preliminary datasheet pwm controller AP3021 aug. 2012 rev. 1. 1 bcd semiconductor manuf acturing limited 1 general description AP3021 is a constant 330khz, voltage mode, external compensation boost controller. the ic has low reference voltage which makes it ideal for low cost led backlight supplies. it can support dc dimming. AP3021 employs complete protection to ensure system security. the device integrates under voltage lockout, over voltage protection, and over temperature protection to protect the circuit. to satisfy the requirements for small mounting space constraints, AP3021 is av ailable in soic-8 package to save space. features ? voltage mode pwm controller ? low feedback voltage: 0.2v ? fixed frequency: 330khz ? dc dimming ? low shutdown current: 0.1 a ? external compensation ? built-in uvlo function ? built-in ovp ? built-in otp applications ? led tv ? led monitor ? led display module figure 1. package type of AP3021 soic-8
preliminary datasheet pwm controller AP3021 aug. 2012 rev. 1. 1 bcd semiconductor manuf acturing limited 2 vdd en comp fb ovp nc gnd out 1 2 3 4 8 7 6 5 pin configuration m package (soic-8) figure 2. pin configurat ion of AP3021 (top view) pin description pin number pin name function 1 vdd supply input pin. a capacitor should be connected between the vdd pin and gnd pin to keep the dc input voltage constant 2 en enable and dimming pin. when en input voltage is lower than 0.3v, disable ic. when en input voltage works at 0.5v to 2.4v, enable dc dimming. when en input voltage is higher than 2.6v, enable ic 3 comp compensation pin. this pin is the output of the internal error amplifier. comp is forced to low when v dd <3.6v 4 fb feedback pin. this pin is connected to an external resistor divider to program the system output voltage 5 ovp over voltage detection pin 6 nc no connection 7 gnd ground pin 8 out output pin, this pin is connected to external mosfet gate to turn it on/off
preliminary datasheet pwm controller AP3021 aug. 2012 rev. 1. 1 bcd semiconductor manuf acturing limited 3 functional block diagram figure 3. functional block diagram of AP3021 ordering information AP3021 - g1: green circuit type package m: soic-8 package temperature range part number marking id packing type soic-8 -40 to 85 c AP3021m-g1 3021m-g1 tube AP3021mtr-g1 3021m-g1 tape & reel bcd semiconductor's pb-free products, as designated with "g1" suffix in the part number, are rohs compliant and green. blank: tube tr: tape & reel
preliminary datasheet pwm controller AP3021 aug. 2012 rev. 1. 1 bcd semiconductor manuf acturing limited 4 absolute maximum ratings (note 1) parameter symbol value unit vdd pin voltage v dd -0.3 to 20 v en pin voltage v en -0.3 to v dd +0.3 v out pin voltage v out 20 v ovp pin voltage v ovp 7 v feedback pin voltage v fb -0.3 to 5.5 v thermal resistance ja 105 oc/w operating junction temperature t j 150 oc storage temperature t stg -65 to 150 oc lead temperature (soldering, 10sec) t lead 260 oc note 1: stresses greater than those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress ratings only, and functional op eration of the device at these or any other conditions beyond those indicated under ?recommended operating co nditions? is not implied. exposure to ?absolute maximum ratings? for extended periods may affect device reliability. recommended operating conditions parameter symbol min max unit input voltage v dd 4.0 18 v operating ambient temperature t a -40 85 oc
preliminary datasheet pwm controller AP3021 aug. 2012 rev. 1. 1 bcd semiconductor manuf acturing limited 5 electrical characteristics v dd =5v, t a =25oc, unless otherwise specified. parameters symbol conditions min typ max unit supply voltage (vdd pin) input voltage v dd 4.0 18 v quiescent current i q v fb =0.3v 5 ma shutdown current i shdn v en =0v 0.1 a under voltage lockout input uvlo threshold v uvlo v dd rising 3.8 v input uvlo hysteresis v hys 100 200 300 mv over voltage protection over voltage threshold 1.45 1.55 1.65 v over temperature protection thermal shutdown temperature t otsd 160 oc thermal shutdown hysteresis 20 oc enable (en pin) en pin threshold v en-off 0.3 v v en-on 2.6 v en pin dimming threshold v en-dim 0.4 0.5 v 2.4 2.6 v voltage reference (fb pin) feedback voltage v fb 0.194 0.2 0.206 v feedback bias current i fb 35 100 na line regulation v dd =4.5v to 8v t a =25oc 2 20 mv v dd =8v to 18v t a =25oc 4 40 mv output oscillator frequency f osc 247 330 412 khz maximum duty cycle d max 85 90 95 % out voltage (note2) v out i out =10ma v dd -1 v rising time t rise output pin load=1nf 65.5 ns falling time t fall 88.5 ns note 2: guaranteed by design.
