MAX1228BEEP+ Maxim Integrated Products, MAX1228BEEP+ Datasheet - Page 11
![IC ADC 12BIT 300KSPS 20-QSOP](/photos/6/61/66144/20-qsop_21-0055_sml.jpg)
MAX1228BEEP+
Manufacturer Part Number
MAX1228BEEP+
Description
IC ADC 12BIT 300KSPS 20-QSOP
Manufacturer
Maxim Integrated Products
Datasheet
1.MAX1228BEEP.pdf
(23 pages)
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 3. Equivalent Input Circuit
appropriate bit of the bipolar or unipolar register.
Unipolar mode sets the differential input range from 0 to
V
mode causes the digital output code to be zero.
Selecting bipolar mode sets the differential input range
to ±V
lar mode and two’s complement in bipolar mode. (See
the transfer function graphs, Figures 8 and 9.)
In single-ended mode, the MAX1226/MAX1228/
MAX1230 always operate in unipolar mode. The analog
inputs are internally referenced to GND with a full-scale
input range from 0 to V
The equivalent circuit of Figure 3 shows the
MAX1226/MAX1228/MAX1230s’ input architecture. In
track mode, a positive input capacitor is connected to
AIN0–AIN15 in single-ended mode (and AIN0, AIN2,
AIN4…AIN14 in differential mode). A negative input
capacitor is connected to GND in single-ended mode
(or AIN1, AIN3, AIN5…AIN15 in differential mode). For
external track-and-hold timing, use clock mode 01.
After the T/H enters hold mode, the difference between
the sampled positive and negative input voltages is
converted. The time required for the T/H to acquire an
input signal is determined by how quickly its input
capacitance is charged. If the input signal’s source
impedance is high, the required acquisition time length-
ens. The acquisition time, t
needed for a signal to be acquired, plus the power-up
time. It is calculated by the following equation:
REF
(SINGLE ENDED);
(SINGLE ENDED);
(DIFFERENTIAL)
(DIFFERENTIAL)
. A negative differential analog input in unipolar
AIN4…AIN14
AIN5…AIN15
REF
AIN0-AIN15
AIN0, AIN2,
AIN1, AIN3,
t
AQC
GND
/ 2. The digital output code is binary in unipo-
True Differential Analog Input T/H
=
HOLD
9
x R
______________________________________________________________________________________
(
S
REF
+
GND
REF
V
.
HOLD
CIN+
R
CIN-
DD
IN
ACQ
/2
)
x
, is the maximum time
DAC
24
Temp Sensor, Internal Reference
pF
12-Bit 300ksps ADCs with FIFO,
+
t
PWR
COMPARATOR
HOLD
+
-
where R
input signal, and t
device. The varying power-up times are detailed in the
explanation of the clock mode conversions.
t
ance below 300Ω does not significantly affect the
ADC’s AC performance. A high-impedance source can
be accommodated either by lengthening t
placing a 1µF capacitor between the positive and neg-
ative analog inputs.
The MAX1226/MAX1228/MAX1230 contain a FIFO
buffer that can hold up to 16 ADC results plus one tem-
perature result. This allows the ADC to handle multiple
internally clocked conversions and a temperature mea-
surement, without tying up the serial bus.
If the FIFO is filled and further conversions are request-
ed without reading from the FIFO, the oldest ADC
results are overwritten by the new ADC results. Each
result contains 2 bytes, with the MSB preceded by 4
leading zeros. After each falling edge of CS, the oldest
available byte of data is available at DOUT, MSB first.
When the FIFO is empty, DOUT is zero.
The first 2 bytes of data read out after a temperature mea-
surement always contain the temperature result preceded
by 4 leading zeros, MSB first. If another temperature mea-
surement is performed before the first temperature result
is read out, the old measurement is overwritten by the
new result. Temperature results are in degrees Celsius
(two’s complement) at a resolution of 1/8 of degree. See
the Temperature Measurements section for details on
converting the digital code to a temperature.
The MAX1226/MAX1228/MAX1230 operate from an inter-
nal oscillator, which is accurate within 10% of the 4.4MHz
nominal clock rate. The internal oscillator is active in clock
modes 00, 01, and 10. Read out the data at clock speeds
up to 10MHz. See Figures 4–7 for details on timing speci-
fications and starting a conversion.
The MAX1226/MAX1228/MAX1230 communicate
between the internal registers and the external circuitry
through the SPI-/QSPI-compatible serial interface.
Table 1 details the registers and the bit names. Tables
2–7 show the various functions within the conversion
register, setup register, averaging register, reset regis-
ter, unipolar register, and bipolar register.
ACQ
is never less than 1.4µs, and any source imped-
IN
= 1.5kΩ, R
Applications Information
PWR
S
= 1µs, the power-up time of the
is the source impedance of the
Register Descriptions
Internal Clock
Internal FIFO
ACQ
or by
11