LD7904JGP7 LEADTREND | Alldatasheet
Document overview
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Technical content
Features
Built-in 700V Power MOSFET Built-in High Voltage startup circuit Fixed Switching Frequency at 100KHz Frequency Trembling for EMI improve Internal High Voltage Startup Circuit Under Voltage Lockout (UVLO) on VCC Pin Current Mode Control with Slope Compensation Green-Mode Control for Power Saving OVP / OLP / Internal Thermal Shut Down
Applications
Switching AC/DC Adaptor LCD TV or PC Standby Power SMPS for LCD Monitor Typical Application
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Pin Configuration
Ordering Information
Part number Package Top Mark Shipping LD7904JGP7 DIP-6 Green Package LD7904JGP7 3600/ Tube/ Carton The LD7904JGP7 is ROHS compliant. Protection Mode Switching Freq. VCC OVP OLP Internal OTP 100kHz Auto recovery Auto recovery Auto recovery Pin Descriptions PIN NAME FUNCTION
1 NC NC
2 COMP Feedback control pin, by connecting a photo-coupler and a capacitor to close the
control loop and achieve the stable regulation.
3 GND Ground of the controller
4 S Source terminal of internal power MOSF ET, connecting a sense resistor to ground. 5,6 Drain Drain terminal of the internal power MOSFET
7 NC NC
8 VCC Power supply to Vcc
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Recommended Operating Conditions 230VAC ± 15% 90~264VAC* Product Drain Current Rds(on) Adapter Open Frame Adapter Open Frame LD7904JGP7 4A 2.8 25W 30W 18W 25W * Typ Vcc=12V & Drain Current =2A at Ta =25 C **Calculated maximum Input Power Rating at Ta =25 C Item Min. Max. Unit Supply Voltage Vcc 11 25 V Vcc Capacitor 10 47 F COMP Capacitor Value 2.2 100 nF Note: 1. COMP pin connecting a capacitor is essentia l to filter out the undesired switching noise for stable operation. 2. The small signal components as closed to IC pin as possible. Tj Power Disspation 25C1 2 5 C 1.2W
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Block Diagram COMP internal bias & Vref GND PWM Comparator UVLO On/off Green-Mode Control LEB R R SQ Vref OK PG + Slope Compensation VOVP VCC Vcs-off OLP Delay CounterVOLP OCP Comparator OLP Comparator OLP OVP UVLO Comparator Driver Stage OVP Comparator VCC OK OLP PG Vbias All Blocks OSC OLP Delay Protection Counter R SQ PDR 1mA S R Q In. OTP Drain S
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Absolute Maximum Ratings Supply Voltage VCC -0.3V~30V COMP -0.3V ~7V S pin DC Voltage -0.3V ~7V S pin negative pulse voltage (Duration Time < 100nS) -1.5V Drain -0.3V~700V Peak Pulse drain current 4A Total Maximum Power Dissipation of (25C) 1.25W Package thermal resistance (DIP-6) θJA 80 C/W θJC 30 C/W Operating Junction Temperature Range -40 C to 125C Operating Ambient Temperature Range -20 C to 85C Storage Temperature Range -65 C to 150C Lead temperature (Soldering, 10sec) 260 C ESD Voltage Protection, Human Body Model (Exclusive Drain Pin) 2.5KV ESD Voltage Protection, Machine Model (Exclusive Drain Pin) 250 V Caution: Stresses beyond the ratings specified in “Absolute Maximum R atings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012
Electrical Characteristics
(Ta=25C, VCC=15.0V , unless otherwise stated,) Electrical Characteristics for Control Section PARAMETER CONDITIONS MIN TYP MAX UNITS High Voltage Supply (Drain Pin) High Voltage Current Source VCC<UV LO(on), HV=500V 0.5 1.0 1.5 mA Off State Leakage Current VCC>UVLO(off), HV=500V - 8 35 A Supply Voltage (Vcc Pin) Startup Current 200 300 400 A VCOMP=0V - 1.1 - mA VCOMP=3V - 3.1 - mA OLP Tripped - 0.6 - mA Operating Current OVP Tripped - 0.6 - mA UVLO (off) 8.0 9.0 10.0 V UVLO (on) 15.0 16.0 17.0 V OVP on Vcc Pin 25 27 V Voltage Feedback (Comp Pin) Short Circuit Current V COMP=0V 0.2 0.26 0.32 mA Open Loop Voltage COMP pin open 5.5 6 - V Fixed Frequency Mode - 2.5 - V Green Mode Threshold VCOMP - 2.1 - V Zero Duty Trip Level(off) - 1.6 - V Hysteresis - 100 - mV Current Sense Comparator(Cs Pin) Maximum Input Voltage Vcs_off 0.425 0.45 0.475 V Leading Edge Blanking Time - 380 - ns Slope compensation 0 to max. duty - 150 - mV Input impedance 1 - - M Delay to Output - 100 - ns Oscillator & Control Frequency 94 100 106 kHz Green Mode Frequency 22 25 28 kHz Frequency Trembling fs = 100kHz - ±6.2 - kHz
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 (Ta=25C, VCC=15.0V,Tj=25C , unless otherwise stated,) PARAMETER CONDITIONS MIN TYP MAX UNITS Frequency Temp. Stability -25~85 C - 5 - % Voltage Stability Vcc=11~25V) - - 1 % Maximum Duty - 75 - % OLP (Over Load Protection) OLP Trip Level 4.8 5.0 5.2 V OLP Delay Time - 84 ms Soft Start Soft Start Duration - 4 - ms On Chip OTP OTP Level - 140 - C Hysteresis - 30 - C Electrical Characteristics for MOSFET PARAMETER CONDITIONS MIN TYP MAX UNITS Drain to Source Breakdown Voltage Breakdown Voltage BVDSS Vcc=0V, COMP=0V, I D=250A 700 V Drain on Resistance Drain to S pin On-Resistance I D=2A; VCC=15V; Tj=25C 2.8
