ACMP
Analog Comparator
XMC™ Microcontrollers
November 2014
ACMP
Analog Comparator
Highlights
XMC1000
ANALOG COMPARATOR
PORTS
INP
INN
+
ORC
-
NVIC
ANTI-GL ITCH
FILTER
ERU
BCCU
OUT
XMC1000 provides up to three Analog
Comparators.
Each analog comparator is realized with
low input offset voltage and short
propagation delay.
The output signal can be routed to a
port pin directly or used by the various
peripherals of the MCU.
Key Feature
Customer Benefits
› Fast and Precise Analog
Comparator
› In power conversion, fast and precise
response improves the control quality.
› The Anti-glitch Filter absorbs undesired
spikes in the compared signal
› Prevent from generation of unintended
edges due to noise in the input signal.
› Anti-glitch Filter
› Programmable Hysteresis
Copyright © Infineon Technologies AG 2015. All rights reserved.
2
ACMP
Fast and Precise Analog Comparator
› Fast and precise:
– The Analog Comparator has a really short response time with
a short propagation delay (25 ns). It has also very low input
offset voltage (3 mV) making it highly accurate.
– Those two features make the ACMP module ideal for Power
Conversion applications, which need real-time and precise
signal level comparisons.
INPUT SIGNALS
Vinn
Vinp
INPUT SIGNALS
Vinp
Vinn
+
ORC
OUTPUT
OUTPUT
0
1
0
1
0
Copyright © Infineon Technologies AG 2015. All rights reserved.
3
ACMP
Anti-glich Filter
› A filter (if enabled) absorbs generated spikes.
– When this filtering operation is added to the ACMP output, the
propagation delay is increased by just a few nanoseconds
(between 2 ns and 10 ns).
ANALOG COMPARATOR
Ref
+
ORC
-
ANTI-GL ITCH
FILTER
(2ns~10ns)
Ref
Copyright © Infineon Technologies AG 2015. All rights reserved.
1
0
1
4
ACMP
Programmable Hysteresis
› A slowly varying signal with even small amounts of noise could
produce unintended comparator output transitions.
› A hysteresis voltage reduces the noise sensibility of the Analog
Comparator.
INPUT
– The configurable values
for the voltage hysteresis are:
Vinn
Vinp
– 10 mV
– 15 mV
– 20 mV
OUTPUT
0
Copyright © Infineon Technologies AG 2015. All rights reserved.
1
0
5
ACMP
System Integration
XMC1100
ERU
ACMP0
+
ORC
ERS &
ETL0
OGU0
XMC1200
XMC1300
●
●
ERS &
ETL1
ACMP1
+
OGU1
Trigger
Cross
Connect
ERS &
ETL2
OGU2
ERS &
ETL3
OGU3
-
ACMP2
+
-
SCU
Comparator Request
BCCU
The output signals of ACMP are
available at the input multiplexer of
the event request unit ERU. As a
result, they can be flexibly combined
to logical signals that trigger
interrupts, start timers or trigger ADC
measurements.
It is the unique combination of fast
analog signals and the powerful
peripherals that provide a solution in
various demanding control
applications.
› Target applications
The fast ACMP is functional in a wide
supply voltage range (-0.05 V~6 V).
– Power Conversion
– Motor Control
– Intelligent Lighting
– General Purpose
Copyright © Infineon Technologies AG 2015. All rights reserved.
6
Application Example
Zero Crossing Detection. Power Factor Correction.
Converter Type: AC-DC / Power Factor Corrector
Topology: Boost Converter
Operation Mode: Critical Conduction Mode (CRM); aka Transition Mode, Boundary Mode or Borderline Mode
Current Control Method: Fixed ON-Time and Zero Crossing Detection
L1
t
D1
+
+
Overview
Q1
Co
Vin(rect)
Vout(dc)
Vin(ac)
-
-
Ext Ref
Voltage
Compensation
Vin
In Power Factor Correction (PFC), Zero
Crossing Detection is widely used as
current control method. There are many
ways of detecting the ZCD instant.
-
+
ACMP
An easy and efficient manner is using one
of the XMC1000 internal fast Analog
Comparator.
XMC12/1300
ERU
CCU
In Brief
This method uses ACMP to detect the ZCD event.
ZCD Detection level needs to be adjusted/tuned to guard against ringing during ZCD. This adjustment can be
done by tuning the reference to the CMP.
Analog Comparator can be used as
Zero Crossing Detector in Power
Factor Correction applications saving
internal (ADC) and external (external
comparators) resources.
Pag e-8.emf
In this example, a PFC using a Boost
Converter topology and implementing
Fixed ON-Time and Zero Crossing
Detection as Current Control
Method(CrCM) is shown. When the
current in the inductor(L1) crosses a fixed
value close to 0, the ACMP reacts
triggering the desired PWM changes in
the CCU through the ERU.
Copyright © Infineon Technologies AG 2015. All rights reserved.
7
Application Example
ZCD in Power Factor Correction
Converter Type: AC-DC / Power Factor Corrector
Topology: Boost Converter
Operation Mode: Critical Conduction Mode (CRM); aka Transition Mode, Boundary Mode or Borderline Mode
Current Control Method: Fixed ON-Time and Zero Crossing Detection
L1
D1
+
+
Q1
Co
Vin(rect)
Vout(dc)
Vin(ac)
-
-
Boost CrCM: Fixed on-Time + ZCD – ACMP Based
Ext Ref
Voltage
Compensation
Vin
-
+
ACMP
Inductor Waveform
XMC12/1300
ERU
CCU
PWM, Fixed On Time
CCU4yST
This method uses ACMP to detect the ZCD event.
ZCD Detection level needs to be adjusted/tuned to guard against ringing during ZCD. This adjustment can be
done by tuning the reference to the CMP.
ACMPx.OUT
Pag e-8.emf
Application Example ZCD in Power Factor Correction
Copyright © Infineon Technologies AG 2015. All rights reserved.
8
ACMP
Additional Features
1
Blanking
2
Common Reference Voltage
Copyright © Infineon Technologies AG 2015. All rights reserved.
9
ACMP
Blanking
› A Blanking feature is added to ensure a stable output when
– enabling the Analog Comparator module
– releasing the Analog Comparator from a low power state
› It adds some blanking time in a range of few microseconds to
prevent from undefined states at the comparator´s output
ANALOG COMPARATOR
+
ORC
-
Microseconds
Blanking
logic
Copyright © Infineon Technologies AG 2015. All rights reserved.
10
ACMP
Common Reference Voltage
XMC1000
› The same reference signal,
divided by two, can be used by
various Analog Comparators
ACMP0
+
ORC
INP0
INN0
REF
-
2
ACMP1
INP1
+
INN1
-
ACMP2
INP2
+
INN2
-
Copyright © Infineon Technologies AG 2015. All rights reserved.
11
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12
Disclaimer
The information given in this training materials is given as a hint for
the implementation of the Infineon Technologies component only and
shall not be regarded as any description or warranty of a certain
functionality, condition or quality of the Infineon Technologies
component.
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