Analog Devices AD7813 c Datasheet

2.7 V to 5.5 V, 400 kSPS

a

FEATURES
8-/10-Bit ADC with 2.3 s Conversion Time
On-Chip Track and Hold
Operating Supply Range: 2.7 V to 5.5 V
Specifications at 2.7 V– 3.6 V and 5 V  10%
8-Bit Parallel Interface

8-Bit + 2-Bit Read

Power Performance

Normal Operation

10.5 mW, V

Automatic Power-Down

34.6 W @ 1 kSPS, V
Analog Input Range: 0 V to V
Reference Input Range: 1.2 V to V

GENERAL DESCRIPTION

The AD7813 is a high-speed, microprocessor-compatible,
8-/10-bit analog-to-digital converter with a maximum through­put of 400 kSPS. The converter operates off a single 2.7 V to

5.5 V supply and contains a 2.3 µs successive approximation
A/D converter, track/hold circuitry, on-chip clock oscillator and
8-bit wide parallel interface. The parallel interface is designed to
allow easy interfacing to microprocessors and DSPs. The 10-bit
conversion result is read by carrying out two 8-bit read opera­tions. The first read operation accesses the 8 MSBs of the ADC
conversion result and the second read accesses the 2 LSBs.
Using only address decoding logic the AD7813 is easily mapped
into the microprocessor address space.

When used in its power-down mode, the AD7813 automatically
powers down at the end of a conversion and powers up at the
start of a new conversion. This feature significantly reduces the
power consumption of the part at lower throughput rates. The
AD7813 can also operate in a high speed mode where the part is
not powered down between conversions. In this mode of opera­tion the part is capable of providing 400 kSPS throughput.

The part is available in a small, 16-lead, 0.3" wide, plastic dual­in-line package (DIP), in a 16-lead, 0.15" wide, narrow body
small outline IC (SOIC) and in a 16-lead thin shrink small
outline package (TSSOP).

= 3 V

DD

= 3 V

DD

REF

DD

8-/10-Bit Sampling ADC

AD7813

FUNCTIONAL BLOCK DIAGRAM

V

AGND

DD

AD7813

V

T/H

IN

PRODUCT HIGHLIGHTS

1. Low Power, Single Supply Operation
The AD7813 operates from a single 2.7 V to 5.5 V supply
and typically consumes only 10.5 mW of power. The power
dissipation can be significantly reduced at lower through­put rates by using the automatic power-down mode.

2. Automatic Power-Down
The automatic power-down mode, whereby the AD7813
goes into power-down mode at the end of a conversion and
powers up before the next conversion, means the AD7813
is ideal for battery powered applications; e.g., 34.6 µW
@ 1 kSPS. (See Power vs. Throughput Rate section.)

3. Parallel Interface
An easy to use 8-bit-wide parallel interface allows interfacing
to most popular microprocessors and DSPs with minimal
external circuitry.

4. Dynamic Specifications for DSP Users
In addition to the traditional ADC specifications, the AD7813
is specified for ac parameters, including signal-to-noise ratio
and distortion.

V

REF

CHARGE

REDISTRIBUTION

DAC

CLOCK

OSC

COMP

BUSY

THREE-

STATE

DRIVERS

CONTROL

LOGIC

CS RD

DB7

DB0

CONVST

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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.

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Fax: [phone] © Analog Devices, Inc., 2000

AD7813–SPECIFICATIONS

(GND = 0 V, V

1

+105C unless otherwise noted.)

= VDD = 3 V  10% to 5 V  10%. All specifications –40C to

REF

Parameter Y Version Unit Test Conditions/Comments

DYNAMIC PERFORMANCE f

Signal to (Noise + Distortion) Ratio
Total Harmonic Distortion (THD)
Peak Harmonic or Spurious Noise
Intermodulation Distortion

2

1

1

1

58 dB min
–66 dB max
–66 dB max

= 30 kHz, f

IN

fa = 29.1 kHz, fb = 29.8 kHz
2nd Order Terms –67 dB typ
3rd Order Terms –67 dB typ

DC ACCURACY

Resolution 10 Bits
Minimum Resolution for Which

No Missing Codes Are Guaranteed 10 Bits

Relative Accuracy
Differential Nonlinearity (DNL)
Gain Error
Offset Error

1

1

1

1

± 1 LSB max
± 1 LSB max
± 2 LSB max
± 2.0 LSB max

ANALOG INPUT

Input Voltage Range 0 V min

V
Input Leakage Current
Input Capacitance

REFERENCE INPUTS

V

Input Voltage Range 1.2 V min

REF

2

2

2

REF

± 1 µA max

20 pF max

V

DD

V max

V max
Input Leakage Current ± 3 µA max
Input Capacitance 15 pF max

LOGIC INPUTS

V

Input High Voltage 2.0 V min

INH,

V

Input Low Voltage 0.4 V max (0.8 V max, VDD = 5 V)

INL,

Input Current, I
Input Capacitance, C

2

IN

IN

± 1 µA max Typically 10 nA, VIN = 0 V to V
8 pF max

LOGIC OUTPUTS

Output High Voltage, V
Output Low Voltage, V

OL

OH

2.4 V min I

0.4 V max I

SOURCE

= 200 µA

SINK

= 200 µA

High Impedance Leakage Current ± 1 µA max
High Impedance Capacitance 15 pF max

SAMPLE

= 350 kHz

DD

CONVERSION RATE

Conversion Time 2.3 µs max
Track/Hold Acquisition Time

1

100 ns max

POWER SUPPLY

V

DD

I

DD

2.7–5.5 Volts For Specified Performance

Normal Operation 3.5 mA max
Power-Down 1 µA max V

Power Dissipation

Normal Operation 17.5 mW max V
Power-Down 5 µW max
Auto Power-Down V

1 kSPS Throughput 34.6 µW max
10 kSPS Throughput 346.5 µW max
100 kSPS Throughput 3.46 mW max

NOTES

1

See Terminology section.

