AD2S44TM14B Analog Devices Inc, AD2S44TM14B Datasheet - Page 8

• Manufacturer Part Number: AD2S44TM14B
• Description: IC SYNC-R/D CONV 14BIT 2CH 32DIP
• Manufacturer: Analog Devices Inc
• Type: R/D Converterr

Specifications of AD2S44TM14B

• Rohs Status: RoHS non-compliant
• Resolution (bits): 14 b
• Data Interface: Parallel
• Voltage Supply Source: Dual ±
• Voltage - Supply: ±14.25 V ~ 15 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: 32-CDIP (0.900", 22.86mm)
• Sampling Rate (per Second): -

AD2S44
OUTPUT ENABLE (OE)
OE is the output enable input; the signal is active low. When set
to Logic 1, DB1 to DB14 are in high impedance state. When OE
is set to Logic 0, DB1 to DB14 represent the angle of the transducer
shaft to within the stated accuracy of the converter (see bit weights
in
Timing information is shown in
detailed in
Table 4. Bit Weight
Bit No.
1 (MSB)
2
3
4
5
6
7
8
9
10
11
12
13
14 ( LSB)
(1 TO 14)
(1 TO 14)
Table 4
DATA
*CONVERTER DATA OUTPUT IS INHIBITED FROM UPDATES
BITS
DATA
DURING CHANNEL VALID.
*CONVERTER DATA OUTPUT IS INHIBITED FROM UPDATES
BITS
A/B
OE
DURING CHANNEL VALID.
A/B
OE
). Data becomes valid 640 ns after the
Table 1
Figure 5. Alternative Reading of Each Channel
Figure 4. Repetitive Reading of One Channel
.
t
t
S
S
VALID*
DATA
CHANNEL B
Weight (Degrees)
180.0000
90.0000
45.0000
22.5000
11.2500
5.6250
2.8125
1.4063
0.7031
0.3516
0.1758
0.0879
0.0439
0.0220
VALID*
t
R
Figure 4
t
P
t
S
and
CHANNEL A
VALID*
VALID*
DATA
Figure 5
OE is switched.
t
R
and
Rev. A | Page 8 of 12
BUILT-IN TEST (BIT)
The BIT is the built-in test error output, which provides an over-
velocity or fault indication signal for the channel selected via A/ B .
The error voltage of each channel is continuously monitored. When
the error exceeds ±50 bits for the currently selected channel, the
BIT output goes low, indicating that an error greater than approx-
imately one angular degree exists, and the data is, therefore, invalid.
The BIT signal has a built-in hysteresis; that is, the error required to
set the BIT is greater than the error required for it to be cleared.
The BIT is set when the error exceeds 55 LSBs and is cleared when
the error goes below 45 LSBs. This mode of operation guarantees
that the BIT does not flicker when the error threshold is crossed.
The BIT is valid for the selected channel approximately 50 ns after
the change in the state of A/ B . In most instances, the error condi-
tion that sets the BIT must persist for at least one period of the
reference signal prior to the BIT responding to the condition.
Table 5. BIT Output Faults
Condition
Power-Up Transient
Response
Step Input > 1°
Excessive Velocity
Signal Failure
Converter/System
Failure
Description
The BIT returns to a logic high state after
the AD2S44 position output synchronizes
with the angle input to within 1°.
Normally, the BIT is low at power-up for
a period less than or equal to the large
signal step response settling time of the
AD2S44 after the ±V
stabilized to within 5% of their final values.
The BIT returns to a logic high state after
the selected channel of the AD2S44 has
settled to within 1° of the input angle
resulting from an instantaneous step.
The BIT is driven to a logic low if the
maximum tracking rate of the AD2S44 is
exceeded (20 rps typical).
The BIT may be driven to a logic low state if
all signal voltages to the selected channel
are lost.
Any failure that causes the AD2S44 to fail
to track the input synchro/resolver angles
drives the BIT to a logic low. This may
include, but is not limited to, acceleration
conditions, poor supply voltage regulation,
or excessive noise on the signal connections.
S
supplies have