UC19431
UC29431
UC39431
UC39431B
DESCRIPTION
The UC39431 is an adjustable shunt voltage regulator with 100mA sink ca-
pability. The architecture, comprised of an error amplifier and
transconductance amplifier, gives the user separate control of the small
signal error voltage frequency response along with a fixed linear
transconductance. A minimum 3MHz gain bandwidth product for both the
error and transconductance amplifiers assures fast response. In addition to
external programming, the IC has three internal resistors that can be con-
nected in six different configurations to provide regulated voltages of 2.82V,
3.12V, 5.1V, 7.8V, 10.42V, and 12.24V. A sister device (UC39432) provides
access to the non-inverting error ampilifer input and reference, while elimi-
nating the three internal resistors.
Precision Adjustable Shunt Regulator
FEATURES
•Multiple On-Chip Programmable
Reference Voltages
•0.4% Initial Accuracy
•0.7% Overall Reference Tolerance
•2.2V to 36.0V Operating Supply
Voltage and User Programmable
Reference
•36.0V Operating Supply Voltage
•Reference Accuracy Maintained For
Entire Range of Supply Voltage
•Superior Accuracy and Easier
Compensation for Optoisolator
Application
•Improved Architecture Provides a
Known Linear Transconductance with
a +5% Typical Tolerance
04/99
BLOCK DIAGRAM
UDG-95087
2
UC19431
UC29431
UC39431
UC39431B
DIL-8, SOIC-8 (Top View)
N or J, D Package
ABSOLUTE MAXIMUM RATINGS
Supply Voltage: V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36V
Regulated Output: V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36V
Internal Resistors: R1, R2, R3. . . . . . . . . . . . . . . . . . . . . . . 13V
E/A Input: SENSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V
E/A Compensation: COMP . . . . . . . . . . . . . . . . . . . . . . . . . . 6V
Output Sink Current: I. . . . . . . . . . . . . . . . . . . . . . . . . . . 140mA
Power Dissipation at TA≤25°C (DIL-8). . . . . . . . . . . . . . . . . 1W
Derate 8mW/°C for TA> 25°C
Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature. . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 sec.). . . . . . . . . . . . . +300°C
Currents are positive into, negative out of the specified termi-
nal. Consult Packaging Section of Databook for thermal limita-
tions and considerations of packages.
ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications apply for TA= –55°C to +125°C and
COLL Output = 2.4V to 36.0V for the UC19431, TA= –25°C to +85°C and COLL Output = 2.3V to 36.0V for the UC29431, and TA
= 0°C to +70°C and COLL Output = 2.3V to 36.0V for the UC39431/B, VCC = 15V, ICOLL = 10mA, TA=T
J.
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Reference Voltage Tolerance TA= 25°C 19431* 1.295 1.3 1.305 V
39431B 1.29 1.3 1.31 V
Reference Temperature Tolerance VCOLL = 5.0 19431* 1.291 1.3 1.309 V
39431B 1.286 1.3 1.314 V
Reference Line Regulation
Reference Load Regulation
VCC = 2.2V to 36.0V, VCOLL = 5V
ICOLL = 10mA to 50mA, VCOLL = 5V
19431* 10 38 mV
39431B
19431* 10
10 57
38 mV
mV
39431B 10 57 mV
Sense Input Current –0.5 –0.2 µA
Minimum Operating Current VCC = 36.0V, VCOLL = 5V 0.50 0.80 mA
Collector Current Limit VCOLL = VCC = 36.0V, Ref = 1.35V 130 145 mA
Collector Saturation ICOLL = 20mA 0.7 1.1 1.5 V
Transconductance (gm) VCC = 2.4V to 36.0V,
VCOLL = 3V, ICOLL = 20mA 19431* –170 –140 –110 mS
39431B –180 –140 –100 mS
5.1V Reference Internal Divider 19431* 5.05 5.1 5.15 V
39431B 5 5.1 5.2 V
12.24V Reference Internal Divider 19431* 12 12.24 12.5 V
39431B 12 12.24 12.5 V
Error Amplifier AVOL 60 90 dB
Error Amplifier GBW (Note 1) 3.0 5 MHz
Transconductance Amplifier GBW 3 MHz
* Also applies to the UC29431 and UC39431
Note: The internal divider can be configured to give six unique references. These references are 2.82V, 3.12V, 5.1V, 7.8V,
10.42V, 12.24V.