2

Sample tested during initial release and after any redesign or process change that may affect this parameter.

Specifications subject to change without notice.

–2–

Digital Inputs = 0 V or V

= 5 V

DD

= 5 V

DD

= 3 V

DD

DD

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1, 2

WARNING!

ESD SENSITIVE DEVICE

TIMING CHARACTERISTICS

(–40C to +105C, unless otherwise noted)

Parameter VDD = 3 V  10% VDD = 5 V  10% Unit Conditions/Comments

AD7813

t

POWER-UP

t

1

t

2

t

3

t

4

t

5

3

t

6

3, 4

t

7

1.5 1.5 µs (max) Power-Up Time of AD7813 after Rising Edge of CONVST.

2.3 2.3 µs (max) Conversion Time.
20 20 ns (min) CONVST Pulsewidth.
30 30 ns (max) CONVST Falling Edge to BUSY Rising Edge Delay.
0 0 ns (min) CS to RD Setup Time.
0 0 ns (min) CS Hold Time after RD High.
10 10 ns (max) Data Access Time after RD Low.
10 10 ns (max) Bus Relinquish Time after RD High.
5 5 ns (min)

t

8

3

t

9

NOTES

1

Sample tested to ensure compliance.

2

See Figures 12, 13 and 14.

3

These numbers are measured with the load circuit of Figure 1. They are defined as the time required for the o/p to cross 0.8 V or 2.4 V for VDD = 5 V ± 10% and

0.4 V or 2 V for VDD = 3 V ± 10%.

4

Derived from the measured time taken by the data outputs to change 0.5 V when loaded with the circuit of Figure 1. The measured number is then extrapolated back
to remove the effects of charging or discharging the 50 pF capacitor. This means that the time, t
of the part and as such is independent of external bus loading capacitances.

10 10 ns (min) Minimum Time Between MSB and LSB Reads.
50 50 ns (min) Rising Edge of CS or RD to Falling Edge of CONVST Delay.

, quoted in the Timing Characteristics is the true bus relinquish time

7

ABSOLUTE MAXIMUM RATINGS*

VDD to DGND . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V

200AI

OL

Digital Input Voltage to DGND

(CONVST, RD, CS) . . . . . . . . . . . . . . –0.3 V, V

Digital Output Voltage to DGND

(BUSY, DB0–DB7) . . . . . . . . . . . . . . . –0.3 V, V

to AGND . . . . . . . . . . . . . . . . . . . –0.3 V, V

REF

IN

Analog Input . . . . . . . . . . . . . . . . . . . . . . –0.3 V, V

+ 0.3 V

DD

+ 0.3 V

DD

+ 0.3 V

DD

+ 0.3 V

DD

OUTPUT

PIN

TO

50pF

C

L

200A

I

OH

1.6V

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

Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . 150°C

Plastic DIP Package, Power Dissipation . . . . . . . . . . 450 mW

Thermal Impedance . . . . . . . . . . . . . . . . . . . . 105°C/W

θ

JA

Figure 1. Load Circuit for Digital Output Timing
Specifications

Lead Temperature, (Soldering 10 sec) . . . . . . . . . . . . 260°C

SOIC Package, Power Dissipation . . . . . . . . . . . . . . . 450 mW

Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 75°C/W

θ

JA

Lead Temperature, Soldering

Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215°C

Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C

SSOP Package, Power Dissipation . . . . . . . . . . . . . . . 450 mW

Thermal Impedance . . . . . . . . . . . . . . . . . . . . 115°C/W

θ

JA

Lead Temperature, Soldering

Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215°C

Model Error Description Option

AD7813YN ± 1 LSB Plastic DIP N-16
AD7813YR ±1 LSB Small Outline IC R-16A
AD7813YRU ± 1 LSB Thin Shrink Small Outline RU-16

ORDERING GUIDE

Linearity Package Package

(TSSOP)

Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C

*Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; 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.

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 AD7813 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.

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–3–

AD7813

Pin
No. Mnemonic Description

PIN FUNCTION DESCRIPTIONS

1V
2V

REF

IN

Reference Input, 1.2 V to VDD.
Analog Input, 0 V to V

REF

.

3 GND Analog and Digital Ground.
4 CONVST Convert Start. A low-to-high transition on this pin initiates a 1.5 µs pulse on an internally generated

CONVST signal. A high-to-low transition on this line initiates the conversion process if the internal
CONVST signal is low. Depending on the signal on this pin at the end of a conversion, the AD7813

automatically powers down.

5 CS Chip Select. This is a logic input. CS is used in conjunction with RD to enable outputs.
6 RD Read Pin. This is a logic input. When CS is low and RD goes low, the DB7–DB0 leave their high

impedance state and data is driven onto the data bus.
7 BUSY ADC Busy Signal. This is a logic output. This signal goes logic high during the conversion process.
8–15 DB0–DB7 Data Bit 0 to 7. These outputs are three-state TTL-compatible.
16 V

DD

Positive power supply voltage, 2.7 V to 5.5 V.

PIN CONFIGURATION

DIP/SOIC

V

REF

V

GND

CONVST

CS

RD

BUSY

DB0

1

2

IN

3

4

5

6

7

8

AD7813

TOP VIEW

(Not to Scale)

V

16

DD

DB7

15

DB6

14

DB5

13

DB4

12

DB3

11

DB2

10

DB1

9

–4–

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