AT1309 AIMTRON | Alldatasheet

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Technical content

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Feature

  • Operating Voltage:2.5V to 6.0V.
  • High Operating Frequency: 1.4MHz
  • High Output Voltage: Up to 28V
  • Shutdown Current <1µA
  • Digital Dimming Control.
  • Built-in Cycle-by Cycle Current-Limiting.
  • Built-in Soft-Start Function.
  • ±1.5% 1.23V Reference Voltage
  • Tiny SOT-25 Package A pplication
  • STN/OLED Bias
  • Personal Digital Assistants(PDAs)
  • DSC

Description

The AT1309 step-up converter is designed for small or medium size LCD panel of high bias voltage with a constant c urrent to provide PDAs, and other hand-held de vices. It features a fast 1. 4 MHz current-mode PWM con trol with a bu ilt-in 0.3Ω N-MOS t hat allows for sm aller capacitor a nd inductor. Fa ult condition protection uses cycle-by -cycle cur rent l imiting t o s ense m aximum i nductor current and t hermal protection. Al so i ncluded soft-start eliminates inrush current during start-up. The AT1309 is available in 5-pin SOT-25 packages. Block Diagram Aimtron reserves the right without notice to change this circuitry and specifications. 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Pin Configuration

Ordering Information

Part number Package Marking AT1309X SOT-25 Date Code AT1309X_GRE SOT-25, Green ,Date Code with one bottom line : Date Code *For more marking information, contact our sales representative directly Pin Description Pin N0. Symbol I / O Description 1 LX I Step-up Regulator N-MOS Drain. Place output diode and inductor.

2 GND P Ground

3 FB I Step-Up Regulator Feedback Input. Connect a sense resistor from FB to ground.

4 EN I

Enable and Dimming Control Input. LED brightness and IC shutdown are controlled by the voltage on EN. Driving low for longer than 4ms to shutdown the IC. 5 VIN P Power supply. 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Absolute Maximum Ratings*1 Parameter Rated Value Unit VIN voltage -0.3 to +6.5 V LX voltage -0.3 to +30 V EN , FB to GND -0.3 to +6.5 V Switch Current (ILX) 1.8 A Continuous power dissipation (SOT-25 Ta=+25OC) 0.25 W Operating Junction Temperature Range -30 to 85 Ċ Lead Temperature (Soldering 5 sec) 260 Ċ Storage Temperature -65 to 125 Ċ Package Thermal Resistance (ƨJA) 250 Ċ/W 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 Operation Conditions Values Parameter Symbol Min. Typ. Max. Unit Power supply voltage VIN 2.5 ķ 6.0 V Operating temperature Top -20 +25 +85 Ċ 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter

