LINEAR TECHNOLOGY LT1930, LT1930A Technical data

LT1930/LT1930A

1A, 1.2MHz/2.2MHz,

Step-Up DC/DC Converters

FEATURES

■

1.2MHz Switching Frequency (LT1930)

■

2.2MHz Switching Frequency (LT1930A)

■

Low V

■

High Output Voltage: Up to 34V

■

5V at 480mA from 3.3V Input (LT1930)

■

12V at 250mA from 5V Input (LT1930A)

■

Wide Input Range: 2.6V to 16V

■

Uses Small Surface Mount Components

■

Low Shutdown Current: <1µA

■

Low Profile (1mm) ThinSOTTM Package

■

Pin-for-Pin Compatible with the LT1613

Switch: 400mV at 1A

CESAT

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APPLICATIO S

■

TFT-LCD Bias Supply

■

Digital Cameras

■

Cordless Phones

■

Battery Backup

■

Medical Diagnostic Equipment

■

Local 5V or 12V Supply

■

External Modems

■

PC Cards

■

xDSL Power Supply

, LTC and LT are registered trademarks of Linear Technology Corporation

ThinSOT is a trademark of Linear Technology Corporation.

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in ThinSOT

DESCRIPTIO

The LT®1930 and LT1930A
power SOT-23 switching regulators. Both include an
internal 1A, 36V switch allowing high current outputs to be
generated in a small footprint. The LT1930 switches at

1.2MHz, allowing the use of tiny, low cost and low height
capacitors and inductors. The faster LT1930A switches at

2.2MHz, enabling further reductions in inductor size.
Complete regulator solutions approaching one tenth of a
square inch in area are achievable with these devices.
Multiple output power supplies can now use a separate
regulator for each output voltage, replacing cumbersome
quasi-regulated approaches using a single regulator and
custom transformers.

A constant frequency internally compensated current mode
PWM architecture results in low, predictable output noise
that is easy to filter. Low ESR ceramic capacitors can be
used at the output, further reducing noise to the millivolt
level. The high voltage switch on the LT1930/LT1930A is
rated at 36V, making the device ideal for boost converters
up to 34V as well as for single-ended primary inductance
converter (SEPIC) and flyback designs. The LT1930 can
generate 5V at up to 480mA from a 3.3V supply or 5V at
300mA from four alkaline cells in a SEPIC design.

The LT1930/LT1930A are available in the 5-lead ThinSOT
package.

are the industry’s highest

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TYPICAL APPLICATIO

L1

V

IN

5V

C1

2.2µF

SHDN

C1: TAIYO-YUDEN X5R LMK212BJ225MG
C2: TAIYO-YUDEN X5R EMK316BJ475ML
D1: ON SEMICONDUCTOR MBR0520
L1: SUMIDA CR43-100
*OPTIONAL

10µH

51

V

IN

LT1930

4

SHDN FB

GND

2

Figure 1. 5V to 12V, 300mA Step-Up DC/DC Converter

SW

D1

R1
113k

3

R2

13.3k

C3*
10pF

V
12V
300mA

C2

4.7µF

1930/A F01

OUT

90

85

80

75

70

65

EFFICIENCY (%)

60

55

50

0

Efficiency

VIN = 3.3V

100

200

LOAD CURRENT (mA)

VIN = 5V

300

400

1930 TA01

1

LT1930/LT1930A

PACKAGE/ORDER I FOR ATIO

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W

WWWU

ABSOLUTE AXI U RATI GS

(Note 1)

VIN Voltage .............................................................. 16V

SW Voltage ................................................–0.4V to 36V

FB Voltage .............................................................. 2.5V

Current Into FB Pin .............................................. ±1mA

SHDN Voltage ......................................................... 10V

Maximum Junction Temperature ......................... 125°C

Operating Temperature Range (Note 2) .. –40°C to 85°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec)..................300°C

TOP VIEW

SW 1

GND 2

FB 3

S5 PACKAGE

5-LEAD PLASTIC SOT-23

T

= 125°C, θJA = 256°C/W

JMAX

Consult LTC Marketing for parts specified with wider operating temperature ranges.

5 V

IN

4 SHDN

ORDER PART

NUMBER

LT1930ES5
LT1930AES5

S5 PART MARKING

LTKS
LTSQ

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C.
VIN = 3V, V

PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS

Minimum Operating Voltage 2.45 2.6 2.45 2.6 V
Maximum Operating Voltage 16 16 V
Feedback Voltage 1.240 1.255 1.270 1.240 1.255 1.270 V

FB Pin Bias Current VFB = 1.255V ● 120 360 240 720 nA
Quiescent Current V
Quiescent Current in Shutdown V
Reference Line Regulation 2.6V ≤ VIN ≤ 16V 0.01 0.05 0.01 0.05 %/V
Switching Frequency 1 1.2 1.4 1.8 2.2 2.6 MHz

Maximum Duty Cycle ● 84 90 75 90 %
Switch Current Limit (Note 3) 1 1.2 2 1 1.2 2.5 A
Switch V

