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AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter Feature
*Operating Voltage:2.5V to 6.0V. *High Operating Frequency: 1.4MHz *High Output Voltage: Up to 28V *Shutdown Current <1A *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
Description
The AT1309 step-up converter is designed for small or medium size LCD panel of high bias voltage with a constant current to provide PDAs, and other hand-held devices. It features a fast 1.4 MHz current-mode PWM control with a built-in 0.3 N-MOS that allows for smaller capacitor and inductor. Fault condition protection uses cycle-by -cycle current limiting to sense maximum inductor current and thermal protection. Also included soft-start eliminates inrush current during start-up. The AT1309 is available in 5-pin SOT-25 packages.
Application
* STN/OLED Bias * Personal Digital Assistants(PDAs) * DSC
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 1
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter Pin Configuration
Ordering Information
Part number AT1309X AT1309X_GRE : Date Code *For more marking information, contact our sales representative directly Package SOT-25 SOT-25, Green Marking Date Code ,Date Code with one bottom line
Pin Description
Pin N0. 1 2 3 4 5 Symbol LX GND FB EN VIN I/O I P I I P Description Step-up Regulator N-MOS Drain. Place output diode and inductor. Ground Step-Up Regulator Feedback Input. Connect a sense resistor from FB to ground. 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. Power supply.
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AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter Absolute Maximum Ratings*1
Parameter VIN voltage LX voltage EN , FB to GND Switch Current (ILX) Continuous power dissipation (SOT-25 Ta=+25 C) Operating Junction Temperature Range Lead Temperature (Soldering 5 sec) Storage Temperature Package Thermal Resistance ( ESD Susceptibility*2
JA) O
Rated Value -0.3 to +6.5 -0.3 to +30 -0.3 to +6.5 1.8 0.25 -30 to 85 260 -65 to 125 250 HBM MM 2 200
Unit V V V A W
/W KV V
1. Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional 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 recommended. The Human Body model is a 100pF capacitor discharged through a 1.5K resistor into each pin.
Recommended Operation Conditions
Parameter Power supply voltage Operating temperature Symbol Min. VIN Top 2.5 -20 +25 Values Typ. Unit V
Max. 6.0 +85
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AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter Electrical Characteristics
(VIN=2.5V, Ta=+25 , unless otherwise noted)
Parameter Operating V IN Range Under Voltage Thershold Switch- Off Input Current Shutdown Current Feedback Reference FB Input Bias Current Output Voltage Line Regulation Switching Frequency Maximum Duty Soft-Start charging time Switching Current Limit LX ON Resistance LX Leakage Current EN Input Current EN Input Level EN low Shutdown Delay Thermal Shutdown
Symbol VIN UVLO IIN1 IIN3 VFB IFB
Test Condition VIN input Voltage VIN falling, 100mV hysteresis No Switching EN=0V
Min. 2.5 2.1 -
Typ. Max. Units 2.2 100 6.0 2.3 120 1 V V A A V A % MHz % ms A
1.212 1.230 1.248 VFB =0.2V 2.5V< VIN <6.0V VIN=3.0V,duty cycle=80% ILX =350mA VLX =28V, EN=0V EN=5V 0.1V hysteresis 2.0 0.1 1.4 90 0.5 1.0 0.3 4 120 1 1 8 0.8 -
fOSC DMAX tSS ILX RLX ILeakage IEN VIH VIL
A A V V ms
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 4
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter Typical Characteristics
Efficiency vs. Load current
Efficiency vs. VIN
Vo=15V L=10uH
Vo=15V L=10uH
Load current
Efficiency (%)
Efficiency (%)
VIN(V)
Efficiency vs. Load current
Quiescent current vs. VIN
Vo=15V Vin=3.0V TA=25OC
Quiescent current (uA)
Load current
Efficiency (%)
VIN (V)
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 5
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter
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 6
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter
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 7
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter Application Circuit
MBR0530 -15V/4mA 1uF 1uF 4.7uH VIN 2.5V to 5.0V MBR0530 4u7F 1uF 15V/4mA MBR0530
VIN
LX
MBR0530 20pF 1uF
AT1309
EN FB
180K
16K
GND
Fig3. 15V Dual Output Converter
10uH VIN 3.0V to 5.0V SS24 10uF
15V/100mA
VIN
LX
20pF
10uF
AT1309
EN FB
180K
16K
GND
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 8
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter 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 operates in current-mode PWM and a constant frequency of 1.0 MHz. Depending on duty cycle of each switching cycle can regulate output voltage. On the rising edge of the internal clock, the control and driver logic block sets internal flip-flop when the 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 flip-flop resets, and external schottky diode turns on . This forces the current through the inductor to ramp 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 provides an electrical ON/OFF control of the power supply. Connecting this pin to ground or to any voltage less than 0.7V will completely turn OFF the regulator. In this state, current drain from the input supply is less than 1A, 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 EN low for shutdown. Soft-Start Soft-start allows a gradual increase of the internal current-limit level for the step-up converter during power-up to reduce input surge currents. As the internal current source charges the internal soft-start capacitor, the peak N-MOS current is limited by the voltage on the capacitor. Cycle-by-Cycle Over-Current Protection The AT1309 provides cycle-by-cycle over-current protection. Current limit is accomplished using a separate dedicated comparator. The cycle-by-cycle current limit abbreviates the on-time of the N-MOS in event 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 limits total power dissipation in the AT1309. When the junction temperature exceeds Tj=130 , a thermal sensor activates the thermal protection, which shuts down the IC, allowing the IC to cool. Once the device cools down by 10 , IC will automatically recover normal operation. For continuous operation , do not exceed the absolute maximum junction-temperature rating of Tj=120 .
