Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - DC/DC voltage regulator Converter/amplifier DFN 14

LTC3533

3533fc

For more information www.linear.com/LTC3533

Features

applications

Description

2A Wide Input Voltage

Synchronous Buck-Boost

DC/DC Converter

The LT C

3533 is a wide V

range, highly efﬁcient, ﬁxed

frequency, buck-boost DC/DC converter that operates

from input voltages above, below or equal to the output

voltage. The topology incorporated in the IC provides a

continuous transfer function through all operating modes,

making the product ideal for single cell lithium-ion/polymer

or multi-cell alkaline/NiMH applications where the output

voltage is within the input voltage range.

The LTC3533 features programmable Burst Mode oper

ation, extended V

and V

OUT

ranges down to 1.8V, and

increased output current. Switching frequencies up to

2MHz are programmed with an external resistor. The Burst

Mode threshold is programmed with a single resistor from

the BURST pin to GND.

Other features include 1µA shutdown current, short circuit

protection, programmable soft-start, current limit and

thermal shutdown. The LTC3533 is housed in the thermally

enhanced 14-lead (3mm × 4mm × 0.75mm) DFN package.

Efﬁciency

Regulated Output with Input Voltages Above,

Below or Equal to the Output

1.8V to 5.5V (Input) and 5.25V (Output)

Voltage Range

0.8A Continuous Output Current: V

> 1.8V

2A Continuous Output Current: V

> 3V

Single Inductor

Synchronous Rectiﬁcation: Up to 96% Efﬁciency

Programmable Burst Mode

Operation: I

= 40µA

Output Disconnect in Shutdown

Programmable Frequency from 300kHz to 2MHz

<1µA Shutdown Current

Small Thermally Enhanced 14-Lead (3mm × 4mm ×

0.75mm) DFN package

GSM Modems

Handheld Instruments

Digital Cameras

Smart Phones

Media Players

Miniature Hard Disk Drive Power

SW1

RUN/SS

SW2

OUT

LTC3533

10μF

2.4V TO 4.2V

340k 6.49k

100μF

47pF

OUT

3.3V

1.5A

200k

0.1μF

107k

330pF

4.7pF

3533 TA01

2.2

33.2k 200k

PGND

SGND

ONOFF

BURST

OUTPUT CURRENT (mA)

0.1

EFFICIENCY (%)

1 10 100 1000 10000

3533 TA01b

100

Burst Mode

OPERATION

= 3.9V

= 2.2V

= 2.9V

L, LT, LTC, LTM, Linear Technology, BurstMode and the Linear logo are registered trademarks

of Linear Technology Corporation. All other trademarks are the property of their respective owners.

typical application

Downloaded from Arrow.com.

Summary of content (18 pages)

