MAX188ACAP 데이터 시트보기 (PDF) - Maxim Integrated
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MAX188ACAP Datasheet PDF : 24 Pages
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Low-Power, 8-Channel,
Serial 12-Bit ADCs
VDD
DGND
+5V
0.1µF
OSCILLOSCOPE
AGND
0V TO
4.096V
ANALOG 0.01µF
INPUT
MAX186
MAX188
CH7
VSS
CS
SCLK
+5V
D1
1N4148
REFADJ
DIN
DOUT
SSTRB
C2
0.01µF
C1
4.7µF
VREF
SHDN
+2.5V +2.5V **
REFERENCE
+5V
N.C.
2MHz
OSCILLATOR
SCLK
SSTRB
DOUT*
CH1
CH2
CH3
CH4
* FULL-SCALE ANALOG INPUT, CONVERSION RESULT = $FFF (HEX)
**REQUIRED FOR MAX188 ONLY. A POTENTIOMETER MAY BE USED IN PLACE OF THE REFERENCE FOR TEST PURPOSES.
Figure 5. Quick-Look Circuit
Analog Input Range and Input Protection
Internal protection diodes, which clamp the analog
input to VDD and VSS, allow the channel input pins to
swing from VSS - 0.3V to VDD + 0.3V without damage.
However, for accurate conversions near full scale, the
inputs must not exceed VDD by more than 50mV, or be
lower than VSS by 50mV.
If the analog input exceeds 50mV beyond the sup-
plies, do not forward bias the protection diodes of
off-channels over two milliamperes, as excessive
current will degrade the conversion accuracy of the
on-channel.
The full-scale input voltage depends on the voltage at
VREF. See Tables 1a and 1b.
Quick Look
To evaluate the analog performance of the
MAX186/MAX188 quickly, use the circuit of Figure 5.
The MAX186/MAX188 require a control byte to be writ-
ten to DIN before each conversion. Tying DIN to +5V
feeds in control bytes of $FF (HEX), which trigger
Table 1a. Unipolar Full Scale and Zero Scale
Reference
Internal Reference
(MAX186 only)
External Reference
at REFADJ
at VREF
Zero
Scale
0V
Full Scale
+4.096V
0V V REFADJ x A*
0V
VREF
* A = 1.678 for the MAX186, 1.638 for the MAX188
Table 1b. Bipolar Full Scale, Zero Scale, and
Negative Full Scale
Reference
Internal Reference
(MAX186 only)
External Reference
at REFADJ
Negative
Full Scale
-4.096V/2
-1/2VREFADJ
x A*
Zero
Scale
0V
0V
Full Scale
+4.096V/2
+1/2VREFADJ
x A*
at VREF
-1/2 VREF
0V
+1/2 VREF
* A = 1.678 for the MAX186, 1.638 for the MAX188
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