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PDF AD7810 Data sheet ( Hoja de datos )
| Número de pieza | AD7810 | |
| Descripción | 10-Bit ADC | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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FEATURES
10-Bit ADC with 2.3 s Conversion Time
Small Footprint 8-Lead microSOIC Package
Specified Over a –40؇C to +105؇C Temperature Range
Inherent Track-and-Hold Functionality
Operating Supply Range: 2.7 V to 5.5 V
Specifications at 2.7 V to 5.5 V
Microcontroller-Compatible Serial Interface
Optional Automatic Power-Down
at End of Conversion
Low Power Operation
270 W at 10 kSPS Throughput Rate
2.7 mW at 100 kSPS Throughput Rate
Analog Input Range: 0 V to VREF
Reference Input Range: 0 V to VDD
APPLICATIONS
Low Power, Hand-Held Portable Applications that
Require Analog-to-Digital Conversion with 10-Bit
Accuracy; e.g., Battery Powered Test Equipment,
Battery-Powered Communications Systems
2.7 V to 5.5 V, 2.3 s, 10-Bit
ADC in 8-Lead microSOIC/DIP
AD7810
FUNCTIONAL BLOCK DIAGRAM
VDD AGND
VREF
AD7810
CHARGE
REDISTRIBUTION
DAC
VIN+
VIN–
CLOCK
OSC
VDD/3
COMP
SERIAL
PORT
DOUT
SCLK
CONTROL
LOGIC
CONVST
GENERAL DESCRIPTION
The AD7810 is a high speed, low power, 10-bit A/D con-
verter that operates from a single 2.7 V to 5.5 V supply. The
part contains a 2.3 µs successive approximation A/D converter,
with inherent track/hold functionality, a pseudo differential
input and a high speed serial interface that interfaces to most
microcontrollers. The AD7810 is fully specified over a tem-
perature range of –40°C to +105°C.
By using a technique that samples the state of the CONVST
(convert start) signal at the end of a conversion, the AD7810
may be used in an automatic power-down mode. When used in
this mode, the AD7810 automatically powers down at the end
of a conversion and “wakes up” at the start of a new conversion.
This feature significantly reduces the power consumption of the
part at lower throughput rates. The AD7810 can also operate in
a high speed mode where the part is not powered down between
conversions. In this high speed mode of operation, the conver-
sion time of the AD7810 is 2.3 µs. The maximum throughput
rate is dependent on the speed of the serial interface of the
microcontroller.
The part is available in a small 8-lead, 0.3" wide, plastic dual-
in-line package (mini-DIP); in an 8-lead, small outline IC
(SOIC); and in an 8-lead microSOIC package.
PRODUCT HIGHLIGHTS
1. Complete, 10-Bit ADC in 8-Lead Package
The AD7810 is a 10-bit 2.3 µs ADC with inherent track/hold
functionality and a high speed serial interface—all in an
8-lead microSOIC package. VREF may be connected to VDD
to eliminate the need for an external reference. The result is
a high speed, low power, space saving ADC solution.
2. Low Power, Single Supply Operation
The AD7810 operates from a single 2.7 V to 5.5 V supply
and typically consumes only 9 mW of power while convert-
ing. The power dissipation can be significantly reduced at
lower throughput rates by using the automatic power-down
mode, e.g., at a throughput rate of 10 kSPS the power
consumption is only 270 µW.
3. Automatic Power-Down
The automatic power-down mode, whereby the AD7810
powers down at the end of a conversion and “wakes up”
before the next conversion, means the AD7810 is ideal for
battery powered applications. See Power vs. Throughput
Rate section.
4. Serial Interface
An easy to use, fast serial interface allows connection to most
popular microprocessors with no external circuitry.
REV. B
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: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2000
1 page  
AD7810
Pin No.
1
Mnemonic
CONVST
2 VIN+
3 VIN–
4 GND
5 VREF
6 DOUT
7 SCLK
8 VDD
PIN FUNCTION DESCRIPTIONS
Description
Convert Start. Falling edge puts the track-and-hold into hold mode and initiates a conversion.
