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AT1780
Preliminary Product Information 640kHz/1.2MHz,Low-Noise Step-Up Current-Mode PWM Controller Features
* 1.6A,0.21,14V Power MOSFET * Operating input voltage:+2.6V to +5.5V * Adjustable Output from VIN to 12V * 640kHz /1.2MHz pin selectable switching Frequency * 0.1A shutdown Current * Built-in Soft-Start function * Small 8-Pin MSOP Package
General Description
The AT1780 is a current-mode step-up DC/DC converter with a 1.6A, 0.21 power MOSFET. The soft-start function is programmed with an external capacitor, which sets the input current ramp rate. It is ideal for generating bias voltages for LCD panels. Pin selectable frequency 640KHz or 1.2MHz operation results in a low noise output that is easy to filter and faster loop performance. An external compensation pin provides the user flexibility in determining loop dynamics, allowing the use of small, low equivalent series resistance (ESR) ceramic output capacitors. *Protected by U.S. Patent # 6,791,368
Applications
* LCD Displays * Digital Cameras * Portable Applications * Hand-Held Devices
Block Diagram
VIN COMP
SHDN
Power ON/OFF
Reference 1.24V
SOFTSTART
4uA SS
BIAS
+
Enable
Error Amplifier FB 1.24V gm + + Clock Comparator R Q N LX
S GND
FSLC
Oscillator
Ramp Generator
+ + CURRENT SENSE
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 3/24/06 REV 1.1 Email: service@aimtron.com.tw 1
AT1780
Preliminary Product Information 640kHz/1.2MHz,Low-Noise Step-Up Current-Mode PWM Controller Pin Configuration
8
7
6
5
1780
1 2 3 4
Ordering Information
Part number AT1780M_GRE Package MSOP8,Green Marking 1780,data code with one bottom line
*For more marking information, contact our sales representative directly
Pin Description
Pin No. Symbol I/O Description
1 2 3 4 5 6 7 8
COMP FB /SHDN GND LX VIN FSLC SS
I I O I --
Compensation network connection. Output voltage feedback input Shutdown control input, active low Ground Switch Pin. Power supply pin. Frequency select input. Ground=640KHz, VIN=1.2MHz Soft-Start control pin.
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 3/24/06 REV 1.1 Email: service@aimtron.com.tw 2
AT1780
Preliminary Product Information 640kHz/1.2MHz,Low-Noise Step-Up Current-Mode PWM Controller Absolute Maximum Ratings
Parameter LX to GND IN, /SHDN, FREG, FB to GND SS, COMP to GND RMS LX pin current Continuous power dissipation Operating temperature Junction temperature Storage temperature Lead temperature Condition -- -- -- -- 8pin MAXTA=+70 -- -- -- -- Rated Value Min. Max. -0.3 +14 -0.3 +6 -0.3 VIN+0.3 -- 1.2 -- 330 -30 +85 -- +150 -40 +150 -- +300 Unit V V V A mW 0 C 0 C 0 C 0 C
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.
Recommended Operating Conditions
(Ta=+250C)
Parameter Power supply voltage SS pin capacitance Phase compensation capacitance Phase compensation capacitance Phase compensation resistance Oscillation frequency Operating temperature
Symbol VIN CPE CCOMP1 CCOMP2 RCOMP fOSC1 fOSC2 TOP Min. 2.6 ----540 1000 -30
Values Typ. -0.033 470 18 30 640 1220 +25 Max. 5.5 ----740 1500 +85
Unit p p K kHz kHz C
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 3/24/06 REV 1.1 Email: service@aimtron.com.tw 3
AT1780
Preliminary Product Information 640kHz/1.2MHz,Low-Noise Step-Up Current-Mode PWM Controller Electrical Characteristics
(VIN = SHDN = 3V, FREQ = GND, TA =0 to +85, unless otherwise noted. Typical values are at TA = +25.)
Parameter Input Supply Range
Symbol VIN
Condition 2.6 VIN rising, typical hysteresis is 40mV,LX remains off below this level VFB = 1.3V, not switching VFB = 1.0V, switching /SHDN = GND Level to produce 1.222 VCOMP = 1.24V VFB = 1.25V Level to produce VCOMP = 1.24V, 2.6V < VIN < 5.5V I = 5A -FSLC = GND 540 FSLC = IN 1050 FSLC = GND 79 FSLC = IN VFB = 1V, duty cycle = 1.2 65% ILX = 1.2A VLX = 12V 0.3 2.1
Values Min. Typ. Max. 5.5 2.3 2.5
Unit V V
VIN Undervoltage UVLO Lockout Entire device Quiescent Current Shutdown Supply Current Feedback Voltage FB Input Bias Current Error amplifier Feedback-Voltage Line Regulation Transconductance Voltage Gain Sawtooth wave oscillator (OSC) Frequency Maximum Duty Cycle Current Limit N-CHANNEL SWITCH On-Resistance Leakage Current Current-Sense Transresistance Reset Switch Resistance Charge Current Input Low Voltage Input High Voltage CONTROL INPUTS Hysteresis FSLC Pull-Down Current /SHDN Input Current gm Av fosc DC ILIM RON ILXOFF RCS IIN IIN VFB IFB
0.218 0.35 2.045 0.1 5 10
mA A V nA
1.24 1.258 0 40
0.05 0.15 %/V
mhos 140 500 V/V 640 740 kHz 1200 1350 91.3 92 % 82.1
1.6 0.21 0.01
2.3 0.5 20
A A
0.45 0.65 V/A 100 A V V mV 5 0.001 9 1 A A
SOFT-START
VIL VIH
VSS = 1.2V /SHDN, FREQ; VIN = 2.6V to 5.5V /SHDN, FREQ; VIN = 2.6V to 5.5V SHDN, FREQ
1.5
4
7 0.4
1.6 100 1.5
IFSLC ISHDN
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 3/24/06 REV 1.1 Email: service@aimtron.com.tw 4
AT1780
Preliminary Product Information 640kHz/1.2MHz,Low-Noise Step-Up Current-Mode PWM Controller Typical Characteristics
(VIN = 3.3V, FREQ = GND, TA=25, unless otherwise noted.)
