AT1361 AIMTRON | Alldatasheet

Document overview

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Technical content

Features

  • High efficiency (95%) possible
  • No Schottky Diode Required
  • 1A 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 AT1361 provides complete control for a DC/DC converter optimized for high- performance microprocessor applications. It is operated on current mode architecture for excellent line and load transient response. 1MHz operation frequency is allowing the use of small surface mount inductor and capacitor. The intern al synchronous switch increases efficiency and el iminates the need for an external Schottky diode. The AT1361 is a family of low-noise synchronous step-down DC/DC converters that is ideally suited for systems powered from a 1-cell Li-ion battery 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.

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw Pin Configuration

Ordering Information

Part number Package Marking AT1361X_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

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw Absolute Maximum Ratings:(TA=25°C) Rated Value Parameter Condition Min. Max. Unit Power Supply V oltage — -0.3 +6.0 V RUN,FB -0.3 VIN V Input Pin V oltage SW -0.3 VIN+0.3 V P-Channel Switch Source Current (DC) — - 1200 mA N-Channel Switch Sink Current (DC) — - 1200 mA Peak SW Sink and Source Current — - 1.5 A Thermal Resistance from Junction to Ambient θJA SOT-25 - 200 °C /W Operating temperature TA — -35 +85 °C Storage temperature — -55 +150 °C HBM 2 KV ESD Susceptibility *2 MM 200 V 1. Stresses beyond those listed under “Absolute Maximum Ra tings” may cause permanent damage to the device. These are stress ratings only, and func tional operation of the device at these or any 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. Device are ESD sensitive. Handling precaution r ecommended. The Human Body model is a 100pF capacitor discharged through a 1.5KΩ resistor into each pin. Recommended Operating Conditions (TA=+25°C) Values Parameter Symbol Min. Typ. Max. Unit Power supply voltage V IN 2.5 -- 5.5 Ƃ Operating temperature* T A -20 +25 +85 °C Operating junction temperature T J - - +150 °C *Using X5R or X7R input capacitors.

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw

Electrical Characteristics

(VIN =5V, TA=+25°C , unless otherwise noted. ) Values Parameter Symbol Condition Min. Typ. Max. Unit Input Supply Range V IN 2.5 -- 5.5 V Input Under-Voltage Lock Out threshold VUVLO IN Rising -- 2.3 -- V UVLO hysteresis -- 0.1 -- V Quiescent Current* IS FB=0.6V ,ILOAD=0A Active Mode -- 70 100 µA Current in standby mode I ST RUN=0V , VIN=5.5V -- 0.5 1 µA Feedback Voltage V FB 0.588 0.600 0.612 V Feedback Voltage line-regulation VFB-Line VIN =2.5V to 5.5V -- 0.1 0.5 %/V Feedback Variation with Temperature TA=-20°C to +85°C -- 0.5 1.0 % Feedback current I FB -- -- ±200 nA Peak Inductor Current* I PK VIN=5V ,VOUT=3.3V 1.2 1.8 -- A Maximum Output Current* IO VIN=5V±5%, VOUT=3.3V , L=4.7µH, TA=25°C 1 -- -- A fosc1 FB=0.6V 0.8 1.0 1.2 MHz Oscillator Frequency fosc2 FB=0V -- 200 -- KHz RDS(ON) of 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 I LSW RUN=0V,SW=0V or 5V,VIN=5V -- ±0.1 ±1 µA RUN High-Level Input Voltage VRUNÅH VIN =2.5V to 5.5V 1.5 -- -- V RUN Low-Level Input Voltage VRUNÅL VIN =2.5V to 5.5V -- -- 0.3 V RUN leakage Current I RUN -- ±0.1 ±1 µA L tVVIIII ONOUTIN OOPK × ×−+=∆+= 2

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw Typical characteristics : Quiescent Current vs. Input Voltage Input Voltage(V) Quisecent Current(uA) 7PVU Reference Voltage vs. Input Voltage Input Voltage(V) Reference Voltage(V) 7PVU Oscillator Frequency vs. Input Voltage Input Voltage(V) Oscillator Frequency(MHz) 7PVU -PBE Oscillator Frequency vs. Temperature 0.7 0.75 0.8 0.85 0.9 0.95 1.05 1.1 1.15 1.2 1.25 1.3 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 Temperature (Ċ) Oscillator Frequency (MHz Load=0.8A Load=1A 7*/ 7065 Vout Voltage vs. Temperature Temperature (Ċ) Vout Voltage(V) Vout Voltage vs. Temperature Temperature (Ċ) Vout Voltage(V)

