Linear Technology LT1534-1, LT1534 Datasheet

FEATURES

■

Greatly Reduced Conducted and Radiated EMI

■

Low Switching Harmonic Content

■

Independent Control of Switch Voltage and Current Slew Rates

■

2A Current Limited Power Switch

■

Regulates Positive and Negative Voltages

■

20kHz to 250kHz Oscillator Frequency

■

Easily Synchronized to External Clock

■

Wide Input Voltage Range: 2.7V to 23V

■

Low Shutdown Current: 12µA Typical

■

Easier Layout than with Conventional Switchers

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APPLICATIO S

■

Precision Instrumentation Systems

■

Isolated Supplies for Industrial Automation

■

Medical Instruments

■

Wireless Communications

■

Single Board Data Acquisition Systems

LT1534/LT1534-1 Ultralow Noise

2A Switching Regulators

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DESCRIPTIO

The LT®1534/LT1534-1 are a new class of switching regulator designed to reduce conducted and radiated electromagnetic interference (EMI). Ultralow noise and EMI are achieved by providing user control of the output switch slew rates. Voltage and current slew rates can be independently programmed to optimize switcher harmonic content versus efficiency. The LT1534/LT1534-1 can reduce high frequency harmonic power by as much as 40dB with only minor losses in efficiency.

The LT1534/LT1534-1 utilize a current mode architecture optimized for low noise boost topologies. The ICs include a 2A power switch along with all necessary oscillator, control and protection circuitry. Unique error amp circuitry can regulate both positive and negative voltages. The internal oscillator may be synchronized to an external clock for more accurate placement of switching harmonics. Protection features include cycle-by-cycle current limit protection, undervoltage lockout and thermal shutdown.

Low minimum supply voltage and low supply current during shutdown make the LT1534/LT1534-1 well suited for portable applications. The LT1534/LT1534-1 are available in the 16-pin narrow SO package.

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

TYPICAL APPLICATION

L1

3.3V

50µH

+

220pF

C 33µF

6.3V

3300pF

IN

16.9k

6.8k

15nF

12

SHDN

4

SYNC

5

C

6

R

11

V

15

V

T

C

GND

IN

LT1534-1

9,16

PGND

NFB

R

101,8,

COL

VSL

CSL

2

3

14

13

7

FB

2.49k

Figure 1. Low Noise 3.3V to 5V Boost Converter

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1N5817

10Ω

L2

24k

A

C1

+

47µF

6.3V ×2

1nF

7.5k

CIN: MATSUSHITA ECGCOJB330 C1, C2: MATSUSHITA ECGCOJB47O L1, L3: COILTRONICS CTX50-4 L2: COILCRAFT B08T (28nH) OR PC TRACE

1534 TA01

L3

50µH

OPTIONAL

B

+

C2 47µF

5V 650mA

50mV/DIV

2mV/DIV

5V Output Noise (BW = 100MHz)

A

B

10µs/DIV

1534 TA02

1

LT1534/LT1534-1

WW

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ABSOLUTE MAXIMUM RATINGS

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(Note 1)

Input Voltage (VIN) .................................................. 30V

Switch Voltage (COL) .............................................. 35V

SHDN Pin Voltage.................................................... 30V

Feedback Pin Current (FB) .................................... 10mA

Negative Feedback Pin Current (NFB) .................. ±10mA

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PACKAGE/ORDER INFORMATION

ORDER PART

NUMBER

LT1534CS LT1534IS

1

NC

2

COL

3

*NC

4

SYNC

5

C

T

6

R

T

7

FB

8

NFB

16-LEAD PLASTIC SO

*DO NOT CONNECT

T

JMAX

TOP VIEW

16 15 14 13 12 11 10

9

S PACKAGE

= 125°C, θJA = 100°C/W

PGND COL V

IN

R

VSL

R

CSL

SHDN V

C

GND

Operating Junction Temperature Range

LT1534C................................................ 0°C to 125°C

LT1534I ............................................ –40°C to 125°C

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

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

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

TOP VIEW

1

GND

2

COL

3

PGND

4

SYNC

5

C

T

6

R

T

7

FB

8

GND

S PACKAGE

**FOUR CORNER PINS ARE FUSED TO INTERNAL

CONNECT THESE FOUR PINS TO EXPANDED

16-LEAD PLASTIC SO

DIE ATTACH PADDLE FOR HEAT SINKING.

PC LANDS FOR PROPER HEAT SINKING.

