hi5905 Intersil Corporation, hi5905 Datasheet - Page 8

• Manufacturer Part Number: hi5905
• Description: 14-bit, 5 Msps A/d Converter
• Manufacturer: Intersil Corporation

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 repre-
senting 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
voltage.
The HI5905 can be used with an external reference. The
converter requires only one external reference voltage con-
nected 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 9) 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
common mode voltage range of 1.0V to 4.0V. The perfor-
mance of the ADC does not change significantly with the
value of the analog input common mode voltage.
†
+Full Scale
(+FS) - 1/4
LSB
+FS
LSB
-FS + 1 3/4
LSB
-Full Scale
(-FS) + 3/4
LSB
RIN
+ 3/4 LSB
- 1/4 LSB
The voltages listed above represent the ideal center of each two’s complement binary output code shown.
DESCRIP-
CENTER
CODE
TION
. Internal to the converter, two reference voltages of
-
1 1/4
RIN
AGE
DIFFERENTIAL
+1.99994V
1.99969V
183.105 V
-61.035 V
-1.99957V
-1.99982V
RIN
REFERENCE)
INPUT VOLT-
INTERNAL
pin with V
when using the internal reference
†
(USING
ROUT
20
ROUT
MSB
ROUT
D13
, equal to 4.0V, connected
0
0
0
1
1
1
left open.
and V
D12
1
1
0
1
0
0
RIN
ROUT
RIN
D11
.
1
1
0
1
0
0
TABLE 1. A/D CODE TABLE
must be
D10
1
1
0
1
0
0
TWO’S COMPLEMENT BINARY OUTPUT CODE
HI5905
D9
1
1
0
1
0
0
D8
1
1
0
1
0
0
A 2.3V DC bias voltage source, V
top and bottom internal reference voltages, is made avail-
able 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 ref-
erences is 2V. For the AC coupled differential input, (Figure 9), if
V
phase with V
bias voltage equal to V
on a DC bias voltage equal to V
verter 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
input is at V
(V
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
is seen to have a peak-to-peak differential analog input voltage
range of 2V .
The analog input can be DC coupled (Figure 10) as long as
the inputs are within the analog input common mode voltage
range (1.0V
IN
IN
IN
- is at V
+ - V
is a 2V
D7
1
1
0
1
0
0
FIGURE 9. AC COUPLED DIFFERENTIAL INPUT
IN
-
V
V
- = 2V). Conversely, the ADC will be at negative full
DC
IN
IN
P-P
D6
IN
1
1
0
1
0
0
+1V (V
VDC
, then V
DC
sinewave with -V
+1V and the V
D5
1
1
0
1
0
0
IN
4.0V).
IN
DC
+-V
+ is a 2V
and V
D4
IN
1
1
0
1
0
0
IN
- = -2V). From this, the converter
+ input is equal to V
IN
IN
P-P
D3
DC
- is a 2V
1
1
0
1
0
0
DC
IN
being 180 degrees out of
. Consequently, the con-
sinewave riding on a DC
- input is at VDC-1V
, half way between the
D2
1
1
0
1
0
0
P-P
V
V
V
IN
DC
IN
+
-
sinewave riding
HI5905
D1
1
1
0
1
0
0
DC
LSB
-1V and
D0
1
0
0
1
1
0
IN
+