Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - DC/DC voltage regulator Boost MSOP 10

LT1310

sn1310 1310fs

1.5A Boost

DC/DC Converter

with Phase-Locked Loop

The LT

1310 boost DC/DC converter combines a 1.5A

current mode PWM switcher with an integrated phase-

locked loop, allowing the user to set the switching fre-

quency anywhere from 10kHz to 4.5MHz. Intended for use

in applications where switching frequency must be accu-

rately controlled, the LT1310 can generate 12V at up to

400mA from a 5V input.

Switching frequency is set with an external capacitor, and

the device can be operated in either free-running or phase-

locked mode. A wide capture range of nearly 2:1 allows the

free-running frequency to be set using standard ±10%

tolerance NP0 dielectric capacitors.

The LT1310 is available in the tiny thermally enhanced

10-lead MSOP package.

■

Synchronizable or Constant Frequency

Low Noise Output

■

Synchronizable Up to 4.5MHz

■

Wide Input Voltage Range: 2.8V to 18V

■

Low Profile Surface Mount Solution

(All Ceramic Capacitors)

■

Low V

CESAT

Switch: 240mV at 1A

■

Adjustable Output from V

to 35V

■

Small Thermally Enhanced 10-Lead MSOP Package

■

Instruments

■

Avionics

■

Data Acquisition

■

Communications

■

Imaging

■

Ultrasound

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

SHDNSHUTDOWN

SYNC

1.6MHz

SYNC

PLL-LPF

3.01k

15k

178k

20.5k

100pF

NP0

1310 F01a

4.7µF

CERAMIC

OUT

12V

400mA

1500pF

820pF

C1: 4.7µF, X5R OR X7R, 6.3V

C2: 4.7µF, X5R OR X7R, 16V

D1: MICROSEMI UPS120 OR EQUIVALENT

L1: PANASONIC ELL6SH-5R6M

*EXPOSED PAD MUST ALSO BE GROUNDED

4.7µF

CERAMIC

LT1310

5.6µH

GND*

LOAD CURRENT (mA)

EFFICIENCY (%)

100 200

1310 F01b

400300

3.3V

OUT

= 12V

Figure 1. 5V to 12V Converter Synchronized at 1.6MHz

LT1310 Efficiency

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

Summary of content (12 pages)