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw Typical characteristics : Vout Voltage vs. Temperature Temperature (Ċ) Vout Voltage(V) Vout Voltage vs. Temperature Temperature (Ċ) Vout Voltage(V) 7*/ -PBE -PBE Efficiency VS. Load Current 100 10 100 1000 Load Current(mA) Efficiency(% 7*/ 7065 7*/ 7065 7*/ 7065 7*/ 7065 V)43 Efficiency VS. Load Current 100 10 100 1000 Load Current(mA) Efficiency(%) 7*/ 7065 7*/ 7065 7*/ 7065 V)43 Efficiency VS. Load Current 100 10 100 1000 Load Current(mA) Efficiency(% 7065 7065 7065 7065 V)43

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw Typical characteristics : Power ON/OFF CH1: VOUT C H 2 : VIN CH3:SW CH4:I IN VIN=5V,VOUT= 3 . 3 V , L o a d = 1 A , P o w e r O N VIN=5V,VOUT=3.3V,Load=1A,Power OFF EN pin ON/OFF CH1: VOUT C H 2 : E N C H 3 : S W C H 4 : IIN VIN=5V,VOUT= 3 . 3 V , L o a d = 1 A , E N T u r n - O N VIN=5V,VOUT=3.3V,Load=1A,EN Turn-OFF

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw Transient response CH2:VOUT CH4:IOUT VIN=5V,VOUT=3.3V,C2=100pF IOUT= 0 m A t o 1 A I OUT=50mA to 1A IOUT= 1 0 0 m A t o 1 A I OUT=200mA to1A Ripple noise ¸VIN=5V,VOUT= 3 . 3 V , L o a d = 0 A ¸VIN=5V,VOUT=3.3V,Load=1A

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw 1 0

Application Information

Short Circuit Protection Function The AT1361 has short circuit protection(see the Electrical Characteristics frequency item). When the output is shorted to ground, the fre quency of the oscillator is reduced to about 200KHz. This frequency foldback ensures that the inductor current has more time to decay. It will prevent the inductor current and internal P-MOSFET current runaway to damage the device. The frequency will retu rn to the normal values when the short circuit condition is removed and the feedback voltage reaches 0.6V . Capacitor Selection In continuous mode, the source current of th e 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 the AT1361. A load step at the output can induce ringing at the input VIN. This ringing can couple to th e output and be mistaken as loop instability. The oscillation can be improved by add the capacitance of the input capacitor. A typical value is 4.7~22 µF ceramic (X5R or X7R), POSCAP or Aluminum Polymer. These capacitors will provide good high frequenc y bypassing and their low ESR will reduce resistive losses for higher efficiency. The input capacitor RMS current varies with the input voltage and the output voltage. The equation for the maximum RMS current in the input capacitor is: The output capacitor depends on the suitabl e ripple voltage. Low ripple voltage corresponds to lower effective series resi stance (ESR). The output ripple voltage is determined by: The output capacitor RMS ripple current is given by: )1( IN O IN O OMAXRMS V V V VII −= OUT LOUT fCESRIV +∆≅∆ IN OUTINOUT RMS VfL VVVI ×× −×= )(

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw 1 1 When choosing the input and output ceramic capacitors, choose the X5R or X7R dielectric formulations. These dielectrics have the best temperature and voltage characteristics of all the ceramics for a given value and size. Inductor Selection The inductor is chosen based on the desired ripple current. Large value inductors lower ripple current and small value inductors result in higher ripple current. Always consider the losses associated with the DCR and its eff ect on the total converter efficiency when selecting an inductor. The inductor is sele cted to limit the ripple current to some predetermined value, typically 20~40% of th e full load current at the maximum input voltage. The formula of inductance value is as below: Adjustable Output Voltage The AT1361 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: *R1=150KΩ for stability consideration. )(4.0~2.0 MAXOUTL II ×=∆ ⎛ −∆×= IN OUT L OUT V V If VL 1 21(6.0 R RVVOUT +×= GND FB 0.6V=VOUT=5.5V

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw 1 2 The Dissipation The power loss is given by: Inductors Surface Mount Inductance(µH) Manufacturer/Part No. Manufacturer Website 4.7 Sumida CDRH4D28-4R7 www.sumida.com 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 LOSSJAAMAXJ PTT ×+= θ)( QINfrOD frOINNONDSOPONDSOLOSS IVfttIV fttIVDRIDRIP s s)( )(2 )(2 1)1(

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw 1 3 PC Board Layout 1. The most critical aspect of the layout is the placement of the input capacitor C1. It must be placed as close as possible to the AT1361 to reduce the input 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 inductance it will have. The length of traces in series with the capacitors increases its ESR and ESL and reduces their effectiveness at high frequency. 3. The FB pin should connect to feedback resistors 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 may effectively reduce the occurrence of loop.

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw 1 4 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 -

1MHz,1A 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 / 1 1 / 2 0 0 8 R E V : 1 . 0 E m a i l : service@aimtron.com.tw 1 5 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 -Ramp-up Rate 3°C/second max. Time maintained above: -Temperature (TL) -Time (t L) 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 actual 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 25 °C to Peak Temperature 6 minutes max. 8 minutes max. *All temperatures refer to topside of the package, measured on the package body surface.