PAGE 1
LTC3533 2A Wide Input Voltage Synchronous Buck-Boost DC/DC Converter Description Features n n n n n n n n n n n Regulated Output with Input Voltages Above, Below or Equal to the Output 1.8V to 5.5V (Input) and 5.25V (Output) Voltage Range 0.8A Continuous Output Current: VIN > 1.
PAGE 2
LTC3533 Absolute Maximum Ratings pin configuration (Note 1) TOP VIEW VIN, PVIN Voltages............................................–0.3 to 6V VOUT, PVOUT Voltages......................................–0.3 to 6V SW1, SW2 Voltages DC................................................................–0.3 to 6V Pulsed < 100ns............................................–0.3 to 7V VC, FB, RUN/SS, BURST Voltages...................–0.3 to 6 V Operating Temperature Range (Note 2)....
PAGE 3
LTC3533 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 3.6V, VOUT = 3.3V, unless otherwise noted. PARAMETER CONDITIONS Maximum Duty Cycle Boost (% Switch C On) Buck (% Switch A On) l l Minimum Duty Cycle Frequency Accuracy MIN TYP 80 100 90 l 0.7 1 UNITS % % 0 l RT = 33.2k MAX 1.
PAGE 4
LTC3533 Typical Performance Characteristics Quiescent Current vs VIN (Fixed Frequency Mode) 3.0 1.5 MHz 1.0 MHz 2.0 1.5 0.5 MHz 1.0 NO SWITCHING 50 5 45 4 40 3 CURRENT LIMIT CHANGE (%) VIN QUIESCENT CURRENT (μA) VIN QUIESCENT CURRENT (mA) 2.0 MHz 2.5 35 30 25 20 15 10 2 1 0 –1 –2 –3 0.5 5 –4 0.0 2.5 0 –5 –55 –35 –15 3.0 3.5 4.0 VIN (V) 4.5 5.0 5.5 2.5 3.0 3.5 4.0 VIN (V) 4.5 5.0 5.
PAGE 5
LTC3533 Typical Performance Characteristics TA = 25°C, unless otherwise specified. Switch Pins Entering Buck-Boost Mode Switch Pins in Buck-Boost Mode SW1 2V/DIV SW1 2V/DIV Output Ripple at 1A Load VIN = 2.7V VIN = 3.3V SW2 2V/DIV SW2 2V/DIV 50ns/DIV VIN = 3.3V VOUT = 3.3V AT 500mA VIN = 4.2V 3533 G10 50ns/DIV 3533 G11 VIN = 4.2V VOUT = 3.3V AT 500mA Load Transient Response in Fixed Frequency Mode, No Load to 1.5A 1μs/DIV VOUT = 3.
PAGE 6
LTC3533 Pin Functions RT (Pin 1): Programs the Frequency of the Internal Oscillator. Connect a resistor from RT to ground. f(kHz) = 33,170/RT (kΩ) BURST (Pin 2): Used to set the Automatic Burst Mode Threshold. Connect a resistor and capacitor in parallel from this pin to ground. See the Applications Information section for component value selection. For manual control, ground the pin to force Burst Mode operation, connect to VIN to force fixed frequency PWM mode. SGND (Pin 3): Signal ground for the IC.
PAGE 7
LTC3533 Block Diagram SW2 SW1 VOUT SW D SW B GATE DRIVERS AND ANTI-CROSS CONDUCTION –0.5A SW C – SW A ISENSE AMP + VIN 1.8V TO 5.5V REVERSE CURRENT LIMIT R1 + + SUPPLY CURRENT LIMIT + + ERROR AMP – – – 4.5A UVLO + RT VC + R2 OSC SLEEP BURST MODE OPERATION CONTROL BURST 0 = BURST MODE 1 = FIXED FREQUENCY CLAMP FB – – 1.6V RT PWM LOGIC AND OUTPUT PHASING PWM COMPARATORS 1.22V RUN GND RUN/SS RSS VIN CSS 3533 BD 3533fc For more information www.linear.
PAGE 8
LTC3533 operation The LTC3533 provides high efficiency, low noise power for a wide variety of handheld electronic devices. The LTC proprietary topology allows input voltages above, below or equal to the output voltage by properly phasing the output switches. The error amplifier output voltage on VC determines the output duty cycle of the switches. Since VC is a filtered signal, it provides rejection of frequencies well below the switching frequency.
PAGE 9
LTC3533 Operation PVIN PVOUT 11 9 PMOS A SW1 where D4SW = duty cycle % of the four switch range. D4SW = (150ns • f) • 100 % PMOS D L1 SW2 3 7 NMOS B NMOS C Figure 1. Simplified Diagram of Output Switches V4 (≈1.5V) A ON, B OFF BOOST REGION PWM CD SWITCHES DMIN BOOST DMAX BUCK V3 (≈1.15V) FOUR SWITCH PWM Beyond this point the “four switch,” or buck/boost region is reached. Buck/Boost or Four Switch (VIN ~ VOUT) 3533 F01 85% DMAX BOOST where f = operating frequency, Hz.
