect Latched
L ↑+ H H Shift-Register-Data Advanced One Bit Latched
↑+ L H H Shift-Register-Data Advanced One Bit Latched
HX H↓– No Effect Updated with Current Shift Register Contents
H X H L No Effect Transparent
H X L X No Effect Loaded with All Zeros
HX ↑+ H No Effect Latched All Zeros

NOTES

l

↑+ positive logic transition; ↓– negative logic transition; X = Don’t Care.

2

CS and CLK are interchangeable.

3

Returning CS HIGH avoids an additional “false clock” of serial data input.

4

Do not clock in serial data while LD is LOW.

–4–

REV. A

DAC8512

R1

R2

V

OUT

RAIL-TO-RAIL
OUTPUT
AMPLIFIER

R

BANDGAP

REFERENCE

2R

R

2R

2R

2R

SPDT

N-CH FET

SWITCHES

2R

AV = 4.095/2.5
= 1.638V/V

VOLTAGE SWITCHED 12-BIT
R-2R D/A CONVERTER

BUFFER

2.5V

PIN CONFIGURATIONS

SO-8 P-DIP-8 & Cerdip-8

V

CS

CLK

SDI

DD

1

DAC8512

2

TOP VIEW

3

(Not to Scale)

4

V

OUT

8

GND

7

CLR

6

LD

5

V

CS

CLK

SDI

DD

1

2
3

(Not to Scale)

4

DAC8512

TOP VIEW

8

V

OUT

GND

7

CLR

6

LD

5

PIN DESCRIPTIONS

Pin Name Description

1VDDPositive Supply. Nominal value +5 V, ± 5%.

CS Chip Select. Active low input.

2
3 CLK Clock input for the internal serial input shift register.
4 SDI Serial Data Input. Data on this pin is clocked into the

internal serial register on positive clock edges of the
CLK pin. The Most Significant Bit (MSB) is loaded
first.

LD Active low input which writes the serial register data

5

into the DAC register. Asynchronous input.

CLR Active low digital input that clears the DAC register to

6

zero, setting the DAC to minimum scale. Asynchronous
input.

7 GND Analog ground for the DAC. This also serves as the

digital logic ground reference voltage.

8V

Voltage output from the DAC. Fixed output voltage

OUT

range of 0 V to 4.095 V with 1 mV/LSB. An internal
temperature stabilized reference maintains a fixed
full-scale voltage independent of time, temperature and
power supply variations.

OPERATION

The DAC8512 is a complete ready to use 12-bit digital-to-analog
converter. It contains a voltage-switched, 12-bit, laser-trimmed
DAC, a curvature-corrected bandgap reference, a rail-to-rail
output op amp, a DAC register, and a serial data input register.
The serial data interface consists of a CLK, serial data in (SDI),
and a load strobe (

LD). This basic 3-wire interface offers maxi­mum flexibility for interface to the widest variety of serial data
input loading requirements. In addition a
for multiple packaging loading and a power on reset

CS select is provided

CLR pin to

simplify start or periodic resets.

D/A CONVERTER SECTION

The DAC is a 12-bit voltage mode device with an output that
swings from GND potential to the 2.5 volt internal bandgap
voltage. It uses a laser trimmed R-2R ladder which is switched
by N channel MOSFETs. The output voltage of the DAC has a
constant resistance independent of digital input code. The DAC
output is internally connected to the rail-to-rail output op amp.

AMPLIFIER SECTION

The DAC’s output is buffered by a low power consumption pre­cision amplifier. This amplifier contains a differential PNP pair
input stage which provides low offset voltage and low noise, as
well as the ability to amplify the zero-scale DAC output volt­ages. The rail-to-rail amplifier is configured in a gain of 1.6384
(= 4.095 V/2.5 V) in order to set the 4.095 volt full-scale output
(1 mV/LSB). See Figure 3 for an equivalent circuit schematic of
the analog section.

DICE CHARACTERISTICS

2

CS

3

CLK

SUBSTRATE IS COMMON WITH VDD.

NUMBER OF TRANSISTORS: 642
DIE SIZE: 0.055 inch × 0.106 inch; 5830 sq mils

V

DD

1

4

SDI LD

V

OUT

8

GND

7

GND

7
6

CLR

Figure 3. Equivalent DAC8512 Schematic of Analog
Portion

The op amp has a 16 µs typical settling time to 0.01%. There
are slight differences in settling time for negative slowing signals

5

vs. positive. See the oscilloscope photos in the typical perfor­mances section of this data sheet.

REV. A

–5–

DAC8512

OUTPUT SECTION

The rail-to-rail output stage of this amplifier has been designed
to provide precision performance while operating near either
power supply.

V

DD

P-CH

V

N-CH

OUT

AGND

Figure 4. Equivalent Analog Output Circuit

Figure 4 shows an equivalent output schematic of the rail-to-rail
amplifier with its N channel pull down FETs that will pull an
output load directly to GND. The output sourcing current is
provided by a P channel pull up device that can supply GND
terminated loads, especially at the low supply tolerance values of

4.75 volts. Figures 5 and 6 provide information on output swing
performance near ground and full-scale as a function of load. In
addition to resistive load driving capability the amplifier has also
been carefully designed and characterized for up to 500 pF ca­pacitive load driving capability.

POWER SUPPLY

The very low power consumption of the DAC8512 is a direct
result of a circuit design optimizing use of the CBCMOS pro­cess. By using the low power characteristics of the CMOS for
the logic, and the low noise, tight matching of the complemen­tary bipolar transistors good analog accuracy is achieved.

For power consumption sensitive applications it is important to
note that the internal power consumption of the DAC8512 is
strongly dependent on the actual logic input voltage levels
present on the SDI,

CS, LD, and CLR pins. Since these inputs
are standard CMOS logic structures they contribute static
power dissipation dependent on the actual driving logic V
V

voltage levels. The graph in Figure 9 shows the effect on to-

OL

OH

and

tal DAC8512 supply current as a function of the actual value of
input logic voltage. Consequently use of CMOS logic vs. TTL
minimizes power dissipation in the static state. A V
the SDI,

CS and CLR pins provides the lowest standby power

= 0 V on

IL

dissipation of 2.5 mW (500 µA × 5 V).

As with any analog system, it is recommended that the DAC8512
power supply be bypassed on the same PC card that contains the
chip. Figure 10 shows the power supply rejection versus frequen­cy performance. This should be taken into account when using
higher frequency switched mode power supplies with ripple fre­quencies of 100 kHz and higher.

One advantage of the rail-to-rail output amplifier used in the
DAC8512 is the wide range of usable supply voltage. The part
is fully specified and tested over temperature for operation from
+4.75 V to +5.25 V. If reduced linearity and source current ca­pability near full scale can be tolerated, operation of the DAC8512
is possible down to +4.3 volts. The minimum operating supply
voltage versus load current plot, in Figure 11, provides informa­tion for operation below V

TIMING AND CONTROL

= +4.75 V.

DD

The DAC8512 has a separate serial input register from the
12-bit DAC register that allows preloading of a new data value
into the serial register without disturbing the present DAC out­put voltage. After the new value is fully loaded in the serial in­put register it can be asynchronously transferred to the DAC
register by strobing the
sensitive

LD strobe that should be returned high before any

LD pin. The DAC register uses a level

new data is loaded into the serial input register. At any time the
contents of the DAC register can be reset to zero by strobing
the

CLR pin which causes the DAC output voltage to go to
zero volts. All of the timing requirements are detailed in Figure
1 along with the Table I Control-Logic Truth Table.

–6–

REV. A