HI3-7159A-5 Intersil, HI3-7159A-5 Datasheet - Page 6

• Manufacturer Part Number: HI3-7159A-5
• Description: CONV A/D 5.5 DIGITIC MPU 28-DIP
• Manufacturer: Intersil

Specifications of HI3-7159A-5

• Number Of Bits: 8
• Sampling Rate (per Second): 200k
• Data Interface: Serial, Parallel
• Number Of Converters: 1
• Voltage Supply Source: Analog and Digital, Dual ±
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 28-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Theory of Operation
The HI-7159A attains its 5
of multiple integrations per conversion, creating an effective
integrator swing greater than the supply rails, and a
successive integration technique used to measure the
residue on the integrator capacitor to 5
In the 5
reference de-integrated four times. This results in a count with
the same effective resolution as a single integration with four
times the integrator swing amplitude. In this manner effective
integrator swings of 12V or greater can be achieved with 5V
supplies. The four integrations are spaced so that common-
mode signals whose frequency is an integer multiple of
f
input integration is performed, thus the minimum frequency for
common-mode rejection becomes f
These first four integrations measure the input voltage to an
resolution of 3
accuracy (10 V/count), the error voltage remaining on the
integrator capacitor (representing the overshoot of the
integrator due to comparator delay and clock quantization)
must be measured and subtracted from the 3
This is accomplished by multiplying the residue by a factor of
10, then integrating and reference de-integrating the error.
This error is subtracted from the 3
4
is then multiplied by 10 and subtracted, and the process is
repeated a third time to achieve an internal accuracy of 6
digits. This result is rounded to 5
the holding register, where it can be accessed by the user
through one of the three communications modes.
Conversion Types
The HI-7159A offers the user a choice of three different
conversion types. They are: (1) the converter’s internal offset
voltage, measured by internally connecting V
to A
input voltage (V
internal offset (Uncompensated Mode); and (3) the input
voltage including internal offset errors, minus the internal offset
errors (Compensated Mode). This last measurement is a digital
subtraction of an Error Only conversion from an
Uncompensated conversion, and is the default conversion type.
Since a Compensated conversion consists of two conversions,
it takes twice as long to perform as the first two types.
Under some conditions, it may be desirable to increase the
conversion rate without loss of resolution or accuracy. Since
the short term drift of the internal offset error is slight when
temperature is controlled, it is not always necessary to
convert the error voltage once for every input voltage
conversion. It is possible for the host processor to do an
error conversion periodically, store the result, and subtract
the error from a stream of uncompensated input conversions
with its own internal ALU. In this way the conversion rate can
be effectively doubled.
CRYSTAL
1
/
2
GND
digit accurate result. The error remaining from this step
1
/
and doing a conversion (Error Only Mode); (2) the
2
/40,000 are rejected. In the 4
digit mode, the input voltage is integrated and
1
IN HI
/
2
digits, or 1mV/count. To achieve 5
minus V
1
/
2
IN LO
digit resolution through the use
6
1
) including the converter’s
/
CRYSTAL
1
2
/
2
digits and transferred to
1
digit result, yielding a
/
1
2
/
digit mode, only one
2
digit accuracy.
/10,000.
IN HI
1
/
2
and V
digit result.
1
/
2
IN LO
digit
1
/
HI-7159A
2
Communication Modes
The HI-7159A A/D converter receives instructions from and
transmits data to the user host processor through one of four
communication modes. The modes are: parallel
microprocessor (Parallel); synchronous serial (Serial Mode 0);
serial non-addressed (Serial Mode 1); and serial addressed
(Serial Mode 2). The mode is determined by the states of the
SEL, SMS0, and SMS1 pins as shown in Table 1.
The parallel mode allows the converter to be attached directly
to a microprocessor data bus. Data is read and written to the
device under control of the microprocessor’s RD, WR and CS
signals. Serial Mode 0 permits high speed serial data transfer
at up to 1 megabits/s. Serial Mode 1 reads and writes industry
standard serial data packets consisting of 1 start bit, 8 data
bits, 1 parity bit (EVEN), and 1 stop bit, at one of 4 hardware
selectable baud rates. Serial Mode 2 is identical to Serial
Mode 1 with the addition of addressing capabilities which
allow up to 32 HI-7159As to share the same serial line, with
each assigned a unique address.
All four modes follow the same interface protocol: a request
or a command is sent from the host to the HI-7159A, and the
converter responds with the requested data and, in the case
of a command, begins a new conversion.
Parallel Mode Operation
The parallel communication mode (Figure 3) is selected
when SEL (Pin 28) is high. Pins 18-25 become the eight
bidirectional data bits, P0-P7. Pins 15, 16, and 17
respectively become read (RD), write (WR), and chip select
(CS). Timing parameters for the parallel mode are shown in
Figure 1.
Serial Mode 0
Serial Mode 0 is the high speed synchronous serial interface,
directly compatible with the MCS-51 series of microcontrollers.
It is enabled by tying SEL (Pin 28), SMS0 (Pin 18) and SMS1
(Pin 19) low (Figure 4A). Pin 16 is the bidirectional serial data
path, and pin 15 is the data clock input. Data sent to the
HI-7159A is latched on the rising edge of the serial clock. See
Figure 2A for detailed timing information.
Only 8 data bits are used in this mode - no start, stop, or
parity bits are transmitted or received. CS must either be tied
to D
SAD0 - SAD3 and BRS0 - BRS1 pins are unused in this
mode and should be tied high.
Parallel
Serial 0
Serial 1
Serial 2
COMMUNICATION MODE
GND
TABLE 1. COMMUNICATION MODE SELECTION
or pulled low to access the device. The
SEL PIN
D
D
D
V
GND
GND
GND
28
CC
PIN 18
SM S0
D
D
V
N/A
GND
GND
CC
SM S1
PIN 19
D
D
V
N/A
GND
GND
CC