AT1366B AIMTRON | Alldatasheet

Document overview

  • Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
  • PDF pages: 14

Technical content

Features

  • High efficiency (95%) possible
  • No Schottky Diode Required
  • 800mA Output Current at 5V input 3.3V output
  • Oscillation frequency 1.0MHz
  • Built-in ON/OFF Function
  • Built-in Short Circuit Protection
  • Low Dropout Operation: 100% Duty Cycle
  • Stand-by current max. 1µA
  • Input voltage: 2.5V ~5.5V

Applications

  • Power Supply for portable devices General Description The AT1366B provides co mplete cont rol fo r a DC/DC converter optimized for h igh-performance microprocessor applications . It is ope rated on current m ode architecture for excellent line and load transient response. 1MHz operation frequency is allowing the use of small surface mount inductor and capacitor. The i nternal sy nchronous swi tch increases efficiency and eliminates the need for an external Schot tky diode. The A T1366 is a family of l ow-noise sy nchronous st ep-down DC/DC converters t hat is id eally su ited for systems powered from a 1 -cell Li -ion bat tery or from a 3-cell to 4-cell NiCd, NiMH, or alkaline battery. It can also be used to USB-Based power system. Block Diagram Aimtron reserves the right without notice to change this circuitry and specifications.

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw Pin Configuration

Ordering Information

P art number Package Marking AT1366BX SOT-25 ····· : Date Code AT1366BX_GRE SOT-25,Green ····· : Date Code with one bottom line *For more marking information, contact our sales representative directly Pin Description Symbol Pin No. Descript RUN 1 ON/OFF Control GND 2 Power ground SW 3 Switch Node Connection to Inductor VIN 4 Power Supply FB 5 Output Feedback

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw Absolute Maximum Ratings Rated Value Parameter Condition Min. Max. Unit Power Supply Voltage — -0.3 +6.0 V RUN,FB -0.3 VIN V Input Pin Voltage SW -0.3 VIN+0.3 V P-Channel Switch Source Current (DC) — - 1000 mA N-Channel S witch Si nk C urrent (DC) — - 1000 mA Peak SW Sink and Source Current — - 1.5 A Thermal Resistance from Junction to Ambient θJA SOT-25 - 200 0C/W Operating temperature TA — -35 +85 0C Storage temperature — -55 +150 0C HBM 2 KV ESD Susceptibility *2 MM 200 V 1. Stresses beyond those listed unde r “Absolute Maximum Ratings” may cause permanent damage to the device. Th ese are s tress ratings on ly, and functional operation of th e d evice at these or an y other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2. Dev ice ar e ESD sensitive. Handling pr ecaution r ecommended. The Hu man Body mo del is a 100pF capacitor discharged through a 1.5KΩ resistor into each pin. Recommended Operating Conditions (Ta=+250C) Values Parameter Symbol Min. Typ. Max. Unit Power supply voltage VIN 2.5 -- 5.5 Ƃ Operating temperature* TA -20 +25 +85 °C Operating junction temperature TJ - - +150 °C *Using X5R or X7R input capacitors.