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 9
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter Power dissipation consideration The AT1309 maximum power dissipation depends on the thermal resistance of the IC package and circuit board, the temperature 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 regulator. In continuous condition, the step-up converter power dissipated internally across the internal N-MOS can be approximated by : I x VO 2 1 Vin x D 2 ) ] x RDS (ON ) x D Pboost = [( O )+ ( Vin 12 f OSC x L where IO : It is the load current. fOSC : It is a switching frequency.
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AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter Application Information External components of boost converter can be designed by performing simple calculations. Boost inductor Inductor selection depends on input voltage, output voltage, maximum output current, switching frequency and availability of inductor values. The following boost circuit equations are useful in choosing the inductor values based on the application. They allow the trading of peak current and inductor value while allowing for consideration of component availability and cost. The peak inductor current is given by:
I Lpeak = I LAVG + I LAVG = IO 1- D I L 2
where: IL is the inductor peak-to-peak current ripple and is decided by: V D I L = in x L f OSC D is the MOSFET turn on ratio and is decided by: V -V in D= O VO 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 IO, and peak current the same as the inductor's peak current and a voltage rating at least 1.5 times 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 worstcase minimum value of 1uF at the particular VOUT being set. Output ripple voltage requirements also determine the minimum value and type of capacitors. Output ripple voltage consists of two components the voltage drop caused by the switching current through the ESR of the output capacitor and the charging and discharging of the output capacitor: V - Vin IO VRIPPLE = I LPEAK x ESR + O x VO COUT x f OSC For low ESR ceramic capacitors, the output ripple is dominated by the charging 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 11
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter
Impacting frequency stability of the overall control loop, Ceramic capacitors are preferred on the output capacitance, but tantalum capacitor may also suffice. If it use tantalum capacitor on the output terminal, that in addition the capacitance parallel with feedback resistor network is necessary. These frequency response effects together with the internal frequency compensation circuitry of AT1308 modify the gain and phase shift of the closed loop system.
PCB layout guidelines Careful printed circuit layout is extremely important to avoid causing parasitical capacitance and line inductance. The following layout guidelines are recommended to achieve optimum performance. Please the boost converter diode and inductor 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 12
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter 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 13
AT1309
Preliminary Product Information Micro-Power Step up DC-DC Converter Reflow Profiles
Profile Feature
Sn-Pb Eutectic Assembly Large Body Small Body Pkg. thickness Pkg. thickness <2.5mm or Pkg. 2.5mm or Pkg. 3 volume 350mm3 volume <350mm 3C/second max.
Average ramp-up rate (TL to TP) Preheat -Temperature Min(Tsmin) -Temperature Max (Tsmax) -Time (min to max)(ts) Tsmax to TL -Ramp-up Rate Time maintained above: -Temperature (TL) -Time (tL) Peak Temperature(TP) Time within 5C of actual Peak Temperature (tP) Ramp-down Rate Time 25C to Peak Temperature
Pb-Free Assembly Large Body Small Body Pkg. thickness Pkg. thickness 2.5mm or Pkg. 2.5mm or Pkg. volume 350mm3 volume 350mm3 3C/second max.
100C 150C 60-120 seconds
150C 200C 60-180 seconds 3C/second max.
183C 60-150 seconds 225+0/-5C 10-30 seconds 240+0/-5C 10-30 seconds
217C 60-150 seconds 245+0/-5C 10-30 seconds 250+0/-5C 20-40 seconds
6C/second max. 6 minutes max.
3C/second 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 14

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