Note 1: Guaranteed by design. Not 100% tested in production.
CONNECTION DIAGRAM
3
UC19431
UC29431
UC39431
UC39431B
COLL: The collector of the output transistor with a maxi-
mum voltage of 36V. This pin is the output of the
transconductance amplifier. The overall open loop volt-
age gain of the transconductance amplifier is gm • RL,
where gm is designed to be –140mS ±30mS and RL rep-
resents the output load.
COMP: The output of the error amplifier and the input to
the transconductance amplifier. This pin is available to
compensate the high frequency gain of the error ampli-
fier. It is internally voltage limited to approximately 2.0V.
GND: The reference and power ground for the device.
The power ground of the output transistor is isolated on
the chip from the substrate ground used to bias the re-
mainder of the device.
R1, R2, R3: Connection points to the three internal resis-
tors.
SENSE: The inverting terminal of the error amplifier used
as both the voltage sense input to the error amplifier and
its other compensation point. The error amplifier uses the
SENSE input to compare against the 1.3V on-chip refer-
ence.
The SENSE pin is also used as the undervoltage lockout
(UVLO). It is intended to keep the chip from operating un-
til the internal reference is properly biased. The thresh-
old is approximately 1V. It is important that once the
UVLO is released, the error amplifier can drive the
transconductance amplifier to stabilize the loop. If a ca-
pacitor is connected between the SENSE and COMP
pins to create a pole, it will limit the slew rate of the error
amplifier. To increase the bandwidth and ensure startup
at low load current, it is recommended to create a zero
along with the pole as shown in the shunt regulator appli-
cation. The error amplifier must slew 2.0V to drive the
transconductance amplifier initially on.
VCC: The power connection for the device.The minimum
to maximum operating voltage is 2.2V to 36.0V. The qui-
escent current is typically 0.50mA.
PIN DESCRIPTIONS (cont.)
Figure 1. Typical 5.1V shunt regulator application.
UDG-95088
4
UC19431
UC29431
UC39431
UC39431B
Magnetic Amplifier Controller Application
The 0.4% initial reference makes the UC39431 ideal as a
programmable shunt regulator. By adding two external
resistors, the on-chip 1.3V reference can be gained to
any voltage between 2.2V (2.4V for the UC39431) and
36.0V. The input bias current is typically maintained at
0.2µA for the output voltage range. Since the
non-inverting error amplifier input is not available, a 5.1k
non-inverting input impedance is added to the input of
the error amplifier. This allows the user to choose the
SENSE pin input impedance to cancel the minimal offset
voltage caused by the input bias current.
Frequency Compensation
The UC39431 shunt regulator is designed with two
independant gain stages. The error amplifier provides
90dB of gain with a typical gain bandwidth product of
5MHz. The error amplifier provides sufficient gain in or-
der for the sense voltage to be accurately compared to
the 1.3V on-chip reference. Complete control of the fre-
quency response of the error amplifier is accomplished
with the COMP pin. By putting negative feedback across
the error amplifier, either a pole or a pole-zero can be
added.
The second gain stage is the transconductance (gm) am-
plifier. The gm amplifier is designed with a known linear
140mS of transconductance. The voltage gain is conse-
quently gm • Ro, where Ro is the output impedance at
the collector pin. The frequency response of the
transconductance amplifier is controlled with the COLL
pin. The gain bandwidth product of the gm amplifier is
typically 3MHz. A pole or pole-zero can be added to this
stage by connecting a capacitor or a series capacitor and
resistor between COLL and GND.
The compensation of a control loop containing the
UC39431 is made easier due to the independant com-
pensation capability of the error amplifier and gm ampli-
fier. As shown in the applications information, a pole-zero
is created with a series resistor and capacitor between
SENSE and COMP. The pole created is dominant, while
the zero is used to increase the bandwidth and cancel
the effects of the pole created by the capacitor between
the COLL and GND pins.
APPLICATION INFORMATION
6
5
7
4
20k
4k
REF
2.85k
2
22.4k
16k
5.1Ω
8
1
3
1.3V 0.5V
GND
COLL
ICOLL
40.2K 6.8nF
21K
VSENSE
R1
R2
R3
SENSE
2K
COMP VCC
Figure 2. 15.0V optocoupler application.