A rising edge on the CONVST pin enables the serial port of the AD7810. This is useful in multi-
package applications where a number of devices share the same serial bus. The state of this pin at
the end of conversion also determines whether the part is powered down or not. See Operating
Modes section of this data sheet.
Positive input of the pseudo differential analog input.
Negative input of the pseudo differential analog input.
Ground reference for analog and digital circuitry.
External reference is connected here.
Serial data is shifted out on this pin.
Serial Clock. An external serial clock is applied here.
Positive Supply Voltage 2.7 V to 5.5 V.
PIN CONFIGURATION
DIP/SOIC
CONVST 1
8 VDD
VIN+ 2 AD7810 7 SCLK
VIN–
3
TOP VIEW
(Not to Scale)
6
DOUT
GND 4
5 VREF
Typical Performance Characteristics
10
1
0.1
0.01
0
10 20 30 40
THROUGHPUT – kSPS
Figure 2. Power vs. Throughput
50
–15
–35
–55
–75
–95
–115
2048 POINT FFT
SAMPLING 357.142kSPS
FIN = 30kHz
FREQUENCY BINS
Figure 3. AD7810 SNR
–4– REV. B
5 Page 
AD7810
MICROPROCESSOR INTERFACING
The serial interface on the AD7810 allows the parts to be directly
connected to a range of many different microprocessors. This
section explains how to interface the AD7810 with some of the
more common microcontroller serial interface protocols.
AD7810 to PIC16C6x/7x
The PIC16C6x Synchronous Serial Port (SSP) is configured
as an SPI Master with the Clock Polarity Bit = 0. This is done
by writing to the Synchronous Serial Port Control Register
(SSPCON). See PIC16/17 Microcontroller User Manual. Figure
17 shows the hardware connections needed to interface to the
PIC16/PIC17. In this example I/O port RA1 is being used to
pulse CONVST and enable the serial port of the AD7810. This
microcontroller transfers only eight bits of data during each
serial transfer operation, therefore, two consecutive read opera-
tions are needed.
AD7810*
SCLK
DOUT
CONVST
PIC16C6x/7x*
SCK/RC3
SDO/RC5
RA1
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 17. Interfacing to the PIC16/PIC17
AD7810 to MC68HC11
The Serial Peripheral Interface (SPI) on the MC68HC11 is
configured for Master Mode (MSTR = 0), Clock Polarity Bit
(CPOL) = 0, and the Clock Phase Bit (CPHA) = 1. The SPI is
configured by writing to the SPI Control Register (SPCR)—see
68HC11 User Manual. A connection diagram is shown in
Figure 18.
AD7810 to 8051
The AD7810 requires a clock synchronized to the serial data;
therefore, the 8051 serial interface must be operated in Mode
0. In this mode serial data enters and exits through RXD, and a
serial clock is output on TXD (half duplex). Figure 19 shows
how the 8051 is connected to the AD7810. However, because
the AD7810 shifts data out on the rising edge of the serial
clock, the serial clock must be inverted.
AD7810*
SCLK
DOUT
CONVST
TXD
RXD
P1.1
8051*
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 19. Interfacing to the 8051 Serial Port
It is possible to implement a serial interface using the data ports
on the 8051 (or any microcontroller). This would allow direct
interfacing between the AD7810 and 8051 to be implemented.
The technique involves “bit banging” an I/O port (e.g., P1.0)
to generate a serial clock and using another I/O port (e.g., P1.1)
to read in data, see Figure 20.
AD7810*
SCLK
DOUT
CONVST
P1.0
P1.1
P1.2
8051*
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 20. Interfacing to the 8051 Using I/O Ports
AD7810*
SCLK
DOUT
CONVST
MC68HC11*
SCLK/PD4
MISO/PD2
PA0
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 18. Interfacing to the MC68HC11
–10–
REV. B
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet AD7810.PDF ] | |
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