UC1825_DataSheet

UC1825UC2825UC3825

•Compatible with Voltage or Current Mode Topologies

•Practical Operation Switching Frequencies

to 1MHz

•50ns Propagation Delay to Output •High Current Dual Totem Pole Outputs (1.5A Peak)•Wide Bandwidth Error Amplifier

•Fully Latched Logic with Double Pulse Suppression •Pulse-by-Pulse Current Limiting

•Soft Start / Max. Duty Cycle Control

•Under-Voltage Lockout with Hysteresis

•

Low Start Up Current (1.1mA)

The UC1825family of PWM control ICs is optimized for high fre-quency switched mode power supply applications.Particular care was given to minimizing propagation delays through the comparators

and logic circuitry while maximizing bandwidth and slew rate of the error amplifier.This controller is designed for use in either cur-rent-mode or voltage mode systems with the capability for input volt-age feed-forward.Protection circuitry includes a current limit comparator with a 1V

threshold,a TTL compatible shutdown port,and a soft start pin

which will double as a maximum duty cycle clamp.The logic is fully

latched to provide jitter free operation and prohibit multiple pulses at an output.An under-voltage lockout section with 800mV of hysteresis

assures low start up current.During under-voltage lockout,the out-puts are high impedance.

These devices feature totem pole outputs designed to source and sink high peak currents from capacitive loads,such as the gate of a power MOSFET.The on state is designed as a high level.

High Speed PWM Controller

FEATURES

DESCRIPTION

ABSOLUTE MAXIMUM RATINGS(Note 1)

Supply Voltage (Pins 13, 15). . . . . . . . . . . . . . . . . . . . . . . .30V

Output Current, Source or Sink (Pins 11, 14)

DC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.5A

Pulse (0.5s). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.0A

Analog Inputs

(Pins 1, 2, 7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.3V to 7V

(Pin 8, 9). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.3V to 6V

Clock Output Current (Pin 4). . . . . . . . . . . . . . . . . . . . . . .-5mA

Error Amplifier Output Current (Pin 3). . . . . . . . . . . . . . . .5mA

Soft Start Sink Current (Pin 8). . . . . . . . . . . . . . . . . . . . .20mA

Oscillator Charging Current (Pin 5). . . . . . . . . . . . . . . . . .-5mA

Power Dissipation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1W

Storage Temperature Range. . . . . . . . . . . . . .-65°C to +150°C

Lead Temperature (Soldering, 10 seconds). . . . . . . . . .300°C

Package Q JA Q JC

DIL-16J80-12028(2)

DIL-16N90(1)45

PLCC-2043-75(1)34

LCC-2070-8020(2)

SOIC-1650-120(1)35 THERMAL RATINGS TABLE

Q

QELECTRICAL CHARACTERISTICS:Unless otherwise stated, these specifications apply for , R T= 3.65k, C T= 1nF,V CC = 15V, -55°CUC1825

UC3825 PARAMETERS TEST CONDITIONS UC2825

MIN TOP MAX MIN TOP MAX UNITS Reference Section

Output Voltage T O= 25°C, I O= 1mA 5.05 5.10 5.15 5.00 5.10 5.20V Line Regulation10V Initial Accuracy*T J= 2°C360400440360400440kHz Voltage Stability*10V Clock Out High 3.9 4.5 3.9 4.5V Clock Out Low 2.3 2.9 2.3 2.9V Ramp Peak* 2.6 2.8 3.0 2.6 2.8 3.0V Ramp Valley*0.7 1.0 1.250.7 1.0 1.25V Ramp Valley to Peak* 1.6 1.8 2.0 1.6 1.8 2.0V Error Amplifier Section

Input Offset Voltage1015mV Input Bias Current0.630.63µA Input Offset Current0.110.11µA Open Loop Gain1V < V O< 4V60956095dB CMRR 1.5V UC1825UC3825PARAMETERS TEST CONDITIONS

UC2825MIN TOP MAX

MIN

TOP MAX UNITS PWM Comparator Section Pin 7 Bias Current V PIN 7= 0V -1

-5-1

-5µA Duty Cycle Range

080

085%Pin 3 Zero DC Threshold V PIN 7= 0V 1.1

1.25 1.1

1.25V Delay to Output *50805080ns Soft-Start Section Charge Current V PIN 8= 0.5V 3

9

20

39

20

µA Discharge Current V PIN 8= 1V 1

1

mA Current Limit / Shutdown Section Pin 9 Bias Current 0 1.40 1.55 1.25

1.40 1.55V Delay to Output 50805080ns Output Section Output Low Level I OUT = 20mA

0.250.400.250.40V I OUT = 200mA

1.2

2.2

1.2

2.2

V Output High Level I OUT = -20mA

13.013.513.013.5V I OUT = -200mA

12.013.012.0

13.0V Collector Leakage V C = 30V 10050010500µA Rise/Fall Time *CL = 1nF 30603060ns Under-Voltage Lockout Section Start Threshold 8..29.68..29.6V UVLO Hysteresis

0.4

0.8 1.20.4

0.8 1.2V Supply Current Section Start Up Current V CC = 8V 1.1 2.5 1.1 2.5mA ICC V PIN 1, V PIN 7, V PIN 9= 0V; V PIN 2= 1V

22

33

22

33

mA

ELECTRICAL CHARACTERISTICS:Unless otherwise stated, these specifications apply for , R T = 3.65k, C T = 1nF,V CC

= 15V, -55°CHigh speed circuits demand careful attention to layout and component placement.To assure proper perfor-mance of the UC1825follow these rules:1)Use a ground plane.2)Damp or clamp parasitic inductive kick energy from the gate of driven MOSFETs.Do not allow the out-put pins to ring below ground.A series gate resistor or a shunt1Amp Schottky diode at the output pin will serve this purpose.3)Bypass V CC,V C,and V REF.Use0.1µF monolithic ceramic capacitors with low equivalent series inductance.Allow less than1cm of total lead length for each capacitor between the bypassed pin and the ground plane.4)Treat the timing capacitor,CT,like a bypass ca-pacitor.