PAGE 10
LTC3533 Operation BURST MODE OPERATION Programmable Automatic Burst Mode Operation Burst Mode operation reduces the LTC3533’s quiescent current consumption at light loads and improves overall conversion efficiency, increasing battery life. During Burst Mode operation the LTC3533 delivers energy to the output until it is regulated and then goes into a sleep mode where the outputs are off and the quiescent current drops to 40µA.
PAGE 11
LTC3533 Operation Manual Burst Mode Operation For manual control of Burst Mode operation, the RC network connected to BURST can be eliminated. To force fixed frequency mode, BURST should be connected to VIN. To force Burst Mode operation, BURST should be grounded. When commanding Burst Mode operation manually, the circuit connected to BURST should be able to sink up to 2mA. For optimum transient response with large dynamic loads, the operating mode should be controlled digitally by the host.
PAGE 12
LTC3533 Applications Information COMPONENT SELECTION where f = switching frequency, Hz ∆IL = maximum allowable inductor ripple current 1 RT VC 14 VIN(MIN) = minimum input voltage 2 BURST FB 13 VIN(MAX) = maximum input voltage 3 SGND RUN/SS 12 4 SW1 PVIN 11 5 PGND VIN 10 6 PGND PVOUT 9 7 SW2 VOUT 8 GND VOUT = output voltage VIN VOUT MULTIPLE VIAS 3533 F04 Figure 4. Recommended Component Placement. Traces Carrying High Current Should be Short and Wide.
PAGE 13
LTC3533 Applications Information requirements of the converter. As a rule of thumb, the ratio of the operating frequency to the unity-gain bandwidth of the converter is the amount the output capacitance will have to increase from the above calculations in order to maintain the desired transient response. to provide the conduction path to the output. Note that Burst Mode operation is inhibited at output voltages below 1V typical.
PAGE 14
LTC3533 Applications Information Closing the Feedback Loop The LTC3533 incorporates voltage mode PWM control. The control to output gain varies with operation region (buck, boost, buck/boost), but is usually no greater than 15. The output filter exhibits a double pole response, as given by: f FILTER _POLE = 1 Hz 2 • π • L • COUT f UG = (in buckm ode) f FILTER _POLE = VIN Hz 2 • VOUT • π • L • COUT (in boostm ode) where L is in Henries and COUT is in Farads.
PAGE 15
LTC3533 Typical Applications High Efficiency, High Current LED Driver 3.3μH 11 VIN 3V TO 4.2V 10 OFF ON 12 4 7 SW1 SW2 PVIN PVOUT VIN VOUT ILED = 1A 8 4.7μF LTC3533 RUN/SS 9 FB 13 1nF 1 10μF RT VC BURST 44.2k SGND PGND 3 5 6 14 2 100k 95.3k 100k 47pF 301k 3533 TA02 3533fc For more information www.linear.com/LTC3533 Downloaded from Arrow.com.
PAGE 16
LTC3533 Package Description Please refer to http://www.linear.com/product/LTC3533#packaging for the most recent package drawings. DE Package 14-Lead Plastic DFN (4mm × 3mm) (Reference LTC DWG # 05-08-1708 Rev B) 0.70 ±0.05 3.30 ±0.05 3.60 ±0.05 2.20 ±0.05 1.70 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 3.00 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 ±0.10 (2 SIDES) R = 0.05 TYP 3.00 ±0.10 (2 SIDES) R = 0.115 TYP 8 0.40 ±0.10 14 3.30 ±0.
PAGE 17
LTC3533 Revision History (Revision history begins at Rev B) REV DATE DESCRIPTION B 01/16 Corrected part number in Order Information 2 Modified Burst Mode Operation 10 Moved application circuit to back page 18 Corrected part number in Order Information 2 C 08/16 PAGE NUMBER 3533fc Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 18
LTC3533 Typical Application 1MHz Li-Ion to 3.6V at 2A, Pulsed, with Manual Mode Control 6.8μH 11 VIN 3V TO 4.2V 10 12 OFF ON 1 10μF 4 7 SW1 SW2 PVIN PVOUT VIN VOUT LTC3533 RUN/SS FB RT VC BURST 64.9k SGND PGND 3 5 9 8 388k 220pF 13 14 2.2k VOUT 3.