Power Management AAC242/243
© Copyright 2010- ASIC Advantage, Inc. – AADS00012 / R127B - Preliminary - October 2010 1 / 8
AAC242/243 PRELIMINARY DATA
Current Mode PWM Contoller
DESCRIPTION
The AAC242 and AAC243 are part of AAI’s new
family of specialty products for Power Management
applications. The AAC242 and AAC243 are high
performance integrated circuits designed for Off-line
or DC to DC converters using peak current mode
control. The AAC24X has a current sense of 250mV
in comparison to 1V for AAC14X parts.
In offline AC designs the startup is improved by the
low start-up current of the family. The integrated
soft-start function adds to the easy of using the
AAC24X parts in offline applications.
The AAC242 and AAC243 are identical except for the
Under Voltage Lockout. The AAC242 has UVLOon
threshold of 16V and off of 10V making it easy to use
in offline supplies where startup requirements for
energy storage is necessary. For applications using
lower supply voltages the AAC243 has UVLOon of
8.4V and UVLOoff of 7.6V.
The AAC24X family is offered in DIP and SMD
packages. The packages are industry standards and
are ROHS compliant. Extended temperature is
standard with the AAC24X family.
The greater than 1A output driver is ideal for driving
MOSFETs and low power IGBTs. Rise and fall times
are typically less that 30ns with a 1000pF load. The
improvements in switching speed can provide
improvements in efficiency, higher operating
frequency and over current protection.
The AAC24X family has a minimum pulse width of
0.4% allowing operation at very low power without
pulse skipping or erratic operation. The narrower
pulse width capibilities enhances operation at higher
frequencies and voltages.
FEATURES
• Low Start-up current
• Pulse by pulse current limiting
• On board voltage reference
• Under Voltage Lockout with hysteresis
• Simple oscillator circuit
• Over Voltage protection zener
• High current output driver
• Less than 30ns rise and fall times
• Operation to over 1MHz
• Peak Current Mode control
• Integrated Soft-Start Function (~330 Clock
Cycles)
• 100ns leading edge current blanking for reduced
filtering
• 250mV current sense
PIN CONFIGURATION: 8-Lead DIP and SOIC8
View of the AAC24X shown from the top.
V
FB 8
GND4
1
ISENSE
COMP
5
V
REF
Rt/Ct
A
AC242
A
AC243
V
CC
OUT
Power Management AAC242/243
© Copyright 2010- ASIC Advantage, Inc. – AADS00012 / R127B - Preliminary - October 2010 2 / 8
BLOCK DIAGRAM
Open Loop Test Circuit
MAXIMUM RATINGS
PARAMETER PARAMETERS UNITS CONDITIONS
MIN. MAX.
Supply Voltage (Vcc – Ground) 0 30 V Low impedance source
Vfb and Isense Amp Inputs -0.3 5.5 V
Output Current ±1 A
Power Dissipation 1200 mW DIP
1000 mW SOIC8
Operating Junction Temperature 150 °C
Operating Ambient Temperature -40 105 °C
Extended industrial temp. rated
devices
Operating Ambient Temperature -40 125 °C Automotive temp. rated devices
Storage Temperature Range -65 150 °C
Lead Temperature (10 Second) 300 °C Soldering
0.1uF
A
0.1uF
4.7K Ct
Rt
100K
81
2
3
4 5
6
7
VrefCOMP
FB
Isense
R/C GND
OUT
Vcc
1K
OUTPUT
1K/1W
V+
2N3904
4.7K
5K
-
OUTPUT 6
+
+
1 COMP
3 Isense
5.00VREF
8 Vcc
4 Rt/Ct
-
UVLO
34V
5V
REF
2R
S
Vref 7
2 Vf b
2.5V
R
Current Sense
Comparator
REF
OK
DVR
Q
OSC
1V
5 GND
R
Error
Amp
11R
Power Management AAC242/243
© Copyright 2010- ASIC Advantage, Inc. – AADS00012 / R127B - Preliminary - October 2010 3 / 8
ELECTRICAL CHARACTERISTICS
Unless otherwise stated, T=25C, Vcc=15V, RT = 10KΩ, CT = 3300pF.
PARAMETER PARAMETERS UNITS CONDITIONS
MIN. TYP. MAX.
