# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

LINEAR TECHNOLOGY LT1946A Data Sheet

Summary

The LT1946A is a high-efficiency step-up DC/DC converter featuring an integrated 1.5A switch and sophisticated Soft-Start functionality, delivering adjustable power up to 35V. Ideal for powering large TFT-LCD panels, GPS receivers, and other low-voltage communication modules. This manual serves as comprehensive technical documentation for system designers, detailing critical electrical characteristics, application circuits, efficiency curves, and performance guarantees needed to implement robust, highly reliable power solutions in professional electronics designs.

📄 Preview PAGE OF 12

Page 1 Text Content

LT1946A

2.7MHz Boost DC/DC Converter with 1.5A Switch and Soft-Start

FEATURES DESCRIPTIO 1.5A, 36V Internal Switch The LT®1946A is a fixed frequency step-up DC/DC con- 2.7MHz Switching Frequency verter containing an internal 1.5A, 36V switch. Capable of Integrated Soft-Start Function generating 12V at 430m A from a 5V input, the LT1946A is Adjustable Output from VIN to 35V ideal for powering large TFT-LCD panels. The LT1946A

Low VCESAT Switch: 300m V at 1.5A (Typical) switches at 2.7MHz, allowing the use of tiny, low profile 12V at 430m A from a 5V Input inductors and low value ceramic capacitors. Loop com- Small Thermally Enhanced 8-Lead MSOP Package pensation can be either internal or external, giving the user flexibility in setting loop compensation and allowing opti- mized transient response with low ESR ceramic output

APPLICATIO S

capacitors. Soft-start is controlled with an external capaci- tor which determines the input current ramp rate during

TFT-LCD Bias Supplies

start up. The 8-lead MSOP package and high switching

GPS Receivers EF FI CI EN CY

frequency ensure a low profile overall solution less than

DSL Modems

1.1mm high.

Local Power Supply

, LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATIO

D1 Efficiency

2.2µH VOUT

VIN SW

OFF ON SHDN C1 LT1946A FB 2.2µF C2

VC COMP

GND*SS

CC CSS 270p F 100n F

C1: 2.2µF, X5R or X7R, 6.3V 1946A TA01

C2: 2.2µF, X5R or X7R, 16V D1: MICROSEMI UPS120 OR EQUIVALENT L1: SUMIDA CR43-2R2 * EXPOSED PAD MUST ALSO BE GROUNDED

LOAD CURRENT (m A)

Figure 1. 5V to 12V, 430m A Step-Up DC/DC Converter 1946A TA01

sn1946a 1946afs

Page Summary Contents For LINEAR TECHNOLOGY LT1946A Data Sheet

Page 1 LT1946A 2.7MHz Boost DC/DC Converter with 1.5A Switch and Soft-Start FEATURES DESCRIPTIO 1.5A, 36V Internal Switch The LT®1946A is a fixed frequency step-up DC/DC con- 2.7MHz Switching Frequency verte...
Page 2 LT1946A ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) ORDER PART VIN Voltage 16V TOP VIEW NUMBER SW Voltage ................................................–0.4V to 36V VC SS FB Voltage 2.5...
Page 3 ES AT (V FE ED BA CK OL TA GE (V LT1946A TYPICAL PERFOR A CE CHARACTERISTICS Feedback Pin Voltage Oscillator Frequency Current Limit 1.28 2.6 2.2 TA = –30°C TA = 100°C 2.0 TA = 25°C 1.2 1.23 1.0 OS CI...
Page 4 LT1946A PI FU CTIO S VC (Pin 1): Error Amplifier Output Pin. Tie external com- SW (Pin 5): Switch Pin. This is the collector of the internal pensation network to this pin or use the internal compen- N...
Page 5 LT1946A BLOCK DIAGRA SS VC COMP COMPARATOR DRIVER REFERENCE R1 (EXTERNAL) GENERATOR 0.5V GND R2 (EXTERNAL) ÷ 3 2.7MHz OSCILLATOR EXPOSED PAD SHUTDOWN 1946A F02 Figure 2. Block Diagram sn1946a 1946afs
Page 6 LT1946A OPERATIO The LT1946A uses a constant frequency, current mode a nominal value of 0.5V. This is accomplished via com- control scheme to provide excellent line and load regula- parator A3. This f...
Page 7 LT1946A APPLICATIO S I FOR ATIO capacitor is sufficient for most applications, but systems with very low output currents may need only a 1µF or smaller output capacitor. Solid tantalum or OSCON ca- VO...
Page 8 LT1946A APPLICATIO S I FOR ATIO As with any feedback loop, identifying the gain and phase ESR Zero: Z contribution of the various elements in the loop is critical. ESR •π COUT Figure 4 shows the key e...
Page 9 LT1946A APPLICATIO S I FOR ATIO GA IN (f PH AS (f Setting Output Voltage To set the output voltage, select the values of R1 and R2 (see Figure 1) according to the following equation: OUT1 1=  . A ...
Page 10 LT1946A TYPICAL APPLICATIO S Low Profile (<1.1mm Tall) Triple Output TFT Supply (10V, –10V, 20V) D2 D3 VON VIN SW R1 75k OFF ON SHDN SS LT1946A FB VC GND* RC 10.5k EF FI CI EN CY CC C1–C6: X5R or X...
Page 11 LT1946A TYPICAL APPLICATIO S Triple Output TFT Supply Uses SEPIC Topology for Output Disconnect D2 VON VOFF –12V VIN SW 1µF OFF ON SHDN SS LT1946A FB COMP GND* C1–C5: X5R or X7R D1: MICROSEMI UPS120 O...
Page 12 LT1946A TYPICAL APPLICATIO S Low Profile (<1.1mm Tall) Triple Output TFT Supply (8V, –8V, 24V) D2 D3 D4 D5 VON Efficiency VIN SW OFF ON SHDN SS FBLT1946A VC GND* VON LOAD = 5m A VOFF LOAD = 10m A C...

Manual Details

Brand Linear
Pages 12
File Size 312.58 KB
Published June 17, 2026
1 views

Enter the captcha to get the download link:

captcha

Frequently Asked Questions

What is the operating temperature range for this converter?

The operating temperature range is –40°C to 85°C.

Does it have a soft-start function and how is it controlled?

Yes, it has integrated soft-start functionality. It is controlled by an external capacitor which determines the input current ramp rate.

How low can the device detect a switch point?

The device switches at 300mV with a current of 1.5A (typical).

What are the recommended types for capacitors C1 and C2?

C1 should be X5R or X7R, 6.3V, and C2 should be X5R or X7R, 16V.