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  • UCC2870x Constant-Voltage, Constant-Current Controller With Primary-Side Regulation

    • SLUSB41A July   2012  – December 2014 UCC28700 , UCC28701 , UCC28702 , UCC28703

      PRODUCTION DATA.  

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  • UCC2870x Constant-Voltage, Constant-Current Controller With Primary-Side Regulation
  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Detailed Pin Description
        1. 8.3.1.1 VDD (Device Bias Voltage Supply)
        2. 8.3.1.2 GND (Ground)
        3. 8.3.1.3 VS (Voltage-Sense)
        4. 8.3.1.4 DRV (Gate Drive)
        5. 8.3.1.5 CS (Current Sense)
        6. 8.3.1.6 CBC (Cable Compensation), Pin 1 UCC28700
        7. 8.3.1.7 NTC (NTC Thermistor Shut-down), Pin 1 UCC28701/2/3
      2. 8.3.2 Fault Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Primary-Side Voltage Regulation
      2. 8.4.2 Primary-Side Current Regulation
      3. 8.4.3 Valley-Switching
      4. 8.4.4 Start-Up Operation
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Transformer Parameter Verification
        2. 9.2.2.2 Output Capacitance
        3. 9.2.2.3 VDD Capacitance, CDD
        4. 9.2.2.4 VDD Start-Up Resistance, RSTR
        5. 9.2.2.5 VS Resistor Divider, Line Compensation, and Cable Compensation
        6. 9.2.2.6 Input Bulk Capacitance and Minimum Bulk Voltage
        7. 9.2.2.7 Transformer Turns Ratio, Inductance, Primary-Peak Current
        8. 9.2.2.8 Standby Power Estimate
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Device Nomenclature
        1. 12.1.1.1  Capacitance Terms in Farads
        2. 12.1.1.2  Duty Cycle Terms
        3. 12.1.1.3  Frequency Terms in Hertz
        4. 12.1.1.4  Current Terms in Amperes
        5. 12.1.1.5  Current and Voltage Scaling Terms
        6. 12.1.1.6  Transformer Terms
        7. 12.1.1.7  Power Terms in Watts
        8. 12.1.1.8  Resistance Terms in Ω
        9. 12.1.1.9  Timing Terms in Seconds
        10. 12.1.1.10 Voltage Terms in Volts
        11. 12.1.1.11 AC Voltage Terms in VRMS
        12. 12.1.1.12 Efficiency Terms
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
      2. 12.2.2 Related Links
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
  14. IMPORTANT NOTICE

Package Options

Mechanical Data (Package|Pins)
  • DBV|6
    • MPDS026Q
Thermal pad, mechanical data (Package|Pins)
Orderable Information
  • slusb41a_oa
  • slusb41a_pm
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DATA SHEET

UCC2870x Constant-Voltage, Constant-Current Controller With Primary-Side Regulation

1 Features

  • < 30-mW No-Load Power for 5-Star Rating
  • Primary-Side Regulation (PSR) Eliminates Opto-Coupler
  • ±5% Voltage and Current Regulation
  • 130-kHz Maximum Switching Frequency Enables High-Power Density Charger Designs
  • Quasi-Resonant Valley-Switching Operation for Highest Overall Efficiency
  • Patent-Pending Frequency-Jitter Scheme to Ease EMI Compliance
  • Wide VDD Range Allows Small Bias Capacitor
  • Clamped Gate-Drive Output for MOSFET
  • Protection Functions: Overvoltage, Low-Line, and Overcurrent
  • Programmable Cable Compensation (UCC28700 Only)
  • NTC Resistor Interface (UCC28701, UCC28702 and UCC28703 Only) With Fixed Cable Compensation Options
  • SOT-23 Package

2 Applications

  • USB-Compliant Adapters and Chargers for Consumer Electronics (Cell Phones, Tablets and Cameras)
  • AC and DC Power Supplies

3 Description

The UCC28700 family of flyback power supply controllers provides Constant-Voltage (CV) and Constant-Current (CC) output regulation without the use of an optical coupler. The devices process information from the primary power switch and an auxiliary flyback winding for precise control of output voltage and current. Low start-up current, dynamically controlled operating states and a tailored modulation profile support very low standby power without sacrificing start-up time or output transient response.

Control algorithms in the UCC28700 family allow operating efficiencies to meet or exceed applicable standards. The output drive interfaces to a MOSFET power switch. Discontinuous Conduction Mode (DCM) with valley switching reduces switching losses. Modulation of switching frequency and primary current peak amplitude (FM and AM) keeps the conversion efficiency high across the entire load and line ranges.

