LR KHz, 3A PWM Buck DC/DC Converter

Transcription

1 ESHN RIO NY, T. 15KHz, 3 PWM Buck C/C Converter escription The is Monolithic IC that design for a stepdown C/C Converter, and own the ability of driving a 3 load without additional transistor component. The output version included 3.3, 5, 12 and an adjustable type. It operates at a switching frequency of 15KHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Other features include a guaranteed ±4% tolerance on output voltage under specified input voltage and output load conditions, and ±15% on the oscillator frequency. Regarding protected function, thermal shutdown is to prevent over temperature operating from damage, and current limit is against over current operating of the output switch. Features 3.3, 5, 12 and adjustable djustable version output voltage range: ±4% max over line and load conditions 15KHz ±15% fixed switching frequency TT shutdown capability Operating voltage can be up to 4 Output load current: 3 TO225 and TO2635 packages ow power standby mode Thermalshuntdown and currentlimit protection High efficiency Builtin switching a transistor on chip, requires only 4 external components pplications Simple Highefficiency stepdown regulator Positive to negative converter Oncard switching regulators Connection iagrams TO225 Package TO2635 Package Series TO225 Pins 1,3,5 TO2635 Side iew Pins 2,4 Side iew Top iew 5 On/Off 4 Feed Back 3 Ground 2 Output 1 IN Top iew 5 On/Off 4 Feed Back 3 Ground 2 Output 1 IN Metal Tab GN Metal Tab GN 1/7

2 Pin Connections S ESHN RIO NY, T. IN Current Source Bias Reference 2.5 Regulator Start Up 2m 22m R FB R2 R1=2.5K MP 15KHz OSC. Current imit river Thermal imit 3 Switch Output GN bsolute Maxium Rating (Note1) Parameter Symbol alue Unit Supply oltage CC 4 On/Off Pin Input oltage S.3~25 Feedback Pin oltage FB.3~25 Output oltage to Ground OUT 1 Power issipation P Internally imited W Operating Temperature T opr 4~125 Storage Temperature T stg 65~15 Operating oltage OP 4.5~4 o C o C Electrical Characteristics (Continued) Specifications with boldface type apply over for full operating temperature range, the other type are for T J=25 o (Note 2) C Part No. Parameter Symbol Conditions Min J Output oltage OUT 4.75 IN 4,.2 I O Typ. (Note3) 3.3 Max. (Note4) Efficiency η IN =12, I O =3 73 % Output oltage OUT 7 IN 4,.2 I O Efficiency η IN =12, I O =3 8 % Output oltage OUT 15 IN 4,.2 I O Efficiency η IN =25, I O =3 9 % Output oltage OUT 4.5 IN 4,.2 I O 3 OUT programmed for Efficiency η IN =12, OUT =3, I O =3 73 % Unit 2/7

3 ll Output oltage ersions Electrical Characteristics Specifications with boldface type apply over for full operating temperature range, the other type are for T J=25 o C (Unless otherwise specified, IN=12 for the 3.3, 5, and adjustable version and IN=24 for the 12 version, I O=5m) evice Parameters Parameter Symbol Test Condition Min. Typ. Max. Unit Feedback Bias Current I b djustable ersion Only, FB =1.3 1 Oscillator Frequency f O (Note 5) Saturation oltage ST I OUT =3 (Note 6,7) 1.3 Max. uty Cycle (ON) Min. uty Cycle (OFF) C (Note 7) (Note 8) Current imit I C Peak Current (Note 6,7) n KHz % Output eakage Current I Output= (Note 6,8) 5 u Quiescent Current I Q (Note 8) Standby Quiescent Current I STBY ON/OFF pin=5 (Note 9) 15 Thermal Resistance ON/OFF Control ON/OFF Pin ogic Input Threshold oltage ON/OFF Pin Input Current θ JC θ J (Note 1) ESHN RIO NY, T m 25 3 TO225 Junction to 2.5 TO2635 Case 3.5 TO225 Junction to 28 TO2635 ambient 23 IH ow (Regulator ON) I High (Regulator OFF) 2. I IH OGIC =2.5 (Regulator OFF) 5 15 I I OGIC =.5 (Regulator ON).2 5 Note 1: bsolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. Note 2: External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator system performance. Note 3: Typical numbers are at 25 o C and represent the most likely norm. Note 4: ll limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). ll room temperature limits are 1% production tested. ll limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. ll limits are used to calculate verage Outgoing Quality evel (OQ). Note 5: The switching frequency is reduced when the second stage current limit is activated. Note 6: No diode, inductor or capacitor connected to output pin. Note 7: Feedback pin removed from output and connected to to force the output transistor switch ON. Note 8: Feedback pin removed from output and connected to 12 for the 3.3, 5, J. version, and 15 for the 12 version, to force the output transistor switch OFF. Note 9: IN =4. Note 1: Junction to ambient thermal resistance. (With copper area of approximately 3in 2 ) u o C/W o C/W u 3/7