preliminary datasheet pwm controller AP3021 aug. 2012 rev. 1. 1 bcd semiconductor manuf acturing limited 6 operation description 1. pwm operation the AP3021 uses a constant frequency, voltage mode control scheme to provide excellent line and load regulation. to drive led load, AP3021 can be connected as current regula tor (figure 5) or voltage regulator (figure 6), both topologies can realize led lighting and dimming. load regulation is less than 3% even if AP3021 is connected as voltage regulator. the maximum duty cycle of the pwm controller is limited to 93%. for more information please refer to the functional block diagram (figure 3). 2. enable control the en pin is used to turn on and off the controller. when en input voltage is lower than 0.3v, the controller turns off and the shutdown current can be limited under 0.1 a. when en input voltage goes higher than 2.6v, the controller turns on and the feedback voltage is set to 0.2v. when en voltage works at 0.5v to 2.4v, the ic will operate in dimming mode, more details please refer to section 4. the AP3021 has an internal 8015%k ? pull low resistor on the en pin, thus the device is normally in the off state or shutdown mode operation. 3. soft start control the AP3021 external comp ensation circuit can clamp the output waveform to soft start smoothly. 4. dc dimming control the dc dimming is to inject a constant dc voltage to en pin. the feedback voltage is indirectly adjusted when the en pin voltage is between 0.5v to 2.4v, which can be used as dimming control. application in figure 4 is designed so that a voltage signal of 0.5v to 2.4v varies the led current from minimum output current to maximum output current. comparing with all kinds of dimming control, this method features a best output voltage and leds current. figure 4. dimming control using a dc voltage signal in en pin 5. operation protection 5.1 over voltage protection the controller has an internal ovp circuit. the controller output voltage will boost too high when leds are disconnected from the circuit or fail open. the AP3021 will latch off the output if the ovp pin senses a voltage that is higher than 1.55v, and the power switching will be turned off. the latched off status can be reset by reducing the supply voltage to lower than 3.6v. 5.2 uvlo the AP3021 provides an under voltage lockout circuit to prevent it from undefined status when startup. the uvlo circuit turns the driver off when supply voltage drops below 3.6v. the uvlo circuit has 200mv hysteresis, which means the device starts up again when v dd rises to 3.8v. 5.3 otp the AP3021 monitors th e temperature of itself. if the temperature exceeds the threshold value (typically 160oc), the AP3021 shuts itself off. this is a no-latched protection. the device recovers once the temperature has decreased approximately 20oc. r1 AP3021 en fb dc voltage 0.5v to 2.4v 4 ?
preliminary datasheet pwm controller AP3021 aug. 2012 rev. 1. 1 bcd semiconductor manuf acturing limited 7 typical application figure 5. current regulator to drive leds
preliminary datasheet pwm controller AP3021 aug. 2012 rev. 1. 1 bcd semiconductor manuf acturing limited 8 typical application (continued) led1 led2 led3 led4 3 2 3 2 3 2 3 2 led3 led2 led1 led4 figure 6. voltage regulator to drive leds
preliminary datasheet pwm controller AP3021 aug. 2012 rev. 1. 1 bcd semiconductor manuf acturing limited 9 mechanical dimensions soic-8 unit: mm(inch) r0.150(0.006)
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