Datasheet AT1780 Datasheet (AIM)

AT1780

640kHz/1.2MHz,Low-Noise Step-Up

Current-Mode PWM Controller

Preliminary

Features

• 1.8A,0.21Ω,14V Power MOSFET

• Operating input voltage:2.6V to 12V
to 14V

• Adjustable Output from V

• 640kHz /1.2MHz pin selectable switching

Frequency

• 0.1μA shutdown Current

• Built-in Soft-Start function

• Small 8-Pin μMax Package

IN

Applications

• LCD Displays

• Digital Cameras

•

Portable Applications

• Hand-Held Devices

Block Diagram

General Description

The AT1780 is a current-mode step-up DC/DC
converter with a 1.8A, 0.21Ω 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.

.

2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] WWW: http://www.aimtron.com.tw
Fax: [phone] Email: [e-mail]

1

AT1780

640kHz/1.2MHz,Low-Noise Step-Up

Current-Mode PWM Controller

Pin Configuration

Preliminary

Ordering Information

Part number Package Marking

AT1780 8µMAX

Pin Description

Pin No. Symbol I/O Description

1 COMP - Compensation network connection.
2 FB I Output voltage feedback input
3 /SHDN I Shutdown control input, active low
4GND
5 LX O Switch Pin.
6VIN
7 FSLC I Frequency select input. Ground=640KHz, VIN=1.2MHz
8 SS — Soft-Start control pin.

Ground

-

Power supply pin.

-

2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] WWW: http://www.aimtron.com.tw
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2

AT1780

640kHz/1.2MHz,Low-Noise Step-Up

Current-Mode PWM Controller

Absolute Maximum Ratings

Preliminary

Rated ValueParameter Condition

Unit

Min. Max.

LX to GND — -0.3 +14 V
IN, /SHDN, FREG, FB to GND — -0.3 +8 V
SS, COMP to GND — -0.3 VIN+0.3 V
RMS LX pin current — — 1.2 A

Continuous power dissipation

8pin μMAX（TA=+70℃）

Operating temperature — -30 +85
Junction temperature — — +150
Storage temperature — -40 +150
Lead temperature — — +300

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.

—330 mW

0

C

0

C

0

C

0

C

Recommended Operating Conditions

(Ta=+250C)

Power supply voltage V
SS pin capacitance C
Phase compensation capacitance C
Phase compensation capacitance C
Phase compensation resistance R

Oscillation frequency

f
f

Operating temperature T

CC

PE

COMP1

COMP2

COMP

OSC1

OSC2

OP

Va lu esParameter Symbol

Min. Typ. Max.

2.5 -- 7

-- 0.033 --

-- 680 --

-- 20 --

-- 180 -- KΩ

540 708 740 kHz

1000 1220 1500 kHz

-30 +25 +85 °C

Unit

Ｖ

μＦ

pＦ
pＦ

2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] WWW: http://www.aimtron.com.tw
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3

AT1780

640kHz/1.2MHz,Low-Noise Step-Up

Current-Mode PWM Controller

Electrical Characteristics

(VIN = SHDN = 3V, FREQ = GND, TA =-20℃ to +85℃, unless otherwise noted. Typical values are at TA = +25℃.)

Preliminary

Entire device

Error amplifier

Sawtooth wave
oscillator (OSC)

N-CHANNEL
SWITCH

SOFT-START

CONTROL INPUTS

Va lu esParameter Symbol Condition

Unit

Min. Typ. Max.