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Typical Performance Characteristics UVLO (on) (V) Fig. 1 UVLO (on) vs. Temperature Temperature (C) 14.0 14.8 15.6 16.4 17.2 18.0 -40 0 40 80 120 125 UVLO (off) (V) Temperature (C) Fig. 2 UVLO (off ) vs. Temperature 9.6 10.4 8.8 -40 0 40 80 120 125 11.2 Frequency (KHz) Fig. 3 Frequency vs. Temperature Temperature (C) -40 96 100 102 104 106 0 40 80 120 125 Frequency (KHz) Vcc (V) Fig. 4 Frequency vs. Vcc 12 14 16 18 20 22 24 11 25 102 104 106 frequency (KHz) Vcc (V) Fig. 5 Green mode frequency vs. Vcc 12 14 16 18 20 22 2411 25 Frequency (KHz) T emperature (C) Fig. 6 Green Mode Frequency vs. T emperature -4 0 0 40 80 120 125
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Max Duty (%) Temperature (C) Fig. 7 Max Duty vs. Temperature -40 0 40 80 120 125 VCS (off) (V) Temperature (C) Fig. 8 V CS (off) vs. Temperature 0.43 0.44 0.45 0.46 0.47 0.48 -40 0 40 80 120 125 VCC OVP (V) Temperature (C) Fig. 9 VCC OVP vs. Temperature -40 0 40 80 120 125 VCOMP (V) Temperature (C) Fig. 10 V COMP open loop voltage vs. Temperature -40 04 0 80 120 125 4.5 5.0 5.5 6.0 6.5 7.0 OLP (V) Temperature (C) Fig. 11 OLP-Trip Level vs. Temperature -40 0 40 80 120 125 3.5 4.0 4.5 5.0 5.5 6.0 HV Current Source (mA) Temperature (C) Fig. 12 HV Current Source vs. Temperature (HV=500V, Vcc=0V) 0.7 0.9 1.1 1.3 1.5 -40 0 40 80 120 125
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012
Application Information
The LD7904JGP7 is a green-mode chip and is intended for the modern switching power suppliers and adaptors which demand higher efficiency and low loss. With integrated multi-functions in this chip, the LD7904JGP7 could minimize the external components counts and reduce the product size. The major features are described as below. High Voltage Startup Circuit Traditional PWM controller requires external startup resistor to provide the startup current. However high resistance will take more start up time while low resistance cause more power loss. To optimize the circuit performance and energy saving, the LD7904JGP7 features high voltage startup to enhance the performance. As shown in Fig. 13, During startup, a high-voltage(HV) constant current source (~1mA) sinks current from the Drain pin to provide the PWM IC start current to and Vcc capacitor C1 charge current. In this period the PWM IC only sink 300uA thus most of the HV current is utilized to charge the Vcc capacitor. After the Vcc higher than UVLO(on) threshold, this HV current source will turn off and LD7904JGP7 is start to work then Vcc supply current is provide from the auxiliary winding of the transformer. T herefore, the power losses on the startup circuit can be el iminated and the power saving can be easily achieved. By using such configuration, the turn-on delay time will be almost same no matter low-line or high-line conditions. Whenever the Vcc voltage is higher than UVLO(on). Under Voltage Lockout (UVLO) An UVLO comparator is impl emented in LD7904JGP7 to detect the voltage on the VCC pin. It would assure the supply voltage enough to turn on the LD7904JGP7 PWM controller and further to drive the internal power MOSFET. As shown in Fig. 14, a hysteresis is built in to prevent the shutdown from the voltage dip du ring startup. The turn-on and turn-off threshold level are set at 16.0V and 9.0V, respectively. Fig. 13
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Fig. 14 Current Sensing and Leading-edge Blanking The typical current mode of PWM controller feedbacks both current signal and voltage signal to close the control loop and achieve regulation. The LD7904JGP7 detects the internal MOSFET current from the S pin and pulse-by-pulse limt current. The maximum voltage threshold of the current sensing pin is Vcs_off (~0.45V). The MOSFET peak current can be obtain from below equation. S )MAX(PEAK R off_VcsI Due to integrated leading edge blanking circuit and internal spike filter, it doesn’t need external LC filter parts. Internal Slope Compensation Stability is crucial for current mode control when it operates at CCM and more than 50% of duty-cycle. To stabilize the control loop, the slope compensation is required in the traditional UC384X design by injecting the ramp signal from the RT/CT pin through a coupling capacitor. In the LD7904JGP7, the internal slope compensation circuit has been implemented to simplify the external circuit design. On/Off Control The gate driver of LD7904JGP7 can be disabled immediately by pulling COMP pin voltage level lower than Zero Duty Trip Level. The disable-mode can be released when Comp pin voltage level higher than Zero Duty Trip Level. Oscillator and