UCC2839
UCC3839
SLUS179A - APRIL 1999 - REVISED NOVEMBER 2001
FEATURES
•Practical Secondary Side Control of
Isolated Power Supplies
•Provides a Self Regulating Bias
Supply From a High Input Voltage
Using an External N-Channel
Depletion Mode FET
•Onboard Precision, Fixed Gain,
Differential Current Sense Amplifier
•Wide Bandwidth Current Error
Amplifier
•5V Reference
•High Current, Programmable Gm
Amplifier Optimized to Drive
Opto-couplers
Secondary Side Average Current Mode Controller
BLOCK DIAGRAM
UDG-97011
DESCRIPTION
The UCC3839 provides the control functions for secondary side average
current mode control in isolated power supplies. Start up, pulse width mod-
ulation and MOSFET drive must be accomplished independently on the
primary side. Communication from secondary to primary side is antici-
pated through an opto-isolator.
Accordingly, the UCC3839 contains a fixed gain current sense amplifier,
voltage and current error amplifiers, and a Gm type buffer/driver amplifier
for the opto-isolator. Additional housekeeping functions include a precision
5V reference and a bias supply regulator.
Power for the UCC3839 can be generated by peak rectifying the voltage of
the secondary winding of the isolation transformer. From this unregulated
voltage, the UCC3839’s bias supply regulator will generate its own 7.5V
bias supply using an external, N-channel, depletion mode FET.
The UCC3839 can be configured for traditional average current mode con-
trol where the output of the voltage error amplifier commands the current
error amplifier. It can also be configured for output voltage regulation with
average current mode short circuit current limiting, employing two parallel
control loops regulating the output voltage and output current independ-
ently.
2
UCC2839
UCC3839
CONNECTION DIAGRAMS
ELECTRICAL CHARACTERISTICS: Unless otherwise specified, 0°C to 70°C for the UCC3839, –40°C to 85° for the
UCC2839. VLINE = 10V, RG = 400Ω. TA=T
J.
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Current Error Amplifier
VIO 10 mV
AVOL 60 dB
CMRR VCM = 0.5V to 5.5V 60 dB
PSRR VLINE = 10V to 20V 60 dB
CAO High CA– = 1V, CA+ = 1.1V, ICAO = –100 A 4.8 7 V
ICAO CA– = 1V, CA+ = 1.1V, CAO = 0.5V –500 –250 µA
CAO Low CA– = 1V, CA+ = 0.9V, ICAO = 500µA 0.2 0.4 V
GBW F = 100kHz, TA= 25°C 3 5 MHz
Voltage Error Amplifier
VA– 1.46 1.5 1.525 V
AVOL 60 dB
PSRR VLINE = 10V to 20V 60 dB
VAO High IVAO = –100µA to 100µA 4.8 5 5.2 V
IVAO VA– = 1.45V, VAO = 0.5V –500 –250 µA
VAO Low VA– = 1.55V, VAO = 0.5V, IVAO = 500µA 0.2 0.4 V
GBW (Note 1) 3 5 MHz
Current Sense Amplifier
CSO Zero CS+ = CS– = –0.3V to 5.5V, ICSO = –100µA to 100µA 0.85 1 1.15 V
AV CS+ = 0, CS– = 0mV to –200mV 7.75 8 8.2 V/V
Current Sense Amplifier (cont.)
Slew Rate CS+ = 0, CS– = 0mV to –0.5V 2 4 V/µs
CSO CS+ = –200mV, CS– = –700mV 4.75 5 5.2 V
LED Driver
ILED LED = 5.5V, CA– = 1V, CA+ = 1.1V, RG = 400 0 10 µA
LED = 5.5V, CA– = 1V, CA+ = 0.9V, RG = 400 9 10 11 mA
Gm LED = 5.5V, CAO = 1V to 3V, RG = 400 2.25 2.5 2.75 mS
Slew Rate CAO = 2V to 2.5V, LED = 400Ωto 5.5V, RG = 400 1 4 V/µs
DIL-14, SOIC-14 (Top View)
D or N Package
ABSOLUTE MAXIMUM RATINGS
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15V
Supply Current
(LED not connected) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2mA
(LED connected) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14mA
Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to 15V
Power Dissipation at TA= 60°C
(LED not connected). . . . . . . . . . . . . . . . . . . . . . . . . . 20mW
(LED connected). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55mW
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature. . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10sec.) . . . . . . . . . . . . . +300°C
Currents are positive into, negative out of the specified terminal.
Consult Packaging Section of Databook for thermal limitations
and considerations of package.
3
UCC2839
UCC3839
ELECTRICAL CHARACTERISTICS: Unless otherwise specified, 0°C to 70°C for the UCC3839, –40°C to 85° for the
UCC2839. VLINE = 10V, RG = 400Ω. TA=T
J.
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Precision Reference
REF TJ= 25°C 4.94 5 5.06 V
IREF = 0mA to 1mA, VLINE = 10V to 20V 4.9 5.1 V
VA+/REF 0.298 0.3 0.302 V/V
VDD Regulator
VDD IDD = 0mA to –15mA, VLINE = 10V to 40V 7 7.5 8 V
IVDD VLINE = 10V to 40V, CA– = 0V, CA+ = 1V, VA– = 2.9V, CS+
= CS– = 0, IREF = 0
1.3 2 mA
Note 1: Ensured by design. Not 100% tested in production.
CA–: Current Error Amplifier Negative Input.
CAO: Current Error Amplifier Output. Output source cur-
rent is limited, and output sink current is guaranteed to
be greater than the VAO output source current. Current
loop compensation components are generally connected
to CAO and CA–.
CA+: Current Error Amplifier Positive Input.