Input Supply Range V

VIN Undervoltage
Lockout

IN

UVLO

V

rising, typical

IN

hysteresis is 40mV,LX
remains off below this

2.5 -- 7 V

2.25 2.46 2.52 V

level

Quiescent Current I

VFB = 1.3V, not
switching

IN

0.218 0.35
mA

VFB = 1.0V, switching 2.045 5

Shutdown Supply
Current

I

Feedback Voltage V

FB Input Bias Current I

Feedback-Voltage Line
Regulation

Transconductance gm

/SHDN = GND 16

IN

Level to produce

FB

V

= 1.24V

COMP

VFB = 1.25V 0 40 nA

FB

1.245 1.25 1.255 V

Level to produce
V

= 1.24V,

COMP

2.6V < V
ΔI = 5µA

< 5.5V

IN

0.05 0.15 %/V

-280-

μA

μmhos

Voltage Gain Av -- 500 V/V

Frequency fosc

Maximum Duty Cycle DC

Current Limit I

On-Resistance R

Leakage Current I

Current-Sense
Transresistance

LXOFF

R

Reset Switch
Resistance

Charge Current

Input Low Voltage V

Input High Voltage V

Hysteresis

FREQ Pull-Down
Current

/SHDN Input Current I

I

SHDN

FREQ = GND 540 650 740
FREQ = IN 1050 1200 1350
FREQ = GND 79 91.3 92
FREQ = IN 82.1

VFB = 1V, duty cycle =

LIM

65%

ILX = 1.2A

ON

1.7 - 2.5 A

VLX = 12V 0.01 20

CS

V
/SHDN, FREQ;

IL

V
/SHDN, FREQ;

IH

V

= 1.2V

SS

= 2.6V to 5.5V

IN

= 2.6V to 5.5V

IN

0.3 0.45 0.65 V/A

1.5 2.55 7

SHDN, FREQ 0.07×

FREQ

1.5 5 9

0.21 0.3

100

0.51×
V

IN

0.57×
V

IN

V

IN

0.001 1

kHz

%

Ω

μA

Ω

μA

V

V

V

μA

μA

2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] WWW: http://www.aimtron.com.tw
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4

AT1780

640kHz/1.2MHz,Low-Noise Step-Up

Current-Mode PWM Controller

Typical Application Circuit

Preliminary

2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] WWW: http://www.aimtron.com.tw
Fax: [phone] Email: [e-mail]

5

AT1780

640kHz/1.2MHz,Low-Noise Step-Up

Current-Mode PWM Controller

Small Outline 8-pin Plastic µMAX

Preliminary

SYMBOL

A 0.037 0.043 0.94 1.10 -

A1 0.002 0.006 0.05 0.15 -

B 0.010 0.014 0.25 0.36 ­C 0.005 0.007 0.13 0.18 ­D 0.116 0.120 2.95 3.05 -

e 0.0256 BSC 0.65 BSC ­E 0.116 0.120 2.95 3.05 ­H 0.188 0.198 4.78 5.03
L 0.016 0.026 0.41 0.66 -

α

S 0.207 BSC 0.525 BSC -

2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] WWW: http://www.aimtron.com.tw
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INCHES MILLIMETERS

MIN MAX MIN MAX

0° 6° 0° 6°

6

NOTES

AT1780

C

640kHz/1.2MHz,Low-Noise Step-Up

Current-Mode PWM Controller

Reflow Condition (IR/Convection or VPR Reflow)

Reference JEDEC Standard J-STD-020A

Preliminary

Classification Reflow Profiles

Convection or

IR/Convction

Average Heating Rate(180°C to peak) 5°C/second max. 10°C/second max.
Preheat Temperature(125±20°C)
Temperature maintained above 180°C
Time within 5°C of actual Peak

Temperature
Peak Temperature Range(Note 1)

Cooling Rate
Time 25°C to Peak Temperature

*1 The maximum peak temperatures for IR and VP reflow are depending on package dimensions.

120 seconds max.
10~150 seconds
10~20 seconds 60 seconds

219~225°C or
235~240°C
6°C /second max. 10°C/second max.
6 minutes max.

219~225°C or
235~240°C

Package Reflow Conditions

Pkg. Thickness ≥2.5mm
and all bags

Convection 219~225
VPR 219~225

°C

IR/Convection 219~225

°C

°C

Pkg. Thickness <2.5mm
and

Pkg. Volume ≥350 mm

Pkg. Thickness <2.5mm
and

3

Pkg. Volume <350 mm

Convection 235~240
VPR 235~240
IR/Convection 235~240

VPR

3

°C

°C

°

2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] WWW: http://www.aimtron.com.tw
Fax: [phone] Email: [e-mail]

7

AT1780

640kHz/1.2MHz,Low-Noise Step-Up

Current-Mode PWM Controller

Preliminary

2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] WWW: http://www.aimtron.com.tw
Fax: [phone] Email: [e-mail]

8