T

= 125°C, θJA = 50°C/W

JMAX

16

GND

15

V

IN

14

R

VSL

13

R

CSL

12

SHDN

11

V

C

10

NFB

9

GND

ORDER PART

NUMBER

LT1534CS-1 LT1534IS-1

Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C, VIN = 5V, VC = 0.9V, VFB = V

The ● denotes the specifications which apply over the full operating

. COL, SHDN, NFB, all other pins open

REF

unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Supply and Protection

V

IN

V

IN(MIN)

I

VIN

I

VIN(OFF)

V

SHDN

I

SHDN

Error Amplifiers

V

REF

I

FB

REG

Recommended Operating Range ● 2.7 23 V Minimum Input Voltage ● 2.55 2.7 V Operating Supply Current 2.7V ≤ VIN ≤ 23V, R Shutdown Supply Current 2.7V ≤ VIN ≤ 23V, V

2.7V ≤ V

≤ 23V, V

IN

, R

VSL

SHDN SHDN

, RT = 17k ● 12 30 mA

CSL

= 0V ● 12 50 µA

= 0V 12 30 µA Shutdown Threshold 2.7V ≤ VIN ≤ 23V ● 0.4 0.8 1.2 V Shutdown Input Current –2 µA

Reference Voltage Measured at Feedback Pin 1.235 1.250 1.265 V

● 1.215 1.250 1.275 V

Feedback Input Current VFB = V

REF

● 250 900 nA

Reference Voltage Line Regulation 2.7V ≤ VIN ≤ 23V ● 0.003 0.03 %/V

2

LT1534/LT1534-1

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C, VIN = 5V, VC = 0.9V, VFB = V

The ● denotes the specifications which apply over the full operating

. COL, SHDN, NFB, all other pins open

REF

unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Error Amplifiers

V

NFR

I

NFR

NFB

REG

g

m

I

ESK

I

ESRC

V

CLH

V

CLL

A

V

Oscillator and Sync

f

MAX

f

SYNC

R

SYNC

V

FBfs

Output Switches

DC

MAX

t

IBL

BV

COL

R

ON

I

LIM

∆IIN/∆I

Slew Control

V

SLEWR

V

SLEWF

I

SLEWR

I

SLEWF

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

Negative Feedback Reference Voltage Measured at Negative Feedback Pin with ● –2.550 –2.500 –2.420 V

Feedback Pin Open

Negative Feedback Input Current V

NFB

= V

NFR

● –37 –25 µA

Negative Feedback Reference Voltage 2.7V ≤ VIN ≤ 23V ● 0.002 0.05 %/V Line Regulation

Error Amplifier Transconductance ∆IC = ±25µA 1100 1500 1900 µmho

● 700 2300 µmho

Error Amplifier Sink Current VFB = V Error Amplifier Source Current VFB = V

+ 150mV, VC = 0.9V, V

REF

– 150mV, VC = 0.9V, V

REF

= 1V ● 120 200 350 µA

SHDN

= 1V ● 120 200 350 µA

SHDN

Error Amplifier Clamp Voltage High Clamp, VFB = 1V 1.33 V Error Amplifier Clamp Voltage Low Clamp, VFB = 1.5V 0.1 V Error Amplifier Voltage Gain 180 250 V/V

Maximum Switch Frequency 250 kHz Synchronization Frequency Range f

= 250kHz ● 375 kHz

OSC

SYNC Pin Input Resistance 40 kΩ FB Pin Threshold for Frequency Shift 5% Reduction from Nominal 0.4 V

Maximum Switch Duty Cycle R

VSL

= R

CSL

= 4.9k, f

= 25kHz ● 88 91 %

OSC

Switch Current Limit Blanking Time 200 ns Output Switch Breakdown Voltage 2.7V ≤ VIN ≤ 23V ● 35 V Output Switch-On Resistance I

= 1.5A, Both COL Pins Tied Together ● 0.25 0.43 Ω

COL

Switch Current Limit Duty Cycle = 30% 2 A

Duty Cycle = 80% 1.6 A

Supply Current Increase During 16 mA/A

SW

Switch-On Time

Output Voltage Slew Rising Edge R Output Voltage Slew Falling Edge R Output Current Slew Rising Edge R Output Current Slew Falling Edge R

VSL

, R

= 17k 11 V/µs

CSL

, R

= 17k 14.5 V/µs

CSL

, R

= 17k 1.3 A/µs

CSL

, R

= 17k 1.3 A/µs

CSL

3

LT1534/LT1534-1

UW

TYPICAL PERFORMANCE CHARACTERISTICS

Minimum Input Voltage (VIN) vs Temperature

2.70

2.65

2.60

2.55

INPUT VOLTAGE (V)