4 ESHN RIO NY, T. Characteristics Curve 1.5 Normalized Output oltage 16 Shutdown Quiescent Current Output oltage Change (%) IN=12 I O =2m Current (u) ON/ OFF=5 T J=25 o C Junction Temperature ( o C) Supply oltage () Switch Current imit () Switch Current imit IN =12 OUT=5 Saturation oltage () IN =12 T J =25 o C Switch Saturation oltage Junction Temperature ( o C) Switch Current () 12 On/Off Pin Current (Sinking) 1 Current (u) 8 6 IN=4 T J =25 o C On/Off Pin oltage () 4/7

5 Typical pplication Circuit ESHN RIO NY, T. Fig.1 Fixed Type Circuit 4 Feedback Unregulated C Input 1 Input C1 68uF 2596 Fix Output 3 GN 2 Output 5 ON/OFF 1 1N uH C2 22uF O Fig.2 djustable Output oltage ersions R2 1K 4 R1 Unregulated C Input 1 Input C1 68uF 2596 djustable Output Output 1 1N uH C2 22uF O 5/7

6 TO2635 imension ESHN RIO NY, T. B C G E a1 F H I J K Marking: Pb Free Mark. " PbFree: " Normal: None ate Code U Product Series J,3.3,5., Control Code Note: Green label is used for pbfree packing Pin Style: 1.in 2.Output 3.Ground 4.Feed Back 5.On/Off Material: ead solder plating: Sn6/Pb4 (Normal), Sn/3.g/.5Cu or PureTin (Pbfree) Mold Compound: Epoxy resin family, flammability solid burning class: U94 IM Min. Max B #7.1 C *1.7 E F *1.27 G H.5.25 I J K #7. #4.48 a1 O 7 O #: REF, *: Typical, Unit: mm 5ead TO263 Plastic Package BMI Package Code: U TO225 imension C S B r2 G I r1 H E F K a1 r3 P O J R a1 M a1 N r3 r3 Q Marking: Pb Free Mark PbFree: ". " Normal: ate Code E Product Series J,3.3,5.,12 Control Code Note: Green label is used for pbfree packing Pin Style: 1.in 2.Output 3.Ground 4.Feed Back 5.On/Off Material: ead solder plating: Sn6/Pb4 (Normal), Sn/3.g/.5Cu or PureTin (Pbfree) Mold Compound: Epoxy resin family, flammability solid burning class: U94 5ead TO22 Plastic Package BMI Package Code: E IM Min. Max B C E F G H.7.9 I J K M N O P Q R S r r r a1 4.5 o 5.5 o *: Typical, Unit: mm 6/7

7 ESHN RIO NY, T. Soldering Methods for BMI s Products 1. Storage environment: Temperature=1 o C~35 o C Humidity=65%±15% 2. Reflow soldering of surfacemount devices Figure 1: Temperature profile TP Rampup tp Critical Zone T to TP T Tsmax t Temperature Tsmin ts Preheat Rampdown 25 t 25 o C to Peak Time Profile Feature SnPb Eutectic ssembly PbFree ssembly verage rampup rate (T to T P) <3 o C/sec <3 o C/sec Preheat Temperature Min (Ts min) Temperature Max (Ts max) Time (min to max) (ts) Tsmax to T 1 o C 15 o C 6~12 sec 15 o C 2 o C 6~18 sec Rampup Rate <3 o C/sec <3 o C/sec Time maintained above: Temperature (T ) Time (t ) 183 o C 6~15 sec 217 o C 6~15 sec Peak Temperature (T P) 24 o C /5 o C 26 o C /5 o C Time within 5 o C of actual Peak Temperature (t P) 1~3 sec 2~4 sec Rampdown Rate <6 o C/sec <6 o C/sec Time 25 o C to Peak Temperature <6 minutes <8 minutes 3. Flow (wave) soldering (solder dipping) Products Peak temperature ipping time Pb devices. 245 o C ±5 o C 5sec ±1sec PbFree devices. 26 o C /5 o C 5sec ±1sec 7/7