MAX1228BEEP+ Maxim Integrated Products, MAX1228BEEP+ Datasheet - Page 19

• Manufacturer Part Number: MAX1228BEEP+
• Description: IC ADC 12BIT 300KSPS 20-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1228BEEP+

• Number Of Bits: 12
• Sampling Rate (per Second): 300k
• Data Interface: MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 727mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-QSOP
• Number Of Adc Inputs: 12
• Architecture: SAR
• Conversion Rate: 300 KSPs
• Resolution: 12 bit
• Interface Type: Serial
• Voltage Reference: Internal 4.096 V or External
• Supply Voltage (max): 5 V
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 7. Clock Mode 11
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 con-
vert 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 eight 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 tak-
ing CS low again, as long as the 4 leading bits (nor-
mally zeros) are ignored. Internal registers that are
written 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 previously written values. If CS is pulled low
before EOC goes low, a conversion cannot be com-
pleted and the FIFO is corrupted.
DIN
SCLK
DOUT
EOC
CS
EXTERNALLY TIMED ACQUISITION, SAMPLING AND CONVERSION WITHOUT CNVST.
Partial Reads and Partial Writes
______________________________________________________________________________________
(ACQUISITION1)
Temp Sensor, Internal Reference
(CONVERSION BYTE)
12-Bit 300ksps ADCs with FIFO,
MSB1
(CONVERSION1)
Figure 8 shows the unipolar transfer function for single-
ended or differential inputs.
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. Board layout should ensure that digital
and analog signal lines are separated from each other.
Do not run analog and digital (especially clock) signals
parallel to one another or run digital lines underneath the
MAX1226/MAX1228/MAX1230 package. High-frequen-
cy noise in the V
mance. Bypass the V
to GND, close to the V
lengths for best supply-noise rejection. If the power sup-
ply is very noisy, connect a 10Ω resistor in series with
the supply to improve power-supply filtering. For the
QFN package, connect its exposed pad to ground.
Integral nonlinearity (INL) is the deviation of the values
on an actual transfer function from a straight line. This
straight line can be either a best-straight-line fit or a
line drawn between the end points of the transfer func-
tion, once offset and gain errors have been nullified.
INL for the MAX1226/MAX1228/MAX1230 is measured
using the end-point method.
Layout, Grounding, and Bypassing
DD
(ACQUISITION2)
DD
power supply can affect perfor-
DD
LSB1
supply with a 0.1µF capacitor
pin. Minimize capacitor lead
Figure 9
Integral Nonlinearity
Transfer Function
shows the bipolar
Definitions
REF
MSB2
/ 4096V for
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