UDG-99051
5
UC19431
UC29431
UC39431
UC39431B
Optocoupler Application
The two amplifier circuit architecture employed in the
UC39431 is most advantageous for the optocoupler ap-
plication. The error amplifier provides a fixed open loop
gain that is available to apply flexible loop compensation
of either poles or zeroes. A fixed transconductance am-
plifier provides a linear current source compared to the
typical transistor’s exponential output characteristics. It
also eliminates the traditional optocoupler’s CTR varia-
tions with power supply and voltage, and the need to
suffer the additional voltage drop of a series resistor.
Magnetic Amplifier Controller Application
The UC39431 makes an excellent controller for magnetic
amplifier regulated outputs. Working from either a square
wave drive or from a PWM signal controlled by another
output, a saturable reactor provides highly efficient con-
trol, requiring only a reset current which can be gener-
ated from its own output.
APPLICATION INFORMATION (cont.)
Figure 3. Magnetic amplifier controller application.
UDG-95090
6
UC19431
UC29431
UC39431
UC39431B
Figure 4. Internal 1.3V vs. temperature. Figure 5. Error amp voltage gain and phase vs.
frequency.
UNITRODE CORPORATION
7 CONTINENTAL BLVD. • MERRIMACK, NH 03054
TEL. (603) 424-2410 • FAX (603) 424-3460
UDG-95092UDG-95091
Table 1. Resistor divider connection table for shunt applications
REGULATED VOLTAGE CONNECT R1 TO: CONNECT R2 TO: CONNECT R3 TO:
2.82V SENSE (pin 7) COLL (pin 1) SENSE (pin 7)
3.12V open COLL (pin 1) SENSE (pin 7)
5.1V COLL (pin 1) SENSE (pin 7) open
7.8V COLL (pin 1) SENSE (pin 7) GND (pin 8)
10.42V COLL (pin 1) SENSE (pin 7) SENSE (pin 7)
12.24V COLL (pin 1) open SENSE (pin 7)
Note: To obtain the shunt regulated or optocoupler sensed voltage specified in the left column, connect the internal resistors (R1,
R2, R3) as indicated. Refer to the shunt regulator application in Fig.1.
PACKAGING INFORMATION
Orderable Device Status (1) Package
Type Package
Drawing Pins Package
Qty Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
UC19431J OBSOLETE CDIP JG 8 TBD Call TI Call TI
UC19431J883B OBSOLETE CDIP JG 8 TBD Call TI Call TI
UC29431D ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
UC29431DG4 ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
UC39431D ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
UC39431DG4 ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
UC39431N ACTIVE PDIP P 8 50 Green (RoHS &
no Sb/Br) CU NIPDAU N / A for Pkg Type
UC39431NG4 ACTIVE PDIP P 8 50 Green (RoHS &
no Sb/Br) CU NIPDAU N / A for Pkg Type
(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.
PACKAGE OPTION ADDENDUM
www.ti.com 18-Sep-2008
Addendum-Page 1
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 shouldobtain the latest relevant information before placing orders and should verify that such information is current and complete. All products aresold 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 standardwarranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except wheremandated 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 andapplications using TI components. To minimize the risks associated with customer products and applications, customers should provideadequate 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. Informationpublished by TI regarding third-party products or services does not constitute a license from TI to use such products or services or awarranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectualproperty 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 accompaniedby all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptivebusiness practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additionalrestrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids allexpress and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is notresponsible 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 reasonablybe expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governingsuch use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, andacknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their productsand any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may beprovided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products insuch safety-critical applications.TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products arespecifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet militaryspecifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely atthe 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 aredesignated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designatedproducts 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 ApplicationsAmplifiers amplifier.ti.com Audio www.ti.com/audioData Converters dataconverter.ti.com Automotive www.ti.com/automotiveDSP dsp.ti.com Broadband www.ti.com/broadbandClocks and Timers www.ti.com/clocks Digital Control www.ti.com/digitalcontrolInterface interface.ti.com Medical www.ti.com/medicalLogic logic.ti.com Military www.ti.com/militaryPower Mgmt power.ti.com Optical Networking www.ti.com/opticalnetworkMicrocontrollers microcontroller.ti.com Security www.ti.com/securityRFID www.ti-rfid.com Telephony www.ti.com/telephonyRF/IF and ZigBee® Solutions www.ti.com/lprf Video & Imaging www.ti.com/videoWireless www.ti.com/wireless
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265Copyright © 2008, Texas Instruments Incorporated