Switching Frequency The switching frequency of LD7904JGP7 is fixed at 100KHz to provide the optimized operations by considering the EMI performance, thermal treatment, component sizes and transformer design. The Trembling frequency is internally pre-set for 6.2KHz when incorporating with 100KHz switching frequency. Green-Mode Operation By using the green-mode control, the switching frequency can be reduced under the light l oad condition. This feature helps to improve the efficiency in light load conditions. The green-mode control is Leadtrend Technology’s own IP. Maximum Duty-Cycle The maximum duty-cycle of LD7904JGP7 is limited to 75% to avoid the transformer saturation. Voltage Feedback Loop The voltage feedback signal is provided from the TL431 in the secondary side through the photo-coupler to the COMP pin of LD7904JGP7. The input stage of LD7904JGP7, like the UC384X, is incorporated with 2 diodes voltage offset circuit and a voltage divider with 1/6 ratio. Therefore, )V2V(6 1)V FCOMPPWM( COMPARATOR
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 A pull-high resistor is embedded internally and thus an external one is not required. OVP (Over Voltage Protection) on Vcc LD7904JGP7 is implemented an OVP function on Vcc. When the Vcc voltage is higher than the OVP threshold voltage, the output gate drive circuit will be shutdown and stop the switching of the power MOSFET. If fault condition is removed, the LD 7904 will automatic restart at the next UVLO(on). If the fault condition is not removed, at the next UVLO(on) the Vcc will tripped the OVP level again and re-shutdown the output. Then the Vcc is working as a hiccup mode. The Figure 16 shows its operation. Fig. 16 Over Load Protection (OLP) To protect the circuit from being damaged under over load condition or short circuit condition, a OLP function is implemented in the LD7904JGP7. The Figure 17 shows the waveforms of the OLP operation. While OLP condition, the feedback loop will force the Comp pin(V COMP) voltage increase to provide more power to output. When the V COMP trips up to the OLP threshold 5V and stays longer than the OLP delay time, the LD7904JGP7 will turn off the gate output to stop the switching of power circuit. The OLP delay time is to prevent the false trigger from the power-on and turn-off transient. Typically the OLP delay time will be around 83mS. By such protection mechanism, the average input power while OLP can be reduced to very low level so that the component temperature and stress can be controlled within the safe operating area. VCC UVLO(on) UVLO(off) t t COMP OLP 5.0V t OUT 60mS Switching SwitchingNon-Switching OLP trip Level 2nd UVLO(off) OLP Counter Reset Fig. 17 Open/Short fault Protection Some critical protections were integrated in the LD7904JGP7 to prevent the power supply damaged while open/short fault condition. The LD7904JGP7 will shunt down to protect the power circuit under following open or short conditions: 1. COMP pin short to ground 2. S pin floating
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Internal Thermal Shut Down In order to protect IC from thermal damage, when junction temperature is above 140 C the LD7904JGP7 will shut down. While its temperatur e cools down gradually to 110C(Typ.) the LD7904JGP7 will restart again. Power Dissipation and Thermal Management The power supply designer should carefully consider the operating case temperature and operating junction temperature for the LD7904JGP7. The maximum operating junction temperature is 125 C. The switcher should NOT operate in any condition over this limitation. Junction Temp.(T = Case Temp.(Tc) + Power loss * thermal resistance(θJC)
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Reference Application Circuit- 12V/2A Pin <0.1W @Po=0W & AC264Vin
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012
Package Information
S Dimension in Millimeters Dimensions in Inches Symbol Min Max Min Max A 9.017 10.160 0.355 0.400 B 6.096 7.112 0.240 0.280 C 3.600 5.334 0.142 0.210 D 0.356 0.584 0.014 0.023 E 1.143 1.778 0.045 0.070 F 2.337 2.743 0.092 0.108 H 3.175 4.953 0.125 0.195 I 2.921 3.556 0.115 0.140 J 7.366 8.255 0.290 0.325 K 0.230 0.280 0.009 0.011 L 0.325 0.460 0.013 0.018 M 8.509 9.525 0.335 0.375 P 2.750 3.050 0.108 0.120 S 5.842 6.858 0.230 0.270
Leadtrend Technology Corporation www.leadtrend.com.tw LD7904JGP7-DS-00b March 2012 Important Notice Leadtrend Technology Inc. reserves the right to make changes or corrections to its products at any time without notice. Custome rs should verify the datasheets are current and complete before placing order.
Revision History
Rev. Date Change Notice 00 2011/6/17 Original Specification 00a 2011/12/8 Implementation for DIP-6 package information 00b 2012/3/21 (min.)/ (max.) spec for DIP-6 package