MAX148BMJP Maxim Integrated, MAX148BMJP Datasheet - Page 18

• Manufacturer Part Number: MAX148BMJP
• Description: Analog to Digital Converters - ADC
• Manufacturer: Maxim Integrated

Specifications of MAX148BMJP

• Number Of Channels: 8/4
• Architecture: SAR
• Conversion Rate: 133 KSPs
• Resolution: 10 bit
• Input Type: Single-Ended/Differential
• Snr: Yes
• Interface Type: 4-Wire, Microwire, QSPI, Serial, SPI
• Operating Supply Voltage: 2.7 V to 5.25 V
• Maximum Operating Temperature: + 125 C
• Package / Case: CDIP N
• Maximum Power Dissipation: 640 mW
• Minimum Operating Temperature: - 55 C
• Number Of Converters: 1
• Voltage Reference: External

+2.7V to +5.25V, Low-Power, 8-Channel,
Serial 10-Bit ADCs
Figure 14b shows the power consumption with external-
reference compensation in fast power-down, with one
and eight channels converted. The external 4.7FF com-
pensation requires a 75Fs wait after power-up with one
dummy conversion. This graph shows fast multichannel
conversion with the lowest power consumption possible.
Full power-down mode may provide increased power
savings in applications where the MAX148/MAX149 are
inactive for long periods of time, but where intermittent
bursts of high-speed conversions are required.
The MAX149 can be used with an internal or external
reference voltage, whereas an external reference is
required for the MAX148. An external reference can be
connected directly at V
An internal buffer is designed to provide 2.5V at V
for both the MAX149 and the MAX148. The MAX149’s
internally trimmed 1.21V reference is buffered with a
2.06 gain. The MAX148’s REFADJ pin is also buffered
with a 2.00 gain to scale an external 1.25V reference at
REFADJ to 2.5V at V
Figure 15. MAX149 FULLPD/FASTPD Power-Up Sequence
Figure 16. MAX149 Reference-Adjust Circuit
18
REFADJ
V
DIN
REF
100kI
24kI
Internal and External References
1
+3.3V
FULLPD
Lowest Power at Higher Throughputs
1.21V
2.50V
REF
0 0
510kI
0
0
0.01µF
REF
.
or at the REFADJ pin.
12
REFADJ
MAX149
(ZEROS)
H = RC = 20kI x C
COMPLETE CONVERSION SEQUENCE
1
FASTPD
REFADJ
REF
1.6ms WAIT
0 1
Figure 17. Unipolar Transfer Function, Full Scale (V
+ V
The MAX149’s full-scale range with the internal refer-
ence is 2.5V with unipolar inputs and Q1.25V with bipolar
inputs. The internal reference voltage is adjustable to
Q1.5% with the circuit in Figure 16.
With both the MAX149 and MAX148, an external refer-
ence can be placed at either the input (REFADJ) or the
output (V
The REFADJ input impedance is typically 20kI for the
MAX149, and higher than 100kI for the MAX148. At
V
During conversion, an external reference at V
REF
COM
t
BUFFEN =
1
11...111
11...110
11...101
00...011
00...010
00...001
00...000
, the DC input resistance is a minimum of 18kI.
OUTPUT CODE
, Zero Scale (ZS) = COM
CH1
NOPD
(COM)
75Fs
REF
0
1
) of the internal reference-buffer amplifier.
1
1
2
INPUT VOLTAGE (LSB)
1
3
TRANSITION
FULLPD
CH7
Internal Reference (MAX149)
0 0
FULL-SCALE
TRANSITION
(ZEROS)
External Reference
FS - 3/2 LSB
1
FASTPD
1 LSB =
ZS = COM
V
FS
= V
FS
0 1
REF
FS
1024
V
REF
REF
+ V
) = V
COM
must
REF