Electrical Characteristics

(VIN=2.5V, Ta=+25Ċ, unless otherwise noted) Parameter Symbol Test Condition Min. Typ. Max. Units Operating V IN Range VIN VIN input Voltage 2.5 - 6.0 V Under Voltage Thershold UVLO VIN falling, 100mV hysteresis 2.1 2.2 2.3 V Switch- Off Input Current IIN1 No Switching - 100 120 µA Shutdown Current IIN3 EN=0V - - 1 µA Feedback Reference VFB 1.212 1.230 1.248 V FB Input Bias Current IFB VFB =0.2V - - 1 µA Output Voltage Line Regulation 2.5V< VIN <6.0V - 0.1 - % Switching Frequency fOSC - 1.4 - MHz Maximum Duty DMAX - 90 - % Soft-Start charging time tSS - 0.5 - ms Switching Current Limit ILX VIN=3.0V,duty cycle=80% - 1.0 - A LX ON Resistance RLX ILX =350mA - 0.3 - Ƹ LX Leakage Current ILeakage VLX =28V, EN=0V - - 1 µA EN Input Current IEN EN=5V - - 8 µA VIH 0.1V hysteresis 2.0 - - V EN Input Level VIL - - 0.8 V EN low Shutdown Delay - 4 - ms Thermal Shutdown - 120 - Ċ 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Typical Characteristics Efficiency vs. Load current Load current Efficiency (%) 7*/ 7*/ 7*/ Efficiency vs. Load current Load current Efficiency (%) Efficiency vs. VIN VIN(V) Efficiency (%) *065 *065 *065 Vo=15V L=10uHVo=15V L=10uH Quiescent current vs. VIN VIN (V) Quiescent current (uA) Vo=15V Vin=3.0V TA=25OC 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Load Transient Response VIN=3.0V, Vout=15V, L=10uH, Iout=10mA to 100mA Ch1:Vout (AC mode), Ch4:Iout, Time:0.2ms/div Line Transient Response VIN=3.0V to 6.0V, Vout=15V, L=10uH, Iout=100mA Ch1:VIN, Ch2:Vout (AC mode), Ch3:IIN, Time:0.5s/div 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Start up Waveform with Load VIN=3.0V, Vout=15V, L=10uH, Iout=100mA Ch1:Vout, Ch2:EN, Ch3:IIN, Time:5ms/div LX Switching Waveform VIN=3.0V, Vout=15V, L=10uH Ch1:LX, Ch3:ILX, Time:0.5us/div 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Application Circuit LX GND FB 20pF VIN MBR0530 4.7uH 4u7F VIN 2.5V to 5.0V AT1309 EN 180K 16K 1uF 15V/4mA MBR0530 MBR0530 MBR0530 1uF -15V/4mA 1uF 1uF Fig3. ±15V Dual Output Converter LX GND FB VIN SS24 10uH 10uF VIN 3.0V to 5.0V AT1309 EN 180K 16K 10uF 15V/100mA 20pF Fig4. 15V Boost 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Function Description The AT1309 is designed primarily for use in STN/OLED bias applications. The output voltage of the step-up converter can be set from Vin to 26V with external resistive voltage divider. The boost converter opera tes in current-m ode PWM and a constant frequency of 1.0 MHz. Depending on duty cycl e of each switching cycle can regulate output voltage. On the rising edge of the in ternal clock, the control and driver logic block sets internal flip-flop when t he output voltage is too low , which turns on the N-MOS. The external inductor current ramps up linearly, storing energy in a magnetic filed. Once peak current of inductor over trans-conductance output level, the N-MOS turns off, the f lip-flop resets, and e xternal schottky diode turns on . This forces the current through the inductor to ram p back down, transferring the energy stored in the magnetic field to the output capacitor and load. To reduce external component amount, the device will be built-in internal loop compensation. Enable Control Digital logic of EN pr ovides an electri cal ON/OFF cont rol of the power supply . Connecting this pin to g round or to any volta ge less th an 0.7V will completely tu rn OFF the regulator. In this state, current drain from the input s upply is less than 1 µA, the internal reference, error amplifier, comparators, and biasing circuitry turn off . EN works as a simple on/off control. Drive EN high to enable the device, or drive E N low for shutdown. Soft-Start Soft-start allows a gradu al increase of the intern al current-limit level f or the s tep-up converter during power -up to reduce input su rge currents. As the internal current source charges the internal soft-start capacitor, the peak N-MOS current is lim ited by the voltage on the capacitor. Cycle-by-Cycle Over-Current Protection The A T1309 provides cycle-by-cycle over -current protection. Current lim it is accomplished using a separate dedicated comparator. The cycle-by-cycle current limit abbreviates the on-time of the N-MOS in ev ent that the current of flowing N-MOS is greater than the current limit value. The current-limit feature protection against a hard short or over-current fault at the output. Thermal-Overload Protection Thermal-overload protection lim its total pow er dissipation in the A T1309. When the junction temperature exceeds Tj=130 , a th ermal sensor activates the therm al Ċ protection, which shuts down the IC, allowing the IC to cool. Once the device cools down by 10 , IC will autom atically re cover norm al operation. For continuou s Ċ operation , do not exceed the absolute maximum junction-tem perature rating of Tj=120 Ċ. 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Power dissipation consideration The AT1309 maximum power dissipation depends on the therm al resistance of the IC package and circuit board, the tem perature difference between the die junction and ambient air, and the rate of any airflow . The power dissipation in the device depends on the operating conditions of the regulato r. In continuou s condition, the step-up converter power dissipated internally across the internal N-MOS can be approxim ated by : DRLf DV V VIP ONDS OSC in in OO boost ××× ×+×= )( 22 ])(12 1)[( where IO : It is the load current. fOSC : It is a switching frequency. 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter

Application Information

External components of boost converter can be designed by performing si mple calculations. Boost inductor Inductor selection depends on input voltage, output voltage, maximum output current, switching frequency and availability of i nductor values. The following boost circui t equations are useful in choosing the induc tor values based on the application. They allow the trading of peak current and induc tor value while allowi ng for consideration of component availability and cost. The peak inductor current is given by: D II III O LAVG L LAVGLpeak ∆+= where: ¶IL is the inductor peak-to-peak current ripple and is decided by: OSC in L f D L VI ×=∆ D is the MOSFET turn on ratio and is decided by: O inO V VVD −= fOSC is the switching frequency. The inductor should be chosen to be able to handle this current and inductor saturation current rating should be greater than IPEAK. Diode selection The output diode has average current of I O, and peak curren t the sam e as the inductor’s peak current and a voltage ra ting at least 1.5 tim es the output voltage. Schottky diode is recommended and it should be able to handle those current. Output Capacitor The AT1308 is specially compensated to be stable with capacitors which have a worst- case m inimum value of 1uF at the particular V OUT being s et. Output ripple voltage requirements also determine the minimum value and type of capac itors. Output ripple voltage consists of two com ponents the voltage drop caused by the switching current through the ESR of the output capacitor an d the char ging and dischar ging of the output capacitor: OSCOUT O O inO LPEAKRIPPLE fC I V VVESRIV ××−+×= For low ESR ceram ic c apacitors, the output ripple is dom inated by the char ging or discharging of the output capacitor. 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Impacting frequency stability of the overall control loop, Ceram ic capacitors are preferred on the output capacitance, but tant alum capacitor may also suffice. If it use tantalum capacitor on the output term inal, th at in addition the cap acitance parallel with feedback resisto r network is n ecessary. These frequency response ef fects together with the internal frequency co mpensation circuitry of A T1308 m odify the gain and phase shift of the closed loop system. PCB layout guidelines Careful printed circuit layout is extrem ely im portant to avoid causing parasitical capacitance and line inductance. The following layout guidelines are recommended to achieve optimum performance. ‧Please the boost converter diode and induc tor close to the LX pin and no via. Keep traces short, direct, and wide. ‧Please ceramic bypass capacitors near the input/output pin. ‧Locate all feedback sense resistors as close to the feedback pins as possible. ‧The ground connections of VIN and VOUT should be as close together as possible. 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter Small Outline SOT-25 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw

Preliminary Product Information M icro-Power S tep u p D C-DC C onverter 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. 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 3/2/2006 REV :1.1 Email: service@aimtron.com.tw