MAX1027 Maxim Integrated Products, MAX1027 Datasheet - Page 19

• Manufacturer Part Number: MAX1027
• Description: MAX1027, MAX1029, MAX1031 10-Bit 300ksps ADCs With Fifo, Temp Sensor, Internal Reference
• Manufacturer: Maxim Integrated Products

clock. Scanning and averaging are disabled, and the
conversion result is available at DOUT during the con-
version. See Figure 7 for clock mode 11 timing.
Initiate a conversion by writing a byte to the conversion
register followed by 16 SCLK cycles. If CS is pulsed
high between the eighth and ninth cycles, the pulse
width must be less than 100µs. To continuously convert
at 16 cycles per conversion, alternate 1 byte of zeros
between each conversion byte.
If reference mode 00 is requested, or if an external ref-
erence is selected but a temperature measurement is
being requested, wait 65µs with CS high after writing
the conversion byte to extend the acquisition and allow
the internal reference to power up. To perform a tem-
perature measurement, write 24 bytes (192 cycles) of
zeros after the conversion byte. The temperature result
appears on DOUT during the last 2 bytes of the 192
cycles.
If the first byte of an entry in the FIFO is partially read
(CS is pulled high after fewer than 8 SCLK cycles), the
second byte of data that is read out contains the next 8
bits (not b7–b0). The remaining bits are lost for that
entry. If the first byte of an entry in the FIFO is read out
fully, but the second byte is read out partially, the rest
of the entry is lost. The remaining data in the FIFO is
uncorrupted and can be read out normally after taking
CS low again, as long as the 4 leading bits (normally
zeros) are ignored. Internal registers that are written
Figure 7. Clock Mode 11
DIN
SCLK
DOUT
EOC
CS
EXTERNALLY TIMED ACQUISITION, SAMPLING AND CONVERSION WITHOUT CNVST.
Partial Reads and Partial Writes
______________________________________________________________________________________
(ACQUISITION1)
Temp Sensor, Internal Reference
10-Bit 300ksps ADCs with FIFO,
(CONVERSION BYTE)
MSB1
(CONVERSION1)
X = DON'T CARE.
partially through the SPI contain new values, starting at
the MSB up to the point that the partial write is stopped.
The part of the register that is not written contains previ-
ously written values. If CS is pulled low before EOC
goes low, a conversion cannot be completed and the
FIFO is corrupted.
Figure 8 shows the unipolar transfer function for single-
ended or differential inputs. Figure 9 shows the bipolar
transfer function for differential inputs. Code transitions
occur halfway between successive-integer LSB values.
Output coding is binary, with 1 LSB = V
unipolar and bipolar operation, and 1 LSB = 0.125°C
for temperature measurements.
For best performance, use PC boards. Do not use wire-
wrap boards. For the QFN package, connect its exposed
pad to GND. Board layout should ensure that digital and
analog signal lines are separated from each other. Do
not run analog and digital (especially clock) signals par-
allel to one another or run digital lines underneath the
MAX1027/MAX1029/MAX1031 package. High-frequency
noise in the V
Bypass the V
close to the V
best supply-noise rejection. If the power supply is very
noisy, connect a 10Ω resistor in series with the supply to
improve power-supply filtering.
Layout, Grounding, and Bypassing
DD
DD
DD
LSB1
pin. Minimize capacitor lead lengths for
supply with a 0.1µF capacitor to GND,
power supply can affect performance.
(ACQUISITION2)
Transfer Function
MSB2
REF
/ 1024V for
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