MAX1091BEEI+ Maxim Integrated Products, MAX1091BEEI+ Datasheet - Page 16

• Manufacturer Part Number: MAX1091BEEI+
• Description: IC ADC 10BIT 250KSPS 28-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1091BEEI+

• Number Of Bits: 10
• Sampling Rate (per Second): 250k
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 667mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-QSOP
• Number Of Adc Inputs: 8
• Architecture: SAR
• Conversion Rate: 250 KSPs
• Resolution: 10 bit
• Input Type: Differential
• Interface Type: Parallel
• Voltage Reference: Internal 2.5 V or External
• Supply Voltage (max): 3 V
• Maximum Power Dissipation: 762 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

250ksps, +3V, 8-/4-Channel, 10-Bit ADCs
with +2.5V Reference and Parallel Interface
When applying an external reference to REF, disable
the internal reference buffer by connecting REFADJ to
V
Therefore, an external reference at REF must deliver up
to 200µA DC load current during a conversion and
have an output impedance less than 10Ω. If the refer-
ence has higher output impedance or is noisy, bypass
it close to the REF pin with a 4.7µF capacitor.
Save power by placing the converter in a low-current
shutdown state between conversions. Select standby
mode or shutdown mode using bits D6 and D7 of the
control byte (Tables 1 and 2). In both software power-
down modes, the parallel interface remains active, but
the ADC does not convert.
While in standby mode, the supply current is 850µA
(typ). The part powers up on the next rising edge on
WR and is ready to perform conversions. This quick
turn-on time allows the user to realize significantly
reduced power consumption for conversion rates
below 250ksps.
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-
Figure 8. Unipolar Transfer Function
16
DD
111 . . . 111
111 . . . 110
100 . . . 010
100 . . . 001
100 . . . 000
011 . . . 111
011 . . . 110
011 . . . 101
000 . . . 001
000 . . . 000
. The DC input resistance at REF is 25kΩ.
______________________________________________________________________________________
OUTPUT CODE
(COM)
0
1 LSB =
FS = REF + COM
ZS = COM
1
2
1024
REF
INPUT VOLTAGE (LSB)
Power-Down Modes
512
FULL-SCALE
TRANSITION
Shutdown Mode
Standby Mode
FS -
3
/
2
LSB
FS
ed. A rising edge on WR causes the MAX1091/MAX1093
to exit shutdown mode and return to normal operation.
To achieve full 10-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 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: Bypassing capacitors larger than 4.7µF between
REF and GND results in longer power-up delays.
Table 6 shows the full-scale voltage ranges for unipolar
and bipolar modes.
Figure 8 depicts the nominal, 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
4.8MHz, the specified throughput of 250ksps is
achieved by completing a conversion every 19 clock
cycles: 1 write cycle, 3 acquisition cycles, 13 conver-
Figure 9. Bipolar Transfer Function
*COM ≥ V
011 . . . 111
011 . . . 110
000 . . . 010
000 . . . 001
000 . . . 000
111 . . . 111
111 . . . 110
111 . . . 101
100 . . . 001
100 . . . 000
OUTPUT CODE
REF
/ 2
1 LSB =
- FS
FS = REF
ZS = COM
-FS =
-REF
2
2
1024
REF
+ COM
Maximum Sampling Rate/
+ COM
REF
INPUT VOLTAGE (LSB)
/ 1024.
Achieving 300ksps
COM*
Transfer Function
+FS - 1 LSB