MAX1247BCPE+ Maxim Integrated Products, MAX1247BCPE+ Datasheet - Page 19

• Manufacturer Part Number: MAX1247BCPE+
• Description: IC ADC SRL 4CH 12BIT 2.7V 16-DIP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1247BCPE+

• Number Of Bits: 12
• Sampling Rate (per Second): 133k
• Data Interface: MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 842mW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 16-DIP (0.300", 7.62mm)
• Number Of Adc Inputs: 4
• Architecture: SAR
• Conversion Rate: 133 KSPs
• Resolution: 12 bit
• Input Type: Voltage
• Interface Type: 4-Wire (SPI, QSPI, MICROWIRE, TMS320)
• Supply Voltage (max): 5.25 V
• Supply Voltage (min): 2.7 V
• Maximum Power Dissipation: 842 mW
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 13b shows the power consumption with
external-reference compensation in fast power-down,
with one and four channels converted. The external
4.7µF compensation requires a 200µs wait after
power-up with one dummy conversion. This circuit
combines fast multi-channel conversion with the lowest
power consumption possible. Full power-down mode
may provide increased power savings in applications
where the MAX1246/MAX1247 are inactive for long
periods of time, but where intermittent bursts of
high-speed conversions are required.
The MAX1246 can be used with an internal or external
reference voltage, whereas an external reference is
required for the MAX1247. An external reference can
be connected directly at VREF or at the REFADJ pin.
An internal buffer is designed to provide 2.5V at
VREF for both the MAX1246 and the MAX1247. The
MAX1246’s internally trimmed 1.21V reference is buf-
fered with a 2.06 gain. The MAX1247’s REFADJ pin is
also buffered with a 2.00 gain to scale an external 1.25V
reference at REFADJ to 2.5V at VREF.
The MAX1246’s full-scale range with the internal refer-
ence is 2.5V with unipolar inputs and ±1.25V with bipo-
lar inputs. The internal reference voltage is adjustable
to ±1.5% with the circuit in Figure 15.
With both the MAX1246 and MAX1247, an external ref-
erence can be placed at either the input (REFADJ) or
the output (VREF) of the internal reference-buffer ampli-
fier. The REFADJ input impedance is typically 20kΩ for
the MAX1246, and higher than 100kΩ for the MAX1247.
Figure 14. MAX1246 FULLPD/FASTPD Power-Up Sequence
DIN
VREF
REFADJ
1
FULLPD
Internal and External References
1.21V
2.50V
Lowest Power at Higher Throughputs
0V
0V
0 0
______________________________________________________________________________________
Internal Reference (MAX1246)
(ZEROS)
External Reference
COMPLETE CONVERSION SEQUENCE
Serial 12-Bit ADCs in QSOP-16
1
+2.7V, Low-Power, 4-Channel,
τ = RC = 20kΩ x C
FASTPD
9ms WAIT
0 1
REFADJ
Figure 15. MAX1246 Reference-Adjust Circuit
Table 5. Software Power-Down
and Clock Mode
Table 6. Hard-Wired Power-Down
and Internal Clock Frequency
Floating
STATE
t
BUFFEN
SHDN
1
1
0
PD1
0
0
1
1
NOPD
≈ 200µs
CH1
100k
24k
+3.3V
Power-Down
1
DEVICE
Enabled
Enabled
1
MODE
PD0
1
0
1
0
1
FULLPD
510k
CH7
COMPENSATION
0.047µF
REFERENCE
0 0
BUFFER
External
Internal
N/A
(ZEROS)
Fast Power-Down
Full Power-Down
DEVICE MODE
External Clock
Internal Clock
9
REFADJ
1
MAX1246
FASTPD
FREQUENCY
INTERNAL
CLOCK
225kHz
1.8MHz
0 1
N/A
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