PT4213
Primary Side CC Controller
GENERAL DESCRIPTION
液体收集系统The PT4213 is a primary side regulated constant current controller, which is designed for LED lighting applications. The device regulates output current without the secondary feedback loop. The device integrates an oscillator, a current sense circuit, CC control circuit, a pre-driver and a complete set of protection circuits to protect against all fault conditions including output open/short circuit, line under-voltage, and over temperature protection. The PT4213 is available in SOT23-6 package. FEATURES
CC Without Secondary Feedback Inductance Compensation Low Startup Current (<10uA) Adjustable Primary Side Current limit VCC/FB Over Voltage Protection VCC/FB UVLO Feedback Loop Open Circuit Protection Over Temperature Protection RoHS compliant
APPLICATIONS
Off-line High Brightness General LED Lighting Integrated LED Lamps such as GU10, E27, PAR20/20/38 LED Lamps
ORDERING INFORMATION
PACKAGE
SOT23-6， free Pb
TEMPERATURE RANGE
-40℃ to 85℃
ORDERING PART NUMBER
rgd-208PT4213E23F
TRANSPORT MEDIA
3000/Tape and Reel
MARKING
4213
TYPICAL APPLICATION CIRCUIT
D2
LED+
C4
AC IN 85～265V
C1
R2
C2
钟罩阀LEDR1 D1
T1
R5 R3
D3
Q1
VCC FB GATE CS
R6
PT4213
R4
C3
GND
China Resources Powtech (shanghai) Co. Ltd
PT4213_DSB Rev EN1.0
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PT4213
Primary Side CC Controller
PIN ASSIGNMENT
PIN DESCRIPTIONS
PIN No. 1 2 3 4 5 6 PIN NAMES CS GND NC GATE VCC FB DESCRIPTION Primary Side Current Sense Input Ground Not connected Drive output Power supply, the device is supplied by an auxiliary winding. Auxiliary Winding Voltage Sense Input
ABSOLUTE MAXIMUM RATINGS (note1)
SYM PARAMETER VALUE UNIT
VCC VFB VCS VGATE Topt Tstg ESD
RΘJA
VCC pin Voltage FB pin Input Voltage CS pin Voltage GATE pin output voltage Operating Junction Temp. Range Storage Temp. Range HBM
SOT23-6
-0.3~30 -0.3~5 -0.3~5 -0.3~15 -40 to 150 -55 to 150 2000
250
V V V V ℃ ℃ V
℃/W
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Recommended Operating Range indicates conditions for which the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Range. Specifications are not guaranteed for param
eters where no limit is given, however, the typical value is a good indication of device performance.
RECOMMENDED OPERATING RANGE
SYM PARAMETER VALUE UNIT
VCC TA
VCC pin Operating Voltage Operating Ambient Temperature
9.5~26 -20~85
V ℃
China Resources Powtech (shanghai) Co. Ltd
PT4213_DSB Rev EN1.0
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PT4213
Primary Side CC Controller
ELECTRICAL CHARACTERISTICS
(TA=25℃, VCC=16V，fsw=65KHz unless specified otherwise) SYMBOL PARAMETER TEST CONDITION MIN TYP MAX UNIT
SUPPLY VOLTAGE (VCC) ISTART VVCC_ON VVCC_OFF VVCC_Clamp VVCC_OVP IVCCQ Start up current VCC turn on threshold VCC minimum voltage operating VCC=12.0V VCC Rising VCC Falling Icc=10mA 26 No switching 12.5 7.5 1 14.0 8.5 33 27.5 350 29 700 10 15.5 9.5 uA V V V V uA
VCC Clamp Voltage VCC Over Voltage Protection Threshold VCC Supply Current
FEED BACK VOLTAGE SENSE PIN (FB) VFBMAX VFBMIN IFB_OPEN FB Over Voltage Protection FB Minimum Voltage FB Open Loop Current 2.4 2.5 0.8 -85 2.6 V V uA
CURRENT SENSE INPUT PIN (CS) VCS TLEB Current Limit Threshold Current sense Leading Edge Blanking Time Maximum driving pulse duty cycle Rising time Falling time Gate clamp voltage Cgate=1nF Cgate=1nF Ifb=0 490 500 250 510 mV nS
DRIVE OUTPUT (GATE) Dmax Tr Tf VGS_MAX PROTECTION TSD Thermal Threshold Shut Down 150 ℃ 65 220 120 15 % nS nS V
China Resources Powtech (shanghai) Co. Ltd
PT4213_DSB Rev EN1.0
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PT4213
Primary Side CC Controller
SIMPLIFIED BLOCK DIAGRAM
OPERATION DESCRIPTION The PT4213 consists of an oscillator, feedback circuit, over-temperature protection, frequency jittering, current limit circuit, leading-edge blanking, and constant current control circuitry. The switching frequency is modulated to regulate the output current to provid
e a constant current characteristic. It senses and regulates output current from primary side of transformer and is ideal for high precise, high reliability and cost effective LED lighting application. THEORY OF OPERATION