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw

Electrical Characteristics

(VIN = 3.6V,Ta =+25Ċ , unless otherwise noted. ) Values Parameter Symbol Condition Min. Typ. Max. Unit Input Supply Range VIN 2.5 -- 5.5 V Quiescent Current* IS FB=0.6V, Iload=0A Active Mode -- 300 -- µA Current in standby mode IST RUN=0V, VIN=5.5V -- 0.5 1 µA Feedback Voltage VFB Ta =-20Ċ to +85Ċ 0.588 0.600 0.612 V Feedback Voltage line-regulation VFB-Line VCC=2.5V to 5.5V -- 0.1 0.5 % Feedback Variation with Temperature Ta =-20Ċ to +85Ċ -- 0.5 1.0 % Feedback current IFB -- -- ±200 nA Peak Inductor Current* IPK VIN=5V,VOUT=3.3V 1.10 1.25 1.50 A Maximum Output Current* IO VIN=5V±5%, VOUT=3.3V, L=4.7µH - - 800 mA fosc1 FB=0.6V 0.8 1.0 1.2 MHz Oscillator Frequency fosc2 FB=0V -- 200 -- KHz RDS(ON) o f P-Channel MOSFET RPFET ISW=600mA -- 0.4 0.5 Ω RDS(ON) of N-Channel MOSFET RNFET ISW=-600mA -- 0.35 0.45 Ω SW Leakage Current ILSW RUN=0V,SW=0V or 5V,VIN=5V -- ±0.1 ±1 µA RUN Threshold VRUN 0.3 1.0 1.5 V RUN leakage Current IRUN -- ±0.1 ±1 µA L tVVIIII ONOUTIN OOPK × ×−+=∆+= 2

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw Typical characteristics : (refer to Figure 2)

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw Typical characteristics : Start-Up from Shutdown(VIN=3.6V) CH1:RUN C H2:VOUT C H4:IL

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw Typical characteristics (Continuted) VIN=5V,VOUT=3.3V CH2:VOUT C H4:IOUT ILOAD=0mA to 600mA ILOAD= 50mA to 600mA ILOAD= 100mA to 600mA ILOAD= 200mA to 600mA ILOAD= 50mA to 800mA ILOAD= 200mA to 800mA

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw

Application Information

Short Circuit Protection Function The AT1366B has short circuit protection(see the Electrical Characteristics frequency item). When the output is shorted to ground, th e frequency of the oscillator is reduced to about 200KHz. This frequency foldback ensures that the inductor current has m ore time to decay . It will p revent the inducto r cu rrent and in ternal P-MOS FET current runaway to dam age the device. The f requency will r eturn to the norm al values when the short circuit condition is removed and the feedback voltage reaches 0.6V. Capacitor Selection In continuous m ode, the source current of the top MOSFET is square wave of duty cycle. The Primary function of the input capacitor is to provide a low impedance loop for the edges of pulsed current drawn by th e AT1366B. A load step at the output can induce ringing at the input VIN. This ringing can couple to the output and be mistaken as loop instability. The oscillation can be improved by add the capacitance of the input capacitor. A typical value is 4.7~22µF ceramic (X5R or X7R), POSCAP or Aluminum Polymer. These capacitors will provide good high frequency bypassing and their low ESR will r educe resistive losses f or high er e fficiency. The inpu t ca pacitor RMS current varies with the input voltage a nd the output voltage. The equation for the maximum RMS current in the input capacitor is: )1( IN O IN O OMAXRMS V V V VII −= The output capacitor depends on the suit able ripple voltage. Low ripple voltage corresponds to lower ef fective series resist ance (ESR). The output ripple voltage is determined by: OUT LOUT fCESRIV +∆≅∆ The output capacitor RMS ripple current is given by:

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw IN OUTINOUT RMS VfL VVVI ×× −×= )( When choosing the input and output ceram ic capacitors, choose the X5R or X7 R dielectric form ulations. These dielectrics have the best tem perature and voltage characteristics of all the ceramics for a given value and size. Inductor Selection The inductor is chosen based on the desire d ripple current. Lar ge value inductors lower ripple current and s mall value inductors result in higher ripple current. Always consider the losses associated with the DCR and its ef fect on the total converter efficiency when selecting an indu ctor. Th e in ductor is se lected to lim it the ripp le current to some predetermined value, typically 20~40% of the full load current at the maximum input voltage. The formula of inductance value is as below: )(4.0~2.0 MAXOUTL II ×=∆ ⎛ −∆×= IN OUT L OUT V V If VL 1 Adjustable Output Voltage The AT1366B appears a 0.6V reference voltage at FB pin. The output voltage is set by a resistive divider which is according to the following formula: 21(6.0 R RVVOUT +×= *R1=150KΩ for stability consideration. 1 0