PAGE 1
LT1310 1.5A Boost DC/DC Converter with Phase-Locked Loop U FEATURES ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LT®1310 boost DC/DC converter combines a 1.5A current mode PWM switcher with an integrated phaselocked loop, allowing the user to set the switching frequency anywhere from 10kHz to 4.5MHz. Intended for use in applications where switching frequency must be accurately controlled, the LT1310 can generate 12V at up to 400mA from a 5V input.
PAGE 2
LT1310 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) SW Voltage .............................................................. 36V VIN Voltage ............................................................. 18V SHDN Voltage ......................................................... 18V SYNC Voltage ........................................................... 5V FB Voltage ................................................................. 5V CT Voltage ...........................
PAGE 3
LT1310 U W TYPICAL PERFOR A CE CHARACTERISTICS Feedback Voltage Feedback Pin Current FEEDBACK CURRENT (nA) FB VOLTAGE (V) 1.26 1.25 1.24 Undervoltage Lockout 140 2.80 120 2.75 UNDERVOLTAGE LOCKOUT (V) 1.27 100 80 60 40 1.23 20 1.22 –50 0 25 50 TEMPERATURE (°C) –25 75 0 –50 100 –25 50 25 0 TEMPERATURE (°C) 75 1310 G01 2.60 2.55 2.
PAGE 4
LT1310 U W TYPICAL PERFOR A CE CHARACTERISTICS PLL Lock Range 220pF Capacitor on CT Pin Switch Minimum On Time PLL Lock Range 47pF Capacitor on CT Pin 100 1400 3500 90 1200 3000 80 70 60 MAXIMUM FREQUENCY (kHz) FREQUENCY (kHz) MINIMUM ON TIME (ns) MAXIMUM 1000 800 600 2500 2000 MINIMUM 1500 MINIMUM 50 40 –50 400 –25 0 25 50 TEMPERATURE (°C) 75 1000 200 –50 100 –25 75 0 25 50 TEMPERATURE (°C) 1310 G10 –25 0 25 50 TEMPERATURE (°C) 1310 G11 Supply Current 75 100 1310 G12 Sw
PAGE 5
LT1310 U U U PI FU CTIO S FB (Pin 1): Feedback Pin for Error Amplifier. Connect the resistor divider here to set output voltage according to the formula: VOUT R1 VOUT = 1.255(1 + R1/R2) FB R2 SYNC (Pin 4): Frequency Synchronization Pin. Inject the external synchronizing signal here. The phase detector is edge triggered and when locked the rising edge of the sync signal will be aligned with the turn-on of the power transistor. The SYNC signal must have a minimum HIGH amplitude of 1.
PAGE 6
LT1310 W BLOCK DIAGRA FB VC CT PLL-LPF 1 10 9 3 SYNC – + RAMP GEN. PHASE DETECTOR VCO 4 A1 Σ + + + – A2 1.255V REF S R Q Q SHDN 2 SW SHUTDOWN 6, 7 GND 5 EXPOSED PAD ×5 0.024Ω 1310 BD U OPERATIO To understand operation, refer to the Block Diagram. The LT1310 contains a boost switching regulator that can be phase locked to an external synchronizing signal. The boost regulator uses current mode control and contains a 1.5A NPN power transistor.
PAGE 7
LT1310 U OPERATIO CT Selection for Operating Frequency To synchronize to an external input signal, the timing capacitor and PLL filter components must be chosen properly. This is a simple process and can be done using the graph in Figure␣ 2a. In Figure 2a, operating frequency is plotted versus timing capacitor (CT) with the upper and lower lines corresponding to the minimum and maximum lock frequency given a specific CT value.
PAGE 8
LT1310 U W U U APPLICATIO S I FOR ATIO Inductor Selection Capacitor Selection Several inductors that work well with the LT1310 are listed in Table 2. This table is not exclusive; there are many other manufacturers and inductors that can be used. Consult each manufacturer for more detailed information and for their entire selection of related parts, as many different sizes and shapes are available.
PAGE 9
LT1310 U W U U APPLICATIO S I FOR ATIO fast current loop which does not require compensation, and a slower voltage loop which does. Standard Bode plot analysis can be used to understand and adjust the voltage feedback loop. VOUT 100mV/DIV AC COUPLED IL 0.5A/DIV RC = 3k 200µs/DIV 1310 F03a Figure 3a. Transient Response Shows Excessive Ringing VOUT 100mV/DIV AC COUPLED IL 0.
PAGE 10
LT1310 U W U U APPLICATIO S I FOR ATIO 100 – gmp VOUT COUT 1.
PAGE 11
LT1310 U W U U APPLICATIO S I FOR ATIO Layout Hints performance with careless layout. Figure 6 shows the recommended component placement for a boost converter. The high speed operation of the LT1310 demands careful attention to board layout. You will not get advertised CC R2 R1 RC VIN CIN CT LT1310 L1 SHDN SYNC SW RLP COUT MULTIPLE VIAS CLP D1 GND VOUT 1310 F06 Figure 6. Recommended Component Placement for Boost Converter. Note Direct High Current Paths Using Wide PC Traces.
PAGE 12
LT1310 U TYPICAL APPLICATIO 3MHz 5V to 12V Converter VIN 5V D1 LT1310 C1 2.2µF VIN SHUTDOWN SHDN SYNC IN SYNC PLL-LPF 3MHz R2 20.5k CT CT 33pF NP0 RC 10k CC 680pF 5VIN 85 80 75 FB GND* VC RLP 3.01k CLP 1000pF R1 178k SW 90 VOUT 12V 400mA EFFICIENCY (%) L1 3.3µH Efficiency 3.3VIN 70 65 60 55 50 C2 2.