2.50

2.45 –50

–25 25

0

JUNCTION TEMPERATURE (°C)

50

Feedback Voltage and Input Current vs Temperature

1.30

1.29

1.28

1.27

1.26

1.25

1.24

1.23

FEEDBACK VOLTAGE (V)

1.22

1.21

1.20 –50

0

–25 25

125

100

75

1534 G01

V

FB

I

FB

50

TEMPERATURE (°C)

75

150

100

125

1533 G04

Change in Maximum Switch

–100

–200

(mA)

–300

LIM

∆I

–400

–500

–600

150

Current (I

0

2.0

1.8

FEEDBACK INPUT CURRENT (µA)

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2 0

) vs Duty Cycle

LIM

125°C

20 40 60

DUTY CYCLE (%)

85°C

25°C

80

100

1533 G02

Negative Feedback Voltage and Input Current vs Temperature

–2.30

–2.35

–2.40

–2.45

–2.50

–2.55

–2.60

NEGATIVE FB VOLTAGE (V)

–2.65

–2.70

–25 25 75

–50

Output Switch Saturation Voltage vs Switch Current

0.8

0.7

0.6

0.5

0.4

0.3

SWITCH VOLTAGE (V)

0.2

0.1

0

TEMPERATURE (°C)

0.5 SWITCH CURRENT (A)

50

25°C

100

V

I

NFB

125

1.0

NFB

1533 G05

85°C

150

150°C

35

30

25

20

15

NFB IINPUT CURRENT (µA)

1.5

–40°C

2.0

1534 G03

Error Amplifier Transconductance vs Temperature

2000

gm = ∆IVC/∆V

1900 1800 1700 1600 1500 1400 1300 1200

TRANSCONDUCTANCE (mho)

1100 1000

–50 25 75 150

–25 0

FB

50

TEMPERATURE (°C)

4

100 125

1534 G08

Switching Frequency vs Feedback Pin Voltage

100

TA = 25°C

90 80 70 60 50 40 30 20

SWITCHING FREQUENCY (% TYPICAL)

10

0

0.1 FEEDBACK PIN VOLTAGE (V)

0.2

0.3 0.4

0.5

1533 G06

0.6

Error Amplifier Output Current (VC)

500 400 300 200 100

0 –100 –200 –300

ERROR AMPLIFIER OUTPUT (µA)

–400 –500

–400 –300 –200 –100

FEEDBACK PIN VOLTAGE FROM NOMINAL (mV)

–40°C

0 100 300

200

125°C

25°C

400

1534 G07

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TYPICAL PERFORMANCE CHARACTERISTICS

VC Pin Threshold and Clamp Voltage vs Temperature

1.6

1.4

1.2

1.0

0.8

0.6

PIN VOLTAGE (V)

C

V

0.4

0.2

0

–50 25 75

–25 0

VC PIN CLAMP

THRESHOLD

TEMPERATURE (°C)

VOLTAGE

VC PIN

50

100 125

1534 G09

0.5A/DIV

100mV/DIV

LT1534/LT1534-1

Load Transient Response

I

LOAD

V

OUT

VIN = 3.3V 500µs/DIV 1534 G10 V

= 5V (NODE A)

OUT

= 0.1A TO 0.5A

I

LOAD

FIGURE 1 CIRCUIT

Typical Output Switch Voltage and Current Slew Rates vs Slew Setting Resistance (R

40

I

35

30

25

20

15

VOLTAGE SLEW (V/µs)

10

5

0

0 1/20k 1/10k 1/6.7k 1/5k

I V V

RISE FALL

1/R (mmho)

VSL

= R

CSL

TA = 25°C

(%)

OUT

∆V

–0.5

)

4

CURRENT SLEW (A/µs)

3

2

1

0

1534 G11

Load Regulation

2.0

1.5

1.0

0.5

0

FIGURE 1 CIRCUIT

Percent Change in Oscillator Frequency vs Temperature (NPO Cap and Metal Film R)

2.0

1.5

1.0

0.5

0

–0.5

–1.0

CHANGE IN FREQUENCY (%)

–1.5

–2.0

–50

–25 25

0

TEMPERATURE (°C)

50

125

100

75

1534 G12

–1.0

–1.5

0

100 300

200

LOAD CURRENT (mA)

400

500

600

700

1534-1 G13

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Linear Technology LT1534-1, LT1534 Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual