Datasheet
Table Of Contents
- FEATURES
- APPLICATIONS
- DESCRIPTION
- ABSOLUTE MAXIMUM RATINGS
- THERMAL INFORMATION
- REGULATORY INFORMATION
- IEC 60747-5-2 INSULATION CHARACTERISTICS
- IEC SAFETY LIMITING VALUES
- IEC 61000-4-5 RATINGS
- IEC 60664-1 RATINGS
- PACKAGE CHARACTERISTICS
- ELECTRICAL CHARACTERISTICS
- PIN CONFIGURATIONS
- TYPICAL CHARACTERISTICS
- THEORY OF OPERATION
- APPLICATION INFORMATION
- ISOLATION GLOSSARY
- REVISION HISTORY
S1
S1
C =3pF
INP
C =3pF
INN
VINN
VINP
VDD1
GND1
GND1
GND1
3pF
R =28kW
IN
3pF
VINN
VINP
Equivalent
Circuit
R =
IN
f C·
CLK DIFF
1
( =10MHz)f
CLK
C =3.6pF
IND
GND1
GND1
400W
400W
S2
S2
AGND+0.8V
AGND+0.8V
AMC1200
AMC1200B
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SBAS542C –APRIL 2011–REVISED SEPTEMBER 2013
THEORY OF OPERATION
INTRODUCTION
The differential analog input of the AMC1200 and AMC1200B is a switched-capacitor circuit based on a second-
order modulator stage that digitizes the input signal into a 1-bit output stream. These devices compare the
differential input signal (V
IN
= VINP – VINN) against the internal reference of 2.5 V using internal capacitors that
are continuously charged and discharged with a typical frequency of 10 MHz. With the S1 switches closed, C
IND
charges to the voltage difference across VINP and VINN. For the discharge phase, both S1 switches open first
and then both S2 switches close. C
IND
discharges to approximately AGND + 0.8V during this phase. Figure 31
shows the simplified equivalent input circuitry.
Figure 31. Equivalent Input Circuit
The analog input range is tailored to directly accommodate a voltage drop across a shunt resistor used for
current sensing. However, there are two restrictions on the analog input signals, VINP and VINN. If the input
voltage exceeds the range AGND – 0.5 V to AVDD + 0.5 V, the input current must be limited to 10 mA to prevent
the implemented input protection diodes from damage. In addition, the linearity and the noise performance of the
device are ensured only when the differential analog input voltage remains within ±250 mV.
The isolated digital bit stream is processed by a third-order analog filter on the low-side and presented as a
differential output of the device.
The SiO
2
-based capacitive isolation barrier supports a high level of magnetic field immunity, as described in
application report SLLA181, ISO72x Digital Isolator Magnetic-Field Immunity (available for download at
www.ti.com).
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