REFERENCE SECTION
Output Voltage 4.95 5.00 5.05 V
Line Regulation 6 15 mV 12V<Vcc<25V
Load Regulation 3 25 mV
Temperature Stability 0.2 mV/°C 0C to 130C
Total Output Variation 4.9 5.1 V Line, Load, and Temperature
Long Term Stability 5 mV Ta=125°C for 1000 hours
Output Short Circuit Current -30 -50 -60 mA
OSCILLATOR SECTION
Frequency Initial Accuracy 47 52 57 KHz Ta=25°C
Frequency Change with Voltage 0.2 1 % 12<Vcc<25V
Frequency Change with Temp. 1 % Tlow<Ta<Thigh
Oscillator Voltage Swing 1.65 Vpp
ERROR AMPLIFIER SECTION
Voltage Feedback Input 2.45 2.5 2.55 V Vout=2.5V
Input Bias Current -1 µA
Open Loop Voltage Gain 90 dB
Unity Gain Bandwidth 10 MHz Tj=25°C
Power Supply Rejection Ratio 70 dB 12V<Vcc<25V
Output Current Sink 12 mA
Output Current Source -1 mA
Output Voltage Swing High 6 V
Output Voltage Swing Low 0.8 V
PULSE WIDTH MODULATION SECTION
Maximum Duty Cycle 97 %
Minimum Duty Cycle 0.4 % Before drop out
CURRENT SENSE SECTION
Voltage Gain 11.4 12.0 12.6 V
Maximum Input Signal 242 250 258 mV
Power Supply Rejection Ratio 70 dB
Input Bias Current -10 µA
Time Delay to Output 300 nS
Power Management AAC242/243
© Copyright 2010- ASIC Advantage, Inc. – AADS00012 / R127B - Preliminary - October 2010 4 / 8
PARAMETER PARAMETERS UNITS CONDITIONS
MIN. TYP. MAX.
OUTPUT SECTION
Voltage Out Low 0.4 V Isink = 20mA
Voltage Out Low 2.2 V Isink = 200mA
Voltage Out High 13.5 14 V Isink = 20mA
Voltage Out High 12.5 13.5 V Isink = 200mA
Voltage Out UVLO 1.1 V Vcc=6V, Isink = 1mA
Voltage Output Rise Time 30 50 ns CL=1000pF
Voltage Output Fall Time 30 50 ns CL=1000pF
Current Output Source Peak 1.2 A
Current Output Sink Peak 0.7 A
UNDER-VOLTAGE LOCKOUT SECTION
Voltage Start Threshold (142) 15 16 17 V
Voltage Start Threshold (143) 7.8 8.4 9 V
Voltage Turnoff Threshold (142) 9 10 11 V
Voltage Turnoff Threshold (143) 7 7.6 8.2 V
Zener Clamp Voltage 30 34 V Icc≤25mA
TOTAL DEVICE SECTION
Start-up Supply Current 0.4 0.6 mA
Operating Supply Current 11 mA
The improved switching performance increases the high peak current associated with internal and external
capacitances and will require careful grounding and PCB trace routing. Bypass and timing capacitors should be of
high quality and located carefully with short traces. The reference capacitor must be located very close to the IC
with minimum trace lengths. A single point ground should be located at pin 5 ground. The use of a good ground
plane is recommended. Under certain conditions of high peak currents it may be advisable to isolate the Vref pin
from the bypass capacitor with a resistor to prevent interaction of the high current with the internal oscillator
operation.
Charge and discharge times are given by the following formulas:
TC=0.55RtCt
TD=RtCtLn[(0.0063Rt-2.7)/(0.0063Rt-4)]
Frequency =( TC+ TD)-1
Oscillator simplified circuit.
Rt
81
2
3
4 5
6
7
VrefCOMP
FB
Isense
R/C GND
OUT
Vcc
Ct
Power Management AAC242/243
© Copyright 2010- ASIC Advantage, Inc. – AADS00012 / R127B - Preliminary - October 2010 5 / 8
Peak current is set by the internal comparator with a fixed limit of 0.250V. Raising the current sense pin (3) to
0.250V or higher will cause a termination of the output pulse regardless of the error amplifier output. The peak
current is normally determined when the current sense pin exceeds the error amplifier conditioned output. Peak
current is determined by the formula:
ISENSE(PK) = 0.250V/RS
In some cases where leading edge switching transients exceed the 100ns blanking, a small RC filter will be required.
Dead/delay time verses Ct
Ct Capacitance in nF
Oscillator Frequency as a function of Rt and Ct
Oscillator frequency in KHz
Rt resistance in KΩ
Delay in µs
RC filter
81
2
3
4 5
6
7
VrefCOMP
FB
Isense
R/C GND
OUT
Vcc
R
C
Rsense
Power Management AAC242/243
© Copyright 2010- ASIC Advantage, Inc. – AADS00012 / R127B - Preliminary - October 2010 6 / 8
In cases where duty cycle exceeds 50% slope compensation is required. This can be implemented by adding a buffer
transistor to the oscillator circuit and using a resistive summing circuit to provide the ramp necessary for slope
compensation.
Shut down circuits depend on the desired function. A transistor can be used to allow control on and off of the PWM
or an SCR can be used to latch off the PWM.
