hi5905n Intersil Corporation, hi5905n Datasheet - Page 5

• Manufacturer Part Number: hi5905n
• Description: 14-bit, 5 Msps, Military A/d Converter
• Manufacturer: Intersil Corporation

identical four-bit subconverter stages with the corresponding
output of the fifth stage flash converter before applying the
twenty bit result to the digital error correction logic. The
digital error correction logic uses the supplementary bits to
correct any error that may exist before generating the final
fourteen bit digital data output of the converter.
Because of the pipeline nature of this converter, the digital
data representing an analog input sample is output to the
digital data bus on the 4th cycle of the clock after the analog
sample is taken. This time delay is specified as the data
latency. After the data latency time, the digital data
representing each succeeding analog sample is output
during the following clock cycle. The digital output data is
synchronized to the external sampling clock with a latch. The
digital output data is available in two’s complement binary
format (see Table 1, A/D Code Table).
Internal Reference Generator, V
The HI5905 has an internal reference generator, therefore, no
external reference voltage is required. V
connected to V
The HI5905 can be used with an external reference. The
converter requires only one external reference voltage
connected to the V
The HI5905 is tested with V
to V
1.3V and 3.3V are generated for a fully differential input
signal range of 2V.
In order to minimize overall converter noise, it is
recommended that adequate high frequency decoupling be
provided at the reference voltage input pin, V
Analog Input, Differential Connection
The analog input to the HI5905 can be configured in various
ways depending on the signal source and the required level
of performance. A fully differential connection (Figure 4) will
give the best performance for the converter.
Since the HI5905 is powered off a single +5V supply, the
analog input must be biased so it lies within the analog input
+Full Scale
(+FS) - 1/4 LSB
+FS
-FS + 1 3/4 LSB
-Full Scale
(-FS) + 3/4 LSB
†
+ 3/4 LSB
- 1/4 LSB
DESCRIPTION
The voltages listed above represent the ideal center of each two’s complement binary output code shown.
RIN
CENTER
-
CODE
1 1/4 LSB
. Internal to the converter, two reference voltages of
RIN
INPUT VOLTAGE
+1.99994V
1.99969V
183.105 V
-61.035 V
-1.99957V
-1.99982V
(USING INTERNAL
when using the internal reference voltage.
RIN
DIFFERENTIAL
REFERENCE)
pin with V
ROUT
4-5
ROUT
, equal to 4.0V, connected
†
MSB
D13
ROUT
0
0
0
1
1
1
ROUT
left open.
D12
and V
RIN
1
1
0
1
0
0
must be
.
D11
RIN
TABLE 1. A/D CODE TABLE
1
1
0
1
0
0
D10
1
1
0
1
0
0
TWO’S COMPLEMENT BINARY OUTPUT CODE
D9
1
1
0
1
0
0
common mode voltage range of 1.0V to 4.0V. The
performance of the ADC does not change significantly with
the value of the analog input common mode voltage.
A 2.3V DC bias voltage source, V
top and bottom internal reference voltages, is made
available to the user to help simplify circuit design when
using a differential input. This low output impedance voltage
source is not designed to be a reference but makes an
excellent bias source and stays within the analog input
common mode voltage range over temperature.
The difference between the converter’s two internal voltage
references is 2V. For the AC coupled differential input, (Figure
4), if V
phase with V
bias voltage equal to V
on a DC bias voltage equal to V
will be at positive full scale, resulting in a digital data output code
with D13 (MSB) equal to a logic “0” and D0-D12 equal to logic
“1” (see Table 1, A/D Code Table), when the V
V
Conversely, the ADC will be at negative full scale, resulting in a
digital data output code with D13 (MSB) equal to a logic “1” and
D0-D12 equal to logic “0” (see Table 1, A/D Code Table), when
the V
(V
peak-to-peak differential analog input voltage range of 2V .
The analog input can be DC coupled (Figure 5) as long as
the inputs are within the analog input common mode voltage
range (1.0V
DC
D8
IN
1
1
0
1
0
0
+-V
+1V and the V
IN
IN
+ input is equal to V
FIGURE 4. AC COUPLED DIFFERENTIAL INPUT
IN
is a 2V
D7
-V
1
1
0
1
0
0
- = -2V). From this, the converter is seen to have a
V
IN
IN
IN
, then V
VDC
P-P
D6
1
1
0
1
0
0
IN
sinewave with -V
- input is at VDC-1V (V
IN
DC
4.0V).
D5
1
1
0
1
0
0
+ is a 2V
and V
DC
-1V and V
D4
DC
1
1
0
1
0
0
IN
P-P
- is a 2V
. Consequently, the converter
DC
IN
D3
sinewave riding on a DC
1
1
0
1
0
0
, half way between the
being 180 degrees out of
IN
- is at V
P-P
IN
D2
V
V
V
1
1
0
1
0
0
IN
+ - V
IN
DC
IN
sinewave riding
+
-
+ input is at
HI5905
DC
IN
D1
1
1
0
1
0
0
- = 2V).
+1V
LSB
D0
1
0
0
1
1
0