Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - lighting/front end device controller Electric ballast controller SOIC 16 Surface-mount

UC1872

UC2872

UC3872

07/99

FEATURES

•

Controls Different Types of Lamps:

Cold Cathode Fluorescent, Neon, and

Gas Discharge

•

Zero Voltage Switching (ZVS) of

Push-Pull Drivers

•

Accurate Control of Lamp Current

•

Variable Lamp Intensity Control

•

1µA Disable Current

•

4.5V to 24V Operation

•

Open Lamp Detection Circuitry

DESCRIPTION

The UC3872 is a resonant lamp ballast controller optimized for driving

cold cathode fluorescent, neon, and other gas discharge lamps. The res

onant power stage develops a sinusoidal lamp drive voltage, and mini

mizes switching loss and EMI generation. Lamp intensity adjustment is

accomplished with a buck regulator, which is synchronized to the external

power stage’s resonant frequency. Suitable for automotive and battery

powered applications, the UC3872 draws only 1µA when disabled.

Soft start and open lamp detect circuitry have been incorporated to mini

mize component stresses. Open lamp detection is enabled at the comple

tion of a soft start cycle. The chip is optimized for smooth duty cycle

control to 100%.

Other features include a precision 1.2% reference, undervoltage lockout,

and accurate minimum and maximum frequency control.

Resonant Lamp Ballast Controller

–

0.5V

SYNC

OUT

SENSE

OSCILLATOR

GND

–

OPEN

LAMP

DETECT

–

UVLO

3.0V

REF

TOGGLE

50k

PUSH PULL

OUTPUTS

N-CHANNEL

AOUT

BOUT

COUT

PGND

0.1V

PWM

0.2V

200µA

ZERO DETECT

INV

COMP

ENBL

REF

VCC

1.5V

20µA

(HIGH=ENABLE)

BUCK DRIVE

P-CHANNEL

BLOCK DIAGRAM

UDG-99112

Note: Pin numbers shown are for DIP package.

application

INFO

available

Summary of content (11 pages)

PAGE 1
application INFO available UC1872 UC2872 UC3872 Resonant Lamp Ballast Controller FEATURES DESCRIPTION • Controls Different Types of Lamps: Cold Cathode Fluorescent, Neon, and Gas Discharge The UC3872 is a resonant lamp ballast controller optimized for driving cold cathode fluorescent, neon, and other gas discharge lamps. The resonant power stage develops a sinusoidal lamp drive voltage, and minimizes switching loss and EMI generation.
PAGE 2
UC1872 UC2872 UC3872 CONNECTION DIAGRAMS ABSOLUTE MAXIMUM RATINGS Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 to +10V VCC, VC Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +24V ZD Input Current High Impedance Source . . . . . . . . . . . . . . . . . . . . . . +10mA ZD Input Voltage Low Impedance Source . . . . . . . . . . . . . . . . . . . . . . . . +24V Power Dissipation at TA = 25° C . . . . . . . . . . . . . . . . . . . . . .
PAGE 3
UC1872 UC2872 UC3872 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these parameters apply for TJ = −55° C to +125°C for the UC1872, –40° C to +85° C for the UC2872, −0°C to +70°C for the UC3872; VCC= 5V, VC = 15V, VENBL = 5V, CT = 1nF, ZD = 1V. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Error Amp Section (cont.) Output Low VINV = 1.7V 0.1 0.2 V Output Source Current VINV = 1.3V, VO = 2V –350 –500 µA Output Sink Current VINV = 1.
PAGE 4
UC1872 UC2872 UC3872 PIN DESCRIPTIONS AOUT, BOUT: These outputs provide complementary drive signals for the push-pull N-channel MOSFETs. Each one is high for 50% of the time, switching states each time a zero-detect is sensed. INV: This pin is the inverting input to the error amplifier and the input for the open lamp detect circuitry. If the voltage at INV is below the 1V open lamp detect threshold, the outputs are disabled. COMP: COMP is the output terminal of the error amplifier.
PAGE 5
UC1872 UC2872 UC3872 APPLICATION INFORMATION (cont.) A unique protection feature incorporated in the UC3872 is the Open Lamp Detect circuit. An open lamp interrupts the current feedback loop and causes very high secondary voltage. Operation in this mode will usually breakdown the transformer’s insulation, causing permanent damage to the converter.
PAGE 6
UC1872 UC2872 UC3872 APPLICATIONS INFORMATION 0.1V 200µA CT 7 3.0V MAX FREQ COMPARATOR 1.0V ZD 8 0.5V + – DISCHARGE COMPARATOR MIN FREQ COMPARATOR + – Q S 4mA + – – + R CLK ZERO DETECT UDG-99005 Figure 2. UC3872 oscillator section. Figure 3. UC3872 open lamp detect circuitry. UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL.
PAGE 7
PACKAGE OPTION ADDENDUM www.ti.
PAGE 8
PACKAGE OPTION ADDENDUM www.ti.com 4-May-2009 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.
PAGE 9
PACKAGE MATERIALS INFORMATION www.ti.com 29-Jul-2008 TAPE AND REEL INFORMATION *All dimensions are nominal Device UC2872DWTR Package Package Pins Type Drawing SOIC SPQ Reel Reel Diameter Width (mm) W1 (mm) A0 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant DW 16 2000 330.0 16.4 10.85 10.8 2.7 12.0 16.0 Q1 UC3872DWTR SOIC DW 16 2000 330.0 16.4 10.85 10.8 2.7 12.0 16.0 Q1 UC3872MTR SSOP/ QSOP DBQ 16 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.
PAGE 10
PACKAGE MATERIALS INFORMATION www.ti.com 29-Jul-2008 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) UC2872DWTR SOIC DW 16 2000 346.0 346.0 33.0 UC3872DWTR SOIC DW 16 2000 346.0 346.0 33.0 UC3872MTR SSOP/QSOP DBQ 16 2500 346.0 346.0 29.
PAGE 11
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.