4 or 8 Analog Input Channels
Built-In Track-and-Hold Function
10 kHz Signal Handling on Each Channel
Fast Microprocessor Interface
Single 5 V Supply
Low Power: 50 mW
Fast Conversion Rate: 2.5 s/Channel
Tight Error Specification: 1/2 LSB
The AD7824 and AD7828 are high speed, multichannel, 8-bit
ADCs with a choice of four (AD7824) or eight (AD7828) multi-
plexed analog inputs. A half-flash conversion technique gives a fast
conversion rate of 2.5 µs per channel, and the parts have a built-in
track-and-hold function capable of digitizing full-scale signals of
10 kHz (157 mV/µs slew rate) on all channels. The AD7824 and
AD7828 operate from a single 5 V supply and have an analog input
range of 0 V to 5 V, using an external 5 V reference.
Microprocessor interfacing of the parts is simple, using standard
Chip Select (CS) and Read (RD) signals to initiate the conversion
and read the data from the three-state data outputs. The half-flash
conversion technique means that there is no need to generate a
clock signal for the ADC. The AD7824 and AD7828 can be
interfaced easily to most popular microprocessors.
The AD7824 and AD7828 are fabricated in an advanced, all
ion-implanted, linear compatible CMOS process (LC
have low power dissipation of 40 mW (typ). The AD7824 is
available in a 0.3" wide, 24-lead “skinny” DIP, while the AD7828
is available in a 0.6" wide, 28-lead DIP and in 28-terminal surface-
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may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
4- and 8-Channel 8-Bit ADCs
FUNCTIONAL BLOCK DIAGRAM
A0 A1 A2**
*AD7824 – 4-CHANNEL MUX
**AD7828 – 8-CHANNEL MUX
A2 – AD7828 ONLY
1. 4- or 8-channel input multiplexer gives cost effective,
space-saving multichannel ADC system.
2. Fast conversion rate of 2.5 µs/channel features a per-channel
sampling frequency of 100 kHz for the AD7824 or 50 kHz
for the AD7828.
3. Built-in track-and-hold function allows handling of four or
eight channels up to 10 kHz bandwidth (157 mV/µs slew rate).
4. Tight total unadjusted error spec and channel-to-channel
matching eliminate the need for user trims.
5. Single 5 V supply simplifies system power requirements.
6. Fast, easy-to-use digital interface allows connection to most
popular microprocessors with minimal external components.
No clock signal is required for the ADC.
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MOS High Speed
TIMING AND CONTROL