UC2872资料

UC1872

UC2872

UC3872

07/99FEATURES

•Controls Different Types of Lamps:Cold Cathode Fluorescent, Neon, andGas Discharge

•Zero Voltage Switching (ZVS) ofPush-Pull Drivers

•Accurate Control of Lamp Current

•Variable Lamp Intensity Control

•1µA Disable Current

•4.5V to 24V Operation

•Open Lamp Detection CircuitryDESCRIPTION

TheUC3872isaresonantlampballastcontrolleroptimizedfordriving

coldcathodefluorescent,neon,andothergasdischargelamps.Theres-

onantpowerstagedevelopsasinusoidallampdrivevoltage,andmini-

mizesswitchinglossandEMIgeneration.Lampintensityadjustmentis

accomplishedwithabuckregulator,whichissynchronizedtotheexternal

powerstage’sresonantfrequency.Suitableforautomotiveandbattery

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

Softstartandopenlampdetectcircuitryhavebeenincorporatedtomini-

mizecomponentstresses.Openlampdetectionisenabledatthecomple-

tionofasoftstartcycle.Thechipisoptimizedforsmoothdutycycle

control to 100%.

Otherfeaturesincludeaprecision1.2%reference,undervoltagelockout,

and accurate minimum and maximum frequency control.

Resonant Lamp Ballast Controller

4

6

53

2

12

131

147

8+–

0.5VSYNCOUTSENSEOSCILLATOR

GND+––

+OPENLAMPDETECT+–

+–UVLO3.0VREF10

9

11

R

STTOGGLE50k

50k

50kPUSHPULLOUTPUTSN-CHANNELVC

AOUT

BOUT

COUT

PGND0.1V

PWM1

0.2V200µA

ZERODETECT

ZDCTSSINVCOMPENBLREFVCC

1.5V20µA(HIGH=ENABLE)

BUCKDRIVEP-CHANNELEABLOCK DIAGRAM

UDG-99112Note:Pin numbers shown are for DIP package.application

INFO

available元器件交易网www.cecb2b.comUC1872

UC2872

UC3872

ELECTRICAL CHARACTERISTICS:Unless otherwise stated, these parameters apply for TJ=−55°C to +125°C for theUC1872, –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.

PARAMETERTEST CONDITIONSMINTYPMAXUNITS

Reference Section

Output VoltageTJ= 25°C2.9633.0003.037V

Over Temperature2.9403.0003.060V

Line RegulationVCC = 4.75V to 18V10mV

Load RegulationIO= 0 to−5mA10mV

Oscillator Section

Free Running FrequencyTJ= 25°C576878kHz

Maximum Synchronization FrequencyTJ= 25°C160200240kHz

Charge CurrentVCT= 1.5V180200220µA

Voltage Stability2%

Temperature Stability48%

Zero Detect Threshold0.460.50.56V

Error Amp Section

Input VoltageVO= 2V1.4451.4751.505V

Input Bias Current−0.4−2µA

Open Loop GainVO= 0.5 to 3V6590dB

Output HighVINV= 1.3V3.13.53.9VABSOLUTE MAXIMUM RATINGS

Analog Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . .−0.3 to +10VVCC, VC Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+24VZD Input CurrentHigh Impedance Source. . . . . . . . . . . . . . . . . . . . . .+10mAZD Input VoltageLow Impedance Source. . . . . . . . . . . . . . . . . . . . . . . .+24VPower Dissipation at TA= 25°C. . . . . . . . . . . . . . . . . . . . . .1WStorage Temperature. . . . . . . . . . . . . . . . . . .−65°C to +150°CLead Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300°C

Note1:Currentsarepositiveinto,negativeoutofthespecifiedterminal.

Note2:ConsultPackagingSectionofDatabookforthermallimi-tations and considerations of package.

DIL-14 (TOP VIEW)

N PackagePLCC-20 (Top View)

Q PackageCONNECTION DIAGRAMS

SOIC-16,SSOP-16 (TOP VIEW)DW,M Package元器件交易网www.cecb2b.comUC1872

UC2872

UC3872

ELECTRICAL CHARACTERISTICS:Unless otherwise stated, these parameters apply for TJ=−55°C to +125°C for theUC1872, –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.

PARAMETERTEST CONDITIONSMINTYPMAXUNITS

Error Amp Section (cont.)

Output LowVINV= 1.7V0.10.2V

Output Source CurrentVINV= 1.3V, VO= 2V–350–500µA

Output Sink CurrentVINV= 1.7V, VO= 2V1020mA

Common Mode Range0VIN-1VV

Unity Gain BandwidthTJ= 25°C (Note 4)1MHz

Open Lamp Detect Section

Soft Start ThresholdVINV= 0V2.93.43.8V

Open Lamp Detect ThresholdVSS= 4.2V0.61.01.4V

Soft Start CurrentVSS= 2V102040µA

Output Section

Output Low LevelIOUT= 0, Outputs A and B0.050.2V

IOUT= 10mA0.10.4V

IOUT= 100mA1.52.2V

Output High LevelIOUT= 0, Output C13.914.9V

IOUT=−10mA13.514.3V

IOUT=−100mA12.513.5V

Rise TimeTJ= 25°C, Cl = 1nF (Note 4)3080ns

Fall TimeTJ= 25°C, Cl = 1nF (Note 4)3080ns

Output Dynamics

Out A and B Duty Cycle4849.950%

Out C Max Duty CycleVINV= 1V100%

Out C Min Duty CycleVINV= 2V0%

Under Voltage Lockout Section

Startup Threshold Voltage3.74.24.5V

Hysteresis120200280mV

Enable Section

Input High Threshold2V

Input Low Threshold0.8V

Input CurrentVENBL= 5V150400µA

Supply Current Section

VCC Supply CurrentVCC = 24V614mA

VC Supply CurrentVC = 24V512mA

ICC DisabledVCC = 24V, VENBL= 0V110µA

Note3:Unlessotherwisespecified,allvoltagesarewithrespecttoground.Currentsarepositiveinto,andnegativeoutofthespecified terminal.

Note 4:Guaranteed by design.Not 100% tested in production.元器件交易网www.cecb2b.com