MAX1295ACEI+ Maxim Integrated Products, MAX1295ACEI+ Datasheet - Page 15

• Manufacturer Part Number: MAX1295ACEI+
• Description: IC ADC 12BIT 265KSPS 28-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1295ACEI+

• Number Of Bits: 12
• Sampling Rate (per Second): 265k
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 762mW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 28-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Table 5. Full-Scale and Zero-Scale for Unipolar and Bipolar Operation
Figure 8. Unipolar Transfer Function
Shutdown mode turns off all chip functions that draw qui-
escent current, reducing the typical supply current to
2µA immediately after the current conversion is complet-
ed. A rising edge on WR causes the MAX1295/MAX1297
to exit shutdown mode and return to normal operation.
To achieve full 12-bit accuracy with a 4.7µF reference
bypass capacitor, 50µs is required after power-up.
Waiting 50µs in standby mode, instead of in full-power
mode, can reduce power consumption by a factor of 3 or
more. When using an external reference, only 50µs is
required after power-up. Enter standby mode by per-
forming a dummy conversion with the control byte speci-
fying standby mode.
Note: Bypass capacitors larger than 4.7µF between
REF and GND result in longer power-up delays.
111 . . . 111
111 . . . 110
100 . . . 010
100 . . . 001
100 . . . 000
011 . . . 111
011 . . . 110
011 . . . 101
000 . . . 001
000 . . . 000
OUTPUT CODE
(COM)
Zero Scale
0
Full Scale
1 LSB =
FS = REF + COM
ZS = COM
1
with +2.5V Reference and Parallel Interface
2
4096
REF
______________________________________________________________________________________
UNIPOLAR MODE
265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
INPUT VOLTAGE (LSB)
2048
FULL-SCALE
TRANSITION
V
Shutdown Mode
REF
FS - 3/2 LSB
COM
+ COM
FS
Table 5 shows the full-scale voltage ranges for unipolar
and bipolar modes. Figure 8 depicts the nominal unipo-
lar 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
4.8MHz, the specified throughput of 265ksps is achieved
by completing a conversion every 18 clock cycles: 1
write cycle, 3 acquisition cycles, 13 conversion 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 300ksps, by first writing a control byte to begin the
Figure 9. Bipolar Transfer Function
*COM ≥ V
011 . . . 111
011 . . . 110
000 . . . 010
000 . . . 001
000 . . . 000
111 . . . 111
111 . . . 110
100 . . . 000
111 . . . 101
100 . . . 001
Negative Full Scale
Positive Full Scale
Zero Scale
OUTPUT CODE
REF
/2
1 LSB =
- FS
FS =
ZS = COM
-FS =
REF
-REF
2
4096
2
REF
BIPOLAR MODE
+ COM
+ COM
Maximum Sampling Rate/
INPUT VOLTAGE (LSB)
COM*
Achieving 300ksps
-V
V
REF
REF
Transfer Function
COM
/2 + COM
/2 + COM
REF
+FS - 1 LSB
/ 4096).
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