Figure 1 illustrates a simplified flyback converter. When the switch Q1 turns on, the voltage across the primary winding is Vbus. Assuming the voltage dropped across Q1 is zero, the current in Q1 ramps up linearly at a rate of Vbus/Lp. When the current in Q1 reaches a predefined value of Ipk_pri the controller forces Q1 turns off. During the Q1 on-time, the rectifying diode D2 is reverse biased and the load current Io is supplied by the secondary capacitor C4. When Q1 turns off, D2 conducts and the stored energy is delivered to the output. The PT4213 is designed to operate in discontinuous conduction mode (DCM), in DCM the energy stored in primary winding is transported to the secondary winding completely during each cycle. The output current is determined by Rcs and primary/secondary turns ratio of the transformer. Assuming the transformer primary/secondary turns ratio is Nps. The output current is given by following expression:
China Resources Powtech (shanghai) Co. Ltd
PT4213_DSB Rev EN1.0
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PT4213
Primary Side CC Controller
I out = 0.1125 * N ps Rcs
source terminal and GND and feeds to CS input. At each switching cycle when the voltage of CS input excess the internal threshold the driving signal is terminated after a short delay. The relationship between the CS threshold and the primary peak current passing through power MOSFET Q1 follows below expression: Ipk_pri=Vcs/Rcs; Ipk_pri is the peak current through power MOSFET, VCS is the voltage threshold of pin1 of PT4213 and Rcs represents sensing resistor. A spike is inevitable on the sensed signal on Rcs at the instance when the power MOSFET is turned on due to the recovery time of the secondary rectifier and the snubber circuit. The LEB has been implemented in PT4213, during the LEB time the current sense comparator is disabled so the switching signal can not be terminated by the turn-on spike on the sensed signal so the external RC filter can be removed.
START UP Once the AC voltage is applied to the application circuit, the Vbus charges VCC pin up through the start up resistor R1, when the voltage on VCC pin reaches its VCC_ON threshold the controller starts to deliver the driving pulses to power switch Q1 and VCC is powered by auxiliary winding. Thanks to the very small start up current, a large start up resistor R1 could be used in the start up circuit to minimize power loss. For the applications with general 90-264Vac input range, a 1/8W resistor between 0.5Mohm and 3Mohm and a 4.7uF/50V capacitor C3 compose a simple and reliable start up circuit.
CURRENT LIMIT COMPENSATION CONSTANT CURRENT (CC) OPERATION The PT4213 regulates output current from the primary side control. The switching frequency is adjusted as the feedback pin voltage increases to provide a constant output current regulation. PRIMARY INDUCTANCE COMPENSATION With the inductance compensation function output current is free of primary inductance variation. If the primary magnetizing inductance is either too high or low the converter will automatically adjust the Oscillation frequency to maintain the constant output current. CURRENT SENSE AND LEB The current of the power MOSFET is transferred to voltage signal through a resistor connected between The current limit circuit senses the current in the power MOSFET from the resistor connecting between the source of MOSFET and GND. The current sense
resistor converts the current in the power MOSFET to voltage signal and then feeds to CS pin. When the voltage on CS pin exceeds the internal threshold VCS which is defied as 500mV, the power MOSFET is turned off for the remainder of that cycle. Excellent regulation performance is achieved with C.R.PowTech proprietary line regulation control technique. SHORT CIRCUIT PROTECTION In the event of a fault condition such as an output short condition the PT4213 enters into an appropriate protection mode as described below. In the event the feedback pin voltage falls below 0.8V during the
China Resources Powtech (shanghai) Co. Ltd
PT4213_DSB Rev EN1.0
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