LR5810 LR5810 Description The LR5810 series switc her ICs cost effectively rep lace all power supplies up to 5W output power based on unregulated is olated linear transformer (50/ 60HZ). Unlike conventional PWM (pulse width modulation) controllers, they regulate the output voltage in a ne w method of off-time modulation control. The co ntroller consists of a VCO (voltage control oscillator), Sense and logic circuit, VDD pin, under -voltage lockout circuit, protection for over-voltage, current lim ited circ uit, lead ing edge blanking, over load protection and fault condition auto-restart. They are ideal low power AC/DC adapter/charger solution for portable devices, Features • Low start-up current: Typ.15 µA Max.25 µA • UVLO(under voltage lockout):Typ.12V start- up Typ.6V shut-down • Low operating current:Typ.2 mA Max.5 mA • LEB(leading edge b lanking): Typ.300ns • OVP(over voltage protection) : Typ.28 V • Operation Frequency : Typ.54KHZ(VDD=21V) • Output Driver Ab ility: Typ.15 mA • OLP(over load protection) • Universal AC input range • Constant voltage and constant current • Small SOT-23-6 and SOP-8 package. Applications ？ AC/DC adapter/charger for cell/cordless phones, digital cameras, MP3/portable audio devices etc • LED Lighting • Replacements for linear transfo rmers and RCC SMTPS Package 1 LR5810 Application Circuit 2 L 1mH + - 4 AC 85V~264V 1 15R 1 221_1KV BR 1 3 10R 47uF _400V 47uF _400V N + 6 + 200K 1nF _1KV + +5V_1A SB330 + 1.8M + 1000 uF_6. 3V 2 F R107 4.7uF _6.3V 270R 3 1.8M 5 + 4 IN4148 7.5M NC VD D GN D Vout 6 3 1 5 2 1 2 3 Sens e NC 4 1.5K LR5810 2R 2 2R 2 1uF SOT23-6 Application Circuit 2 L D2 4 + - AC 85V~264V 3 1n F_1 KV + 200K + 221_1KV 6 + 270 R 2 FR107 4.7uF_10V + +5V_1A + 1000u F_10 V 1.8M 4.7u F_4 00V 10R 15R 1 1mH BR 1 4.7u F_4 00V N L2 1 7.5M 1.8M 3 5 + 4 IN4148 1 2 3 4 VDD GND NC GND Sense OE OC OC 8 7 6 5 LR 5810 1.5K 1u F_25 V 2R2 2R2 SOP-8 Application Circuit 2 LR5810 Block Diagram Pin Connection (Top View) Package Package Function Description PIN 1: NC Not Connected PIN 2: GND Ground PIN 3: Sense Current sensor,it senses the voltage via a sensed resistor PIN 4: NC Not Connected PIN 5: Vout Gate drive output for the external power BJT switch. PIN 6: VDD Power Supply Function Description PIN 1: VDD Power Supply PIN 2: NC Not Connected PIN 3: Sense Current sensor,it senses the voltage via a sensed resistor PIN 4: OE Emmiter Pin of the power BJT switch. PIN 5、6: OC Output Pin( Connect to switching transformer) PIN 7、8: GND Ground 3 LR5810 Function Description 1. Under Voltage Lockout The turn-on and turn-off thresholds of the LR5810 are fix ed internally at 12V/6V. During start- up, the hold-up capacitor must be charger to 12 V through the start- up resistor, so that the LR5810 can be enabled. The hold-up capacitor will continue to supply VDD until power can be delivered from the auxilia ry winding of the main ransformer, When VDD drop below 6V, IC will be shut-down, and have to start-up again. This UVLO hysteretic window ensures that LR5810 can start-up very well. 2. Leading Edge Blanking When th e power BJT is switched on, a volt age spike will inevit ably occur at the sense pin. To avoid prematur e termination of the switching pu lse, a 300 ns lead ing -edge b lanking time is built in LR5810. Conventional RC filtering can be omitted. During this blanking per iod, the current-limit comparator is disabled and it cannot switch off the gate driv er. 3. Voltage Control Oscillator The sense circuit of LR5810 ser ies will sense the vo ltage of VDD p in (also the power pin of LR5810) and then control the frequency of the oscillato r. The max frequenc y of LR5810 series is set to the rated output power point,for examp le L R5810 is set to 54 KHZ Two signals are generated from the oscillator: the maximum duty c ycle signal (DC max) and the clock signal th at ind icates the beg inning of each switching c ycle. 4. Sense Circuit A resistor vo ltage d ivid ed circuit is connected between the VDD p in and GND p in in order to sample th e feed-back volta ge at VDD p in. When the vo ltag e of VDD p in exceeds 21V, IC will come into constant vo ltag e control mode,shut- down the output pin and start a bypass circuit. This bypass circ uit is linear ly c ontrolled by the feedback voltage. When th e vo ltage of VDD p in falls below 21V, the off-tim e linearly increases in order to have a constant current output. 5. Gate Output Unlike other chips, LR5810 used a constant current circ u it to drive the output BJT. The output current is fixed at 15mA, select the appropriate HFE of BJT could have a differe nt output power. 6. Fault Condition Auto-restart In the event of a fault condition such as output over- load or short c ircu it, LR5810 series enter into auto-restart operation. It is us ing the turn-on and turn-off threshold again. LR5810 series are working in start mode to protect the s ystem from damage caused by the fault condition. 7. Current Limit The current through the power BJT is detected by the current limit circuit. Then the current flows through the sense-resistor and ma kes the vo ltage on Sense pin ra mp up. And when this vo ltag e e xceeds the int ernal threshold (Vlimit), the p ower BJT is turn ed off immed iately. 4 LR5810 Electrical Characteristic Item Conditions MIN. TYP. MAX. Unit 25 uA Supply Voltage Start-up Current VDD=VDD(ON)-0.1 15 Operation Voltage 25℃ 21 Turn-on Threshold Voltage VDD ON 11 12 13 V Turn-off Threshold Voltage VDD OFF 5.5 6 6.5 V Over-voltage Thershold Vovp 28 30 V 50 55 KHZ 75 % V Oscillator Operation Frequency 25℃ Duty Cycle Vsense=0 Green Mode Frequency 25℃ 15 20 25 KHZ Leading Edge Blanking 25℃ 250 300 350 nS Current Sense Detection Voltage VDD=15V 0.45 0.5 0.55 V 45 Current Sensing Else Output Delay Time 25℃ Output Driver Current 25℃ 150 12 15 nS 18 mA Absolute Maximum Ratings Attention: Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. Ordering info LR5810-AL LR5810-BL SOT-26 SOP-8 内置三极管 13003 5 LR5810 SOT-26 Dimension SOP-8 Dimension Symbol A A1 Dimensions In Millimeters Min. Nom. Max. 1.40 1.60 1.75 0.10 0.25 Dimensions In Inches Min. Nom. Max. 0.055 0.063 0.069 0.040 0.100 A2 1.30 1.45 1.50 0.051 0.057 0.059 B C 0.33 0.19 0.41 0.20 0.51 0.25 0.013 0.0075 0.016 0.008 0.020 0.010 D E 4.80 3.70 5.05 3.90 5.30 4.10 0.189 0.146 0.199 0.154 0.209 0.161 e - 1.27 - - 0.050 - H L 5.79 0.38 5.99 0.71 6.20 1.27 0.228 0.015 0.236 0.028 0.244 0.050 y ? 0° - 0.10 8° 0° - 0.004 8° 6