CS–: Current Sense Amplifier Negative Input.
CSO: Current Sense Amplifier Output. Internally set gain
VOUT/VIN = 8 VIN = 0V results in CSO = 1V.
CS+: Current Sense Amplifier Positive Input.
GM: Gm (transconductance) Programming Pin. Resistor
RGM = 400Ωto GND.
GND: Chip Ground.
LED: Output of LED Driver. Connect LED from VDD pin
to LED.
REF: 5V Precision Reference Buffer Output. Minimum
Decoupling Capacitance = 0.01µF
VA–: Voltage Error Amplifier Negative Input. Voltage Er-
ror Amplifier is internally referenced to 1.5V
VAO: Voltage Error Amplifier Output. In a two loop aver-
age current mode control configuration, VAO is con-
nected to CA+ and is the current command signal. VAO
is internally clamped not to exceed 5V for short circuit
control. In a single loop voltage mode control configura-
tion with a parallel average short circuit current control
loop, VAO is connected directly to CAO. Output source
current is limited, and output sink current is guaranteed
to be greater than the CAO output source current.
VDD: 7.5V Regulator output. Supply for most of the chip.
Minimum Decoupling Capacitance = 0.01µF
VGATE: External FET Gate Control Voltage.
PIN DESCRIPTIONS
Fig. 1 shows a typical secondary side average current
mode controller configuration using the UCC3839. In this
configuration, output voltage is sensed and regulated by
the voltage error amplifier. Its output, VAO provides the
reference for the current error amplifier at the CA+ pin.
VAO can be connected to CA+ directly or through a re-
sistive divider depending on the particular application re-
quirements.
Average current mode control needs accurate output cur-
rent information which is provided by a low value current
sense resistor. The voltage proportional to the con-
verter’s output current is sensed and amplified by the
precision current sense amplifier of the chip. The
onboard current sense amplifier has a gain of 8 and is in-
tended for differential sensing of the shunt voltage with a
common mode voltage range from 0V up to 5V. The out-
put of the current sense amplifier, CSO is 1V for zero in-
put which guarantees that the circuit can control currents
down to 0A.
The CSO signal is fed to the CA– input of the current er-
ror amplifier through a resistor. The current error amplifier
takes the VAO and CSO signals and generates the error
signal for the pulse width modulator.
APPLICATION INFORMATION
4
UCC2839
UCC3839
Figure 1. Secondary side average current mode controller.
UDG-97012
Since the PWM function is located on the primary side of
the power converter the CAO signal must be sent across
the safety isolation boundary. The UCC3839 anticipates
an opto-coupler to provide isolation between primary and
secondary. Therefore, CAO drives a transconductance
amplifier that controls LED current in an opto-isolator.
During start up and when CAO exceeds 4V, the current
in the LED drops to zero. Maximum LED current is ob-
tained during normal operation as CAO reaches its low-
est potential. Its value is determined by the programming
resistor value from the GM pin to circuit GND.
An alternative secondary side controller configuration is
introduced in Fig. 2. In this circuit, the voltage and current
control loops of the UCC3839 are connected parallel. It
can be achieved by connecting the VAO and CAO pins
together. The error amplifier with the lower output voltage
controls the current in the opto-coupler providing the
feedback signal for the PWM section on the primary side.
Voltage regulation is still maintained by the voltage error
amplifier until a user programmable output current is
reached. At this time CAO will take control over the Gm
amplifier and the output current of the converter will be
regulated while the output voltage falls below its nominal
value. This current level is set at the CA+ input by a re-
sistive divider from the 5V reference of the chip.
Since the chip is powered from a peak rectifier which
maintains the bias supply for the UCC3839 even under
short circuit conditions, both of these techniques can be
used to eliminate the short circuit runaway problem in
isolated power supplies using peak current mode control
on the primary side.
APPLICATION INFORMATION (cont.)
5
UCC2839
UCC3839
Figure 3. Typical primary side circuit for use with secondary side average current mode controller.
UDG-97014
Figure 2. Voltage mode with average current short circuit limit.
APPLICATION INFORMATION (cont.)
UDG-97014
PACKAGE OPTION ADDENDUM
www.ti.com 7-Jun-2010
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status (1) Package Type Package
Drawing Pins Package Qty Eco Plan (2) Lead/
Ball Finish MSL Peak Temp (3) Samples
(Requires Login)
UCC2839D OBSOLETE SOIC D 14 TBD Call TI Call TI Samples Not Available
UCC2839DG4 OBSOLETE SOIC D 14 TBD Call TI Call TI Samples Not Available
UCC3839D OBSOLETE SOIC D 14 TBD Call TI Call TI Replaced by UC3849DW
UCC3839DG4 OBSOLETE SOIC D 14 TBD Call TI Call TI Samples Not Available
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products Applications
Amplifiers amplifier.ti.com Audio www.ti.com/audio
Data Converters dataconverter.ti.com Automotive www.ti.com/automotive
DLP® Products www.dlp.com Communications and www.ti.com/communications
Telecom
DSP dsp.ti.com Computers and www.ti.com/computers
Peripherals
Clocks and Timers www.ti.com/clocks Consumer Electronics www.ti.com/consumer-apps
Interface interface.ti.com Energy www.ti.com/energy
Logic logic.ti.com Industrial www.ti.com/industrial
Power Mgmt power.ti.com Medical www.ti.com/medical
Microcontrollers microcontroller.ti.com Security www.ti.com/security
RFID www.ti-rfid.com Space, Avionics & www.ti.com/space-avionics-defense
Defense
RF/IF and ZigBee® Solutions www.ti.com/lprf Video and Imaging www.ti.com/video
Wireless www.ti.com/wireless-apps
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2010, Texas Instruments Incorporated