CESAT

Switch Leakage Current VSW = 5V 0.01 1 0.01 1 µA
SHDN Input Voltage High 2.4 2.4 V
SHDN Input Voltage Low 0.5 0.5 V
SHDN Pin Bias Current V

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: The LT1930E/LT1930AE are guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –40°C to 85°C

= VIN unless otherwise noted. (Note 2)

SHDN

= 2.4V, Not Switching 4.2 6 5.5 8 mA

SHDN

= 0V, VIN = 3V 0.01 1 0.01 1 µA

SHDN

ISW = 1A 400 600 400 600 mV

= 3V 16 32 35 70 µA

SHDN

= 0V 0 0.1 0 0.1 µA

V

SHDN

LT1930 LT1930A

● 1.230 1.280 1.230 1.280 V

● 0.85 1.6 1.6 2.9 MHz

operating temperature range are assured by design, characterization and
correlation with statistical process controls.

Note 3: Current limit guaranteed by design and/or correlation to static test.

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LT1930/LT1930A

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TYPICAL PERFOR A CE CHARACTERISTICS

Quiescent Current FB Pin Voltage SHDN Pin Current

7.0
NOT SWITCHING

6.5

6.0

5.5

5.0

4.5

4.0

QUIESCENT CURRENT (mA)

3.5

3.0

–50 –25

0 25 100

TEMPERATURE (°C)

LT1930A

LT1930

50 75

1930/A G01

1.28

1.27

1.26

1.25

FB VOLTAGE (V)

1.24

1.23

1.22
–50

–25

02550

TEMPERATURE (°C)

75 100

1930/A G02

90
80
70
60
50
40

30

20

SHDN PIN CURRENT (µA)

10

0

–10

0

LT1930A

LT1930

12 4

SHDN PIN VOLTAGE (V)

3

5

1930/A G03

6

Current Limit

1.6

1.4

1.2

1.0

0.8

0.6

CURRENT LI MIT (A)

0.4

0.2

0

10

3020 5040 7060 9080

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DUTY CYCLE (%)

1930/A G04

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Switch Saturation Voltage

0.45

0.40

0.35

0.30

0.25

(V)

0.20

CESAT

V

0.15

0.10

0.05

0

0

0.4 1.2

0.2 1.0
SWITCH CURRENT (A)

PI FU CTIO S

SW (Pin 1): Switch Pin. Connect inductor/diode here.
Minimize trace area at this pin to reduce EMI.

GND (Pin 2): Ground. Tie directly to local ground plane.

Oscillator Frequency

2.5

2.3
LT1930A

LT1930

25 50 75 100

TEMPERATURE (°C)

1930/A G06

0.6

0.8

1930/A G05

2.1

1.9

1.7

1.5

1.3

FREQUENCY (MHz)

1.1

0.9

0.7

0.5

–50 –25 0

SHDN (Pin 4): Shutdown Pin. Tie to 2.4V or more to enable
device. Ground to shut down.

V

(Pin 5): Input Supply Pin. Must be locally bypassed.

IN

FB (Pin 3): Feedback Pin. Reference voltage is 1.255V.

Connect resistive divider tap here. Minimize trace area at
FB. Set V

according to V

OUT

= 1.255V(1 + R1/R2).

OUT

3

LT1930/LT1930A

BLOCK DIAGRA

V

IN

5

V

OUT

R1 (EXTERNAL)

FB

R2 (EXTERNAL)

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1.255V

REFERENCE

1

+

A1

–

R

C

C

C

COMPARATOR

–

A2

+

RQ

S

DRIVER

SW

Q1

+

Σ

0.01Ω

–

RAMP

GENERATOR

SHUTDOWN

SHDN

4

FB

3

Figure 2. Block Diagram

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OPERATIO

The LT1930 uses a constant frequency, current-mode
control scheme to provide excellent line and load regula­tion. Operation can be best understood by referring to the
block diagram in Figure 2. At the start of each oscillator
cycle, the SR latch is set, which turns on the power switch
Q1. A voltage proportional to the switch current is added
to a stabilizing ramp and the resulting sum is fed into the
positive terminal of the PWM comparator A2. When this
voltage exceeds the level at the negative input of A2, the SR
latch is reset turning off the power switch. The level at the
negative input of A2 is set by the error amplifier A1, and is
simply an amplified version of the difference between the
feedback voltage and the reference voltage of 1.255V. In

2

GND

1.2MHz

OSCILLATOR*

*2.2MHz FOR LT1930A

1930/A BD

this manner, the error amplifier sets the correct peak
current level to keep the output in regulation. If the error
amplifier’s output increases, more current is delivered to
the output; if it decreases, less current is delivered. The
LT1930 has a current limit circuit not shown in Figure 2.
The switch current is constantly monitored and not al­lowed to exceed the maximum switch current (typically

1.2A). If the switch current reaches this value, the SR latch
is reset regardless of the state of comparator A2. This
current limit helps protect the power switch as well as the
external components connected to the LT1930.

The block diagram for the LT1930A (not shown) is iden­tical except that the oscillator frequency is 2.2MHz.

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