The controllers have a maximum switching frequency of 130 kHz and always maintain control of the peak-primary current in the transformer. Protection features help keep primary and secondary component stresses in check. The UCC28700 allows the level of cable compensation to be programmed. The UCC28701, UCC28702, and UCC28703 devices allow remote temperature sensing using a Negative Temperature Coefficient (NTC) resistor while providing fixed cable-compensation levels.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
UCC28700 SOT-23 (6) 2.90 mm × 1.60 mm
UCC28701
UCC28702
UCC28703
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Typical Application Schematic

app1_slusb41.gif

4 Revision History

Changes from * Revision (July 2012) to A Revision

  • Added Handling Rating table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section Go

5 Device Comparison Table(1)(2)

PART NUMBER VERSION
UCC28700 Programmable cable compensation
UCC28701 NTC, 0 mV (at 5-V output) cable compensation option
UCC28702 NTC, 150 mV (at 5-V output) cable compensation option
UCC28703 NTC, 300 mV (at 5-V output) cable compensation option
(1) See Addendum for specific device ordering information.
(2) For other fixed cable compensation options, please consult the factory.

6 Pin Configuration and Functions

pin_slusb41.gif

Pin Functions

PIN I/O DESCRIPTION
NAME UCC28700 UCC28701/2/3
NO. NO.
CBC 1 — I Cable Compensation (CBC) is a programming pin for compensation of cable voltage drop. Cable compensation is programmed with a resistor to GND.
CS 4 4 I Current Sense (CS) input connects to a ground-referenced current-sense resistor in series with the power switch. The resulting voltage is used to monitor and control the peak primary current. A series resistor can be added to this pin to compensate the peak switch current levels as the AC-mains input varies.
DRV 3 3 O Drive (DRV) is an output used to drive the gate of an external high voltage MOSFET switching transistor.
GND 5 5 — The Ground (GND) pin is both the reference pin for the controller and the low-side return for the drive output. Special care should be taken to return all AC decoupling capacitors as close as possible to this pin and avoid any common trace length with analog signal return paths.
NTC — 1 I NTC is an interface to an external NTC (negative temperature coefficient) resistor for remote temperature sensing. Pulling this pin low shuts down PWM action.
VDD 2 2 — VDD is the bias supply input pin to the controller. A carefully-placed bypass capacitor to GND is required on this pin.
VS 6 6 I Voltage Sense (VS) is an input used to provide voltage and timing feedback to the controller. This pin is connected to a voltage divider between an auxiliary winding and GND. The value of the upper resistor of this divider is used to program the AC-mains run and stop thresholds and line compensation at the CS pin.

7 Specifications

7.1 Absolute Maximum Ratings(1)

over operating free-air temperature range (unless otherwise noted)
MIN MAX UNIT
Bias supply voltage VVDD 38 V
Continuous gate current sink IDRV 50 mA
Continuous gate current source IDRV Self-limiting
Peak VS pin current IVS −1.2
Gate-drive voltage at DRV VDRV −0.5 Self-limiting V
Voltage range VS −0.75 7
CS, CBC (UCC28700),
NTC (UCC28701/2/3)		 −0.5 5
Operating junction temperature range TJ −55 150 °C
Lead temperature 0.6 mm from case for 10 seconds 260
Storage temperature, Tstg –65 150 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltages are with respect to GND. Currents are positive into, negative out of the specified terminal. These ratings apply over the operating ambient temperature ranges unless otherwise noted.

7.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±500
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

7.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN MAX UNIT
VDD Bias supply operating voltage 9 35 V
CVDD VDD bypass capacitor 0.047 1 µF
RCBC Cable-compensation resistance 10 kΩ
IVS VS pin current −1 mA
TJ Operating junction temperature −20 125 °C

7.4 Thermal Information

THERMAL METRIC(1) UCC2870x UNIT
DBV
6 PINS
θJA Junction-to-ambient thermal resistance(2) 180 °C/W
θJCtop Junction-to-case (top) thermal resistance(3) 71.2
θJB Junction-to-board thermal resistance(4) 44.4
ψJT Junction-to-top characterization parameter(5) 5.1
ψJB Junction-to-board characterization parameter(6) 43.8
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
(2) The junction-to-ambient thermal resistance under natural convection is obtained in a simulation on a JEDEC-standard, high-K board, as specified in JESD51-7, in an environment described in JESD51-2a.
(3) The junction-to-case (top) thermal resistance is obtained by simulating a cold plate test on the package top. No specific JEDEC-standard test exists, but a close description can be found in the ANSI SEMI standard G30-88.
(4) The junction-to-board thermal resistance is obtained by simulating in an environment with a ring cold plate fixture to control the PCB temperature, as described in JESD51-8.
(5) The junction-to-top characterization parameter, ψJT, estimates the junction temperature of a device in a real system and is extracted from the simulation data for obtaining RθJA, using a procedure described in JESD51-2a (sections 6 and 7).
(6) The junction-to-board characterization parameter, ψJB, estimates the junction temperature of a device in a real system and is extracted from the simulation data for obtaining RθJA, using a procedure described in JESD51-2a (sections 6 and 7).