Slope compensation
Ct
81
2
3
4 5
6
7
VrefCOMP
FB
Isense
R/C GND
OUT
Vcc
C
2N3904
Rslope
Rt
Rsense
R
Shutdown circuits
shutdown
81
2
3
4 5
6
7
VrefCOMP
FB
Isense
R/C GND
OUT
Vcc
2N3904
100K
2N3904
shutdown
100K
81
2
3
4 5
6
7
VrefCOMP
FB
Isense
R/C GND
OUT
Vcc
Power Management AAC242/243
© Copyright 2010- ASIC Advantage, Inc. – AADS00012 / R127B - Preliminary - October 2010 7 / 8
OrderingPN(1) Subgroup Description Temp.Range Package PackingTypePackingQty
AAC242E‐D8A‐G‐LF Controller CurrentMode,
OfflineThresholds
Ext.Industrial 8‐PinDIP Tube50
AAC242A‐D8A‐G‐LF Controller CurrentMode,
OfflineThresholds
Automotive 8‐PinDIP Tube50
AAC242E‐S8A‐G‐LF Controller CurrentMode,
OfflineThresholds
Ext.Industrial 8‐PinSOIC Tube98
AAC242E‐S8A‐G‐LF‐TR Controller CurrentMode,
OfflineThresholds
Ext.Industrial 8‐PinSOIC 13”T&R(2) 2500
AAC242A‐S8A‐G‐LF Controller CurrentMode,
OfflineThresholds
Automotive 8‐PinSOIC Tube98
AAC242A‐S8A‐G‐LF‐TR Controller CurrentMode,
OfflineThresholds
Automotive 8‐PinSOIC 13”T&R(2) 2500
AAC242E‐F8A‐G‐LF‐WControllerCurrentMode,
OfflineThresholds
Ext.Industrial3mmx3mm
8‐PinDFN
WafflePackTBD
AC242E‐F8A‐G‐LF‐TRControllerCurrentMode,
OfflineThresholds
Ext.Industrial3mmx3mm
8‐PinDFN
T&R(2)TBD
AAC242A‐F8A‐G‐LF‐WControllerCurrentMode,
OfflineThresholds
Automotive3mmx3mm
8‐PinDFN
WafflePackTBD
AC242A‐F8A‐G‐LF‐TRControllerCurrentMode,
OfflineThresholds
Automotive3mmx3mm
8‐PinDFN
T&R(2)TBD
AAC243E‐D8A‐G‐LF Controller CurrentMode,
BatteryLevelThresholds
Ext.Industrial 8‐PinDIP Tube50
AAC243A‐D8A‐G‐LF Controller CurrentMode,
BatteryLevelThresholds
Automotive 8‐PinDIP Tube50
AAC243E‐S8A‐G‐LF Controller CurrentMode,
BatteryLevelThresholds
Ext.Industrial 8‐PinSOIC Tube98
AAC243E‐S8A‐G‐LF‐TR Controller CurrentMode,
BatteryLevelThresholds
Ext.Industrial 8‐PinSOIC 13”T&R(2) 2500
AAC243A‐S8A‐G‐LF Controller CurrentMode,
BatteryLevelThresholds
Automotive 8‐PinSOIC Tube98
AAC243A‐S8A‐G‐LF‐TR Controller CurrentMode,
BatteryLevelThresholds
Automotive 8‐PinSOIC 13”T&R(2) 2500
AC243E‐F8A‐G‐LF‐WControllerCurrentMode,
BatteryLevelThresholds
Ext.Industrial3mmx3mm
8‐PinDFN
WafflePackTBD
AAC243E‐F8A‐G‐LF‐TRControllerCurrentMode,
BatteryLevelThresholds
Ext.Industrial3mmx3mm
8‐PinDFN
T&R(2)TBD
AC243A‐F8A‐G‐LF‐WControllerCurrentMode,
BatteryLevelThresholds
Automotive3mmx3mm
8‐PinDFN
WafflePackTBD
AAC243A‐F8A‐G‐LF‐TRControllerCurrentMode,
BatteryLevelThresholds
Automotive3mmx3mm
8‐PinDFN
T&R(2)TBD
(1)OnlyRoHS/Lead‐FreePackagingisnormallyoffered.
(2)T&R‐TapeandReel
Ordering Information
Package Dimensions and Marking
The AAC242 and AAC243 are available in a plastic 8-pin DIP or SOIC package. Refer to the latest version of
specification AAPS001 (ASIC Advantage’s “Package Numbering, Marking, and Outline Standard”, available at
www.asicadvantage.com) for specific information concerning the package dimensions and package marking.
Power Management AAC242/243
© Copyright 2010- ASIC Advantage, Inc. – AADS00012 / R127B - Preliminary - October 2010 8 / 8
The following is a brief overview of certain terms and conditions of sale of product. For a full and complete copy of all
the General Terms and Conditions of Sale, visit ou r webpage http://www.asicadvantage.com/terms.htm.
LIMITED WARRANTY
The product is warranted that it will conform to the applicable specifications and be free of defects for one year.
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holds ASIC Advantage, Inc. harmless for claims arising out of the application of ASIC Advantage, Inc.’s products to
Buyer’s designs. Applications described herein or in any catalogs, advertisements or other documents are for
illustrative purposes only.
CRITICAL APPLICATIONS
Products are not authorized for use in critical applications including aerospace and life support applications. Use of
products in these applications is fully at the risk of the Buyer. Critical applications include any system or device
whose failure to perform can result in significant injury to the user.
LETHAL VOLTAGES
Lethal voltages could be present in the applications. Please comply with all applicable safety regulations.
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- AAI’s modified snubber network is patented under the US Patent # 6,233,165
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