Efficiency vs. Output current
95
AT1780
Efficiency vs. Output current
95
AT1780
90
90
85 Efficiency Eff (%) Efficiency Eff (%) Vin=3.3V Vout=10V fosc=640kHz L=10uH 1 10 100 Output current Iout (mA) 1000
85
80
80
75
75
70
70 Vin=3.3V Vout=10V fosc=1.2MHz L=4.7uH 1 10 100 Output current Iout (mA) 1000
65
65
Output voltage vs. Output current
10.10
AT1780
Output voltage vs. Output current
10.10 10.05 Output voltage Vout (V) 10.00 9.95 9.90 9.85 9.80 9.75 9.70 9.65 Vin=3.3V Vout=10V fosc=1.2MHz L=4.7uH 0 40 80 120 160 200 Output current Iout (mA) 240
AT1780
10.05 Output voltage Vout (V) 10.00 9.95 9.90 9.85 9.80 9.75 9.70 9.65 Vin=3.3V Vout=10V fosc=640kHz L=10uH 0 40 80 120 160 200 Output current Iout (mA)
240
CH1:Output voltage,100mV/div/AC CH4:Output current,100mA/div/DC Vout=10V,fosc=640kHz,L=10uH R1=100k,C1=470PF,C2=18PF
CH1:Output voltage,100mV/div/AC CH4:Output current,100mA/div/DC Vout=10V,fosc=1.2MHz,L=4.7uH R1=100k,C1=470PF,C2=18PF
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 3/24/06 REV 1.1 Email: service@aimtron.com.tw 5
AT1780
Preliminary Product Information 640kHz/1.2MHz,Low-Noise Step-Up Current-Mode PWM Controller Typical Characteristics (continuted)
CH1:LX voltage,5V/div/DC CH4:Inductor current,500mA/div/DC Vout=10V,fosc=640kHz,L=10uH
CH1:LX voltage,5V/div/DC CH4:Inductor current,500mA/div/DC Vout=10V,fosc=1.2MHz,L=4.7uH
CH1:LX voltage,5V/div/DC CH2:Vin and /SHDN voltage,2V/div/DC CH3:SS voltage,2V/div/DC CH4:Iin current,500mA/div/DC Vout=10V,Iout=100mA, fosc=640kHz,L=10uH
CH1:LX voltage,5V/div/DC CH2:Vin and /SHDN voltage,2V/div/DC CH1:SS voltage,2V/div/DC CH4:Iin current,500mA/div/DC Vout=10V,Iout=100mA, fosc=1.2MHz,L=4.7uH
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 3/24/06 REV 1.1 Email: service@aimtron.com.tw 6
AT1780
Preliminary Product Information 640kHz/1.2MHz,Low-Noise Step-Up Current-Mode PWM Controller Typical Application Circuit
Vin 2.6V to 5.5V
Cin L1 D1
Vout
Cout Aimtron
VIN /SHDN COMP GND
R1
Cout
AT1780
LX FB FLSC SS 5 2 7 8
6 3
C1 0.1UF
1 4
R2
Rcomp
Css Ccomp1
Ccomp
Figure 1.Typical application circuit
Vin 3.0V to 3.6V
4.7UH
CRS01
VAA 10V/150mA 10UF 332K 10UF
22UF
6 3
Aimtron
VIN /SHDN COMP GND
AT1780
LX FB FLSC SS 5 2 7 8
47K D2 0.1UF 0.1UF D5 D3 D4 VGH 30V/5mA 1UF
C1 0.1UF
1 4
30K 18PF 470PF 0.033UF
1UF
0.1UF
D7
VGL -10V/10mA 4.7UF
D6
Figure 2.TFT panel power supply application circuit
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 3/24/06 REV 1.1 Email: service@aimtron.com.tw 7
AT1780
Preliminary Product Information 640kHz/1.2MHz,Low-Noise Step-Up Current-Mode PWM Controller
Small Outline
8-pin Plastic MAX
D S
8
7
6
5
5
5
7
8
E
H
1
2
3
4
4
3
2
1
A A1 B e C L
SYMBOL A A1 B C D e E H L S
INCHES MIN MAX 0.037 0.043 0.002 0.006 0.010 0.014 0.005 0.007 0.116 0.120 0.0256 BSC 0.116 0.120 0.188 0.198 0.016 0.026 0 6 0.207 BSC
MILLIMETERS MIN MAX 0.94 1.10 0.05 0.15 0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0 6 0.525 BSC
NOTES -
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 3/24/06 REV 1.1 Email: service@aimtron.com.tw 8
AT1780
Preliminary Product Information 640kHz/1.2MHz,Low-Noise Step-Up Current-Mode PWM Controller Reflow Profiles
Profile Feature
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
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.
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 3/24/06 REV 1.1 Email: service@aimtron.com.tw 9

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