7.5 Electrical Characteristics

over operating free-air temperature range, VDD = 25 V, RCBC = RNTC = open, –20°C ≤ TA ≤ 125°C, TJ = TA
(unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
BIAS SUPPLY INPUT
IRUN Supply current, run IDRV = 0, run state 2.1 2.65 mA
IWAIT Supply current, wait IDRV = 0, wait state 85 110 µA
ISTART Supply current, start IDRV = 0, VVDD = 18 V, start state 1 1.5
IFAULT Supply current, fault IDRV = 0, fault state 2.1 2.8 mA
UNDER-VOLTAGE LOCKOUT
VVDD(on) VDD turn-on threshold VVDD low to high 19 21 23 V
VVDD(off) VDD turn-off threshold VVDD high to low 7.7 8.1 8.45
VS INPUT
VVSR Regulating level Measured at no-load condition, TJ = 25°C 4.01 4.05 4.09 V
VVSNC Negative clamp level IVS = -300 µA, volts below ground 190 250 325 mV
IVSB Input bias current VVS = 4 V –0.25 0 0.25 µA
CS INPUT
VCST(max) Max CS threshold voltage VVS = 3.7 V(1) 715 750 775 mV
VCST(min) Min CS threshold voltage VVS = 4.35 V(1) 230 250 270
KAM AM control ratio VCST(max) / VCST(min) 2.75 3.0 3.15 V/V
VCCR constant-current regulating level CC regulation constant 310 319 329 mV
KLC Line compensating current ratio IVSLS = -300 µA, IVSLS / current out of CS pin 23 25 28 A/A
TCSLEB Leading-edge blanking time DRV output duration, VCS = 1 V 195 235 275 ns
DRV
IDRS DRV source current VDRV = 8 V, VVDD = 9 V 20 25 mA
RDRVLS DRV low-side drive resistance IDRV = 10 mA 6 12 Ω
VDRCL DRV clamp voltage VVDD = 35 V 14 16 V
RDRVSS DRV pull-down in start state 150 200 230 kΩ
PROTECTION
VOVP Over-voltage threshold At VS input, TJ = 25°C 4.52 4.6 4.68 V
VOCP Over-current threshold At CS input 1.4 1.5 1.6
IVSL(run) VS line-sense run current Current out of VS pin – increasing 190 220 260 µA
IVSL(stop) VS line-sense stop current Current out of VS pin – decreasing 70 80 95
KVSL VS line-sense ratio IVSL(run) / IVSL(stop) 2.5 2.8 3.05 A/A
TJ(stop) Thermal shut-down temperature Internal junction temperature 165 °C
CABLE COMPENSATION (UCC28700 ONLY)
VCBC(max) Cable compensation maximum voltage Voltage at CBC at full load 2.8 3.0 3.4 V
VCVS(min) Compensation at VS VCBC = open, change in VS regulating level at full load –45 –15 25 mV
VCVS(max) Maximum compensation at VS VCBC = 0 V, change in VS regulating level at full load 275 320 365
CABLE COMPENSATION (UCC28701, UCC28702, AND UCC28703 ONLY)
VCVS Compensation at VS (UCC28701) Change in VS regulating level at full load –45 –15 25 mV
VCVS Compensation at VS (UCC28702) Change in VS regulating level at full load 100
VCVS Compensation at VS (UCC28703) Change in VS regulating level at full load 200
NTC INPUT (UCC28701, UCC28702, AND UCC28703 ONLY)
VNTCTH NTC shut-down threshold Fault UVLO cycle when below this threshold 0.95 V
INTC NTC pull-up current Current out of pin 105 µA
(1) These devices automatically vary the control frequency and current sense thresholds to improve EMI performance, these threshold voltages and frequency limits represent average levels.

7.6 Switching Characteristics

over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
fSW(max) Maximum switching frequency VVS = 3.7 V(1) 120 130 140 kHz
fSW(min) Minimum switching frequency VVS = 4.35 V(1) 875 1000 1100 Hz
TZTO Zero-crossing timeout delay 1.8 2.1 2.45 µs

7.7 Typical Characteristics

At VDD = 25 V, unless otherwise noted.
SLUSB41_Figure 1.pngFigure 1. Bias Supply Current vs. Bias Supply Voltage
SLUSB41_Figure 3.pngFigure 3. VS Regulation Voltage vs. Temperature
SLUSB41_Figure 5.pngFigure 5. Minimum CS Threshold Voltage vs. Temperature
SLUSB41_Figure 7.png
Figure 7. Minimum Switching Frequency vs. Temperature
SLUSB41_Figure 9.pngFigure 9. NTC Shutdown Threshold Voltage vs. Temperature
SLUSB41_Figure 11.pngFigure 11. Overvoltage Threshold vs. Temperature
SLUSB41_Figure 2.pngFigure 2. Bias Supply Current vs. Temperature
SLUSB41_Figure 4.pngFigure 4. Line-Sense Current vs. Temperature
SLUSB41_Figure 6.pngFigure 6. Constant-Current Regulating Level vs. Temperature
SLUSB41_Figure12.gif
VDRV = 8 V, VVDD = 9 V
Figure 8. DRV Source Current vs. Temperature
SLUSB41_Figure 10.pngFigure 10. NTC Pullup Current vs. Temperature

 
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