Printed Circuit Board Layout ConsiderationsUC1825

UC2825 Oscillator Circuit

UC3825

UC1825

UC2825 Forward Technique for Off-Line Voltage Mode Application

UC3825

Constant Volt-Second Clamp Circuit

Output Section

UC1825

UC2825 Open Loop Laboratory Test Fixture

UC3825

Design Example: 50W, 48V to 5V DC to DC Converter - 1.5MHz Clock Frequency

PACKAGING INFORMATION

Orderable Device Status(1)Package

Type Package

Drawing

Pins Package

Qty

Eco Plan(2)Lead/Ball Finish MSL Peak Temp(3)

5962-87681012A ACTIVE LCCC FK201TBD POST-PLATE Level-NC-NC-NC 5962-8768101EA ACTIVE CDIP J161TBD A42SNPB Level-NC-NC-NC 5962-8768101QFA ACTIVE CFP W161TBD A42SNPB Level-NC-NC-NC 5962-8768101V2A ACTIVE LCCC FK201TBD Call TI Level-NC-NC-NC 5962-8768101VEA ACTIVE CDIP J161TBD Call TI Level-NC-NC-NC UC1825J ACTIVE CDIP J161TBD A42SNPB Level-NC-NC-NC

UC1825J883B ACTIVE CDIP J161TBD A42SNPB Level-NC-NC-NC

UC1825JQMLV ACTIVE CDIP J16TBD Call TI Call TI UC1825L ACTIVE LCCC FK201TBD POST-PLATE Level-NC-NC-NC

UC1825L883B ACTIVE LCCC FK201TBD POST-PLATE Level-NC-NC-NC

UC1825LQMLV ACTIVE LCCC FK20TBD Call TI Call TI

UC1825W883B ACTIVE CFP W161TBD A42SNPB Level-NC-NC-NC UC2825DW ACTIVE SOIC DW10Green(RoHS&

no Sb/Br)

CU NIPDAU Level-2-260C-1YEAR

UC2825DW/1PREVIEW SOIC DW16Green(RoHS&

no Sb/Br)

CU NIPDAU Level-2-260C-1YEAR

UC2825DWTR ACTIVE SOIC DW162000Green(RoHS&

no Sb/Br)

CU NIPDAU Level-2-260C-1YEAR

UC2825DWTRG4ACTIVE SOIC DW162000Green(RoHS&

no Sb/Br)

CU NIPDAU Level-2-260C-1YEAR UC2825J ACTIVE CDIP J161TBD A42SNPB Level-NC-NC-NC UC2825N ACTIVE PDIP N1625Green(RoHS&

no Sb/Br)

CU NIPDAU Level-NC-NC-NC

UC2825NG4ACTIVE PDIP N1625Green(RoHS&

no Sb/Br)

CU NIPDAU Level-NA-NA-NA

UC2825Q ACTIVE PLCC FN2046Green(RoHS&

no Sb/Br)

CU SN Level-2-260C-1YEAR

UC2825QTR ACTIVE PLCC FN201000Green(RoHS&

no Sb/Br)

CU SN Level-2-260C-1YEAR

UC3825DW ACTIVE SOIC DW10Green(RoHS&

no Sb/Br)

CU NIPDAU Level-2-260C-1YEAR

UC3825DWG4ACTIVE SOIC DW10Green(RoHS&

no Sb/Br)

CU NIPDAU Level-2-260C-1YEAR

UC3825DWTR ACTIVE SOIC DW162000Green(RoHS&

no Sb/Br)

CU NIPDAU Level-2-260C-1YEAR

UC3825DWTRG4ACTIVE SOIC DW162000Green(RoHS&

no Sb/Br)

CU NIPDAU Level-2-260C-1YEAR UC3825J ACTIVE CDIP J161TBD A42SNPB Level-NC-NC-NC UC3825N ACTIVE PDIP N1625Green(RoHS&

no Sb/Br)

CU NIPDAU Level-NC-NC-NC

UC3825NG4ACTIVE PDIP N1625Green(RoHS&

no Sb/Br)

CU NIPDAU Level-NC-NC-NC

UC3825Q ACTIVE PLCC FN2046Green(RoHS&

no Sb/Br)

CU SN Level-2-260C-1YEAR

UC3825QTR ACTIVE PLCC FN201000Green(RoHS&

no Sb/Br)

CU SN Level-2-260C-1YEAR

(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)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 all6substances,including the requirement that lead not exceed0.1%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.

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 exceed0.1%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.

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. T esting 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. T o 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 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.

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. 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

DSP dsp.ti.com Broadband www.ti.com/broadband

Interface interface.ti.com Digital Control www.ti.com/digitalcontrol

Logic logic.ti.com Military www.ti.com/military

Power Mgmt power.ti.com Optical Networking www.ti.com/opticalnetwork Microcontrollers microcontroller.ti.com Security www.ti.com/security

Telephony www.ti.com/telephony

Video & Imaging www.ti.com/video

Wireless www.ti.com/wireless

Mailing Address:Texas Instruments

Post Office Box 655303 Dallas, Texas 75265

Copyright 2005, Texas Instruments Incorporated