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw The Dissipation The power loss is given by: INsfrOINNONDSOPONDSOLOSS VIfttIVDRIDRIP ×+×+××+−××+××= −− s)( 2 )()1( LOSSJAAMAXJ PTT ×+= θ)( Inductors Surface Mount Inductance(µH) Manufacturer/Part No. Manufacturer Website

3.3 Sumida CDRH4D28-3R3

4.7 Sumida CDRH5D18-4R7

www.sumida.com 3.3 Mitsumi C3-K1.8L-3R3 Mitsumi C4-K1.8L-3R3 www.mitsumi.co.jp

3.3 ABC SH40283R3YSB

4.7 ABC SH40284R7YSB

www.atec-group.com Capacitors Surface Mount Capacitance(µF) Manufacturer/Part No. Manufacturer Website 22 TDK C3216X5R0J226M www.tdk.com 47 TDK C3225X5R0J46M www.tdk.com 10 GRM42-6X5R 106K6.3 www.murata.com 4.7 TAIYO JMK212BJ475MG www.t-yuden.com 1 1

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw PC Board Layout 1. The most critical aspect of the layou t is the placement of the input capacitor C1. It must be placed as close as possible to the A T1366B to reduce the in put ripple voltage. 2. Power loops on the input and output of the converter should be laid out with the shortest and widest traces possible. The longer and na rrower the trace, the higher resistance and inductan ce it will h ave. The length of traces in series with the capacitors increases its ESR and ESL and reduces th eir ef fectiveness at high frequency. 3. The FB pin should connect to feedback re sistors directly. And the route should be away from the noise source, such as inductor of SW line. 4. Grounding all components at the same point m ay effectively reduce the occurrence of loop. 1 2

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw Package Outline :SOT-25 INCHES MILLIMETERS SYMBOL MIN MAX MIN MAX NOTES A 0.035 0.057 0.90 1.45 - A1 0.000 0.006 0.00 0.15 - A2 0.035 0.051 0.90 1.30 - b 0.010 0.020 0.25 0.50 - C 0.003 0.008 0.08 0.20 - D 0.110 0.122 2.80 3.10 - E 0.102 0.118 2.60 3.00 - E1 0.059 0.069 1.50 1.75 - L 0.014 0.022 0.35 0.55 e 0.037ref 0.95ref e1 0.075ref 1.90ref r 00 100 00 100 - 1 3

Preliminary Product Information 1MHz,800mA Synchronous Buck Converter 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW : http://www.aimtron.com.tw 1/18/2006 R EV:1.2 E mail:service@aimtron.com.tw Reflow Profiles Sn-Pb Eutectic Assembly Pb-Free Assembly Profile Feature Large Body Pkg. thickness ≥2.5mm or Pkg. volume ≥350mm3 Small Body Pkg. thickness <2.5mm or Pkg. volume <350mm3 Large Body Pkg. thickness ≥2.5mm or Pkg. volume ≥350mm3 Small Body Pkg. thickness ≥2.5mm or Pkg. volume ≥350mm3 Average ramp-up rate (TL to TP) 3°C/second max. 3°C/second max. Preheat -Temperature Min(Tsmin) -Temperature Max (Tsmax) -Time (min to max)(ts) 100°C 150°C 60-120 seconds 150°C 200°C 60-180 seconds Tsmax to TL -Ram p-up Rate 3°C/second max. Time maintained above: -Temperature (TL) -T ime (tL) 183°C 60-150 seconds 217°C 60-150 seconds Peak Temperature(TP) 225+0/-5°C 240+0/-5°C 245+0/-5°C 250+0/-5°C Time within 5°C of a ctual Peak Temperature (tP) 10-30 seconds 10-30 seconds 10-30 seconds 20-40 seconds Ramp-down Rate 6°C/second max. 3°C/second max. Time 2 5°C to Peak Temperature 6 minutes max. 8 minutes max. *All temperatures refer to topside of the package, measured on the package body surface. 1 4