MAX1296BEEG Maxim Integrated, MAX1296BEEG Datasheet - Page 15

• Manufacturer Part Number: MAX1296BEEG
• Description: Analog to Digital Converters - ADC
• Manufacturer: Maxim Integrated

Specifications of MAX1296BEEG

• Number Of Channels: 2/1
• Architecture: SAR
• Conversion Rate: 420 KSPs
• Resolution: 12 bit
• Input Type: Single-Ended/Pseudo-Differential
• Snr: Yes
• Interface Type: Parallel
• Operating Supply Voltage: 4.5 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QSOP-24
• Maximum Power Dissipation: 762 mW
• Minimum Operating Temperature: - 40 C
• Number Of Converters: 1
• Voltage Reference: Internal 2.5 V or External

Table 5. Full Scale and Zero Scale for Unipolar and Bipolar Operation
Figure 8. Unipolar Transfer Functions
Shutdown mode turns off all chip functions that draw
quiescent current, reducing the typical supply current
to 2µA immediately after the current conversion is com-
pleted. A rising edge on WR causes the MAX1294/
MAX1296 to exit shutdown mode and return to normal
operation. To achieve full 12-bit accuracy with a 4.7µF
reference bypass capacitor, 500µs is required after
power-up. Waiting 500µs in standby mode, instead of
in full-power mode, can reduce power consumption by
a factor of three or more. When using an external refer-
ence, only 50µs is required after power-up. Enter
standby mode by performing a dummy conversion with
the control byte specifying standby mode.
Note: Bypass capacitors larger than 4.7µF between
REF and GND result in longer power-up delays.
Table 5 shows the full-scale voltage ranges for unipolar
and bipolar modes. Figures 8 depicts the nominal
111 . . . 111
111 . . . 110
100 . . . 010
100 . . . 001
100 . . . 000
011 . . . 111
011 . . . 110
011 . . . 101
000 . . . 001
000 . . . 000
OUTPUT CODE
(COM)
with +2.5V Reference and Parallel Interface
Zero Scale
Full Scale
0
1 LSB =
FS = REF + COM
ZS = COM
—
1
2
4096
REF
______________________________________________________________________________________
420ksps, +5V, 6-/2-Channel, 12-Bit ADCs
UNIPOLAR MODE
INPUT VOLTAGE (LSB)
2048
FULL-SCALE
TRANSITION
Transfer Function
V
Shutdown Mode
REF
COM
FS - 3/2 LSB
—
+ COM
FS
unipolar input/output (I/O) transfer function, and Figure 9
shows the bipolar I/O transfer function. Code transitions
occur halfway between successive-integer LSB values.
Output coding is binary, with 1 LSB = (V
When running at the maximum clock frequency of
7.6MHz, the specified throughput of 420ksps is
achieved by completing a conversion every 18 clock
cycles: 1 write cycle, 3 acquisition cycles, 13 conver-
sion cycles, and 1 read cycle. This assumes that the
results of the last conversion are read before the next
control byte is written. It is possible to achieve higher
throughputs, up to 475ksps, by first writing a control
byte to begin the acquisition cycle of the next conver-
sion, and then reading the results of the previous con-
version from the bus. This technique (Figure 10) allows
a conversion to be completed every 16 clock cycles.
Note that the switching of the data bus during acquisi-
Figure 9. Bipolar Transfer Functions
*COM ≥ V
011 . . . 111
011 . . . 110
000 . . . 010
000 . . . 001
000 . . . 000
111 . . . 111
111 . . . 110
111 . . . 101
100 . . . 001
100 . . . 000
Negative Full Scale
Positive Full Scale
Zero Scale
OUTPUT CODE
REF
/ 2
- FS
1 LSB =
FS = REF
ZS = COM
-FS =
-REF
2
2
BIPOLAR MODE
4096
REF
+ COM
+ COM
Maximum Sampling Rate/
INPUT VOLTAGE (LSB)
COM*
Achieving 475ksps
-V
V
REF
REF
COM
/2 + COM
/2 + COM
REF
+FS - 1 LSB
/ 4096).
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