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LTC1530

1530fa

The LTC

1530 is a high power synchronous switching

regulator controller optimized for 5V to 1.3V-3.5V output

applications. Its synchronous switching architecture drives

two external N-channel MOSFET devices to provide high

efficiency. The LTC1530 contains a precision trimmed

reference and feedback system that provides worst-case

output voltage regulation of ±2% over temperature, load

current and line voltage shifts. Current limit circuitry

senses the output current through the on-resistance of

the topside N-channel MOSFET, providing an adjustable

current limit without requiring an external low value sense

resistor.

The LTC1530 includes a fixed frequency PWM oscillator

that free runs at 300kHz, providing greater than 90%

efficiency in converter designs from 1A to 20A of output

current. Shutdown mode drops the LTC1530 supply cur-

rent to 45µA.

The LTC1530 is specified for commercial and industrial

temperature ranges and is available in the S0-8 package.

Figure 1. Single 5V to 3.3V Supply

LOAD CURRENT (A)

0.3

EFFICIENCY (%)

100

1530 F01b

= 25°C

Efficiency vs Load Current

■

High Power Buck Converter from 5V or 3.3V Input

■

Adjustable Current Limit in S0-8 with

Topside FET R

DS(ON)

Sensing

■

No External Sense Resistor Required

■

Hiccup Mode Current Limit Protection

■

Adjustable, Fixed 1.9V, 2.5V, 2.8V and 3.3V Output

■

All N-Channel MOSFET Synchronous Driver

■

Excellent Output Regulation: ±2% over Line, Load

and Temperature Variations

■

High Efficiency: Over 95% Possible

■

Fast Transient Response

■

Fixed 300kHz Frequency Operation

■

Internal Soft-Start Circuit

■

Quiescent Current: 1mA; 45µA in Shutdown

■

Power Supply for Pentium

II, AMD-K6

-2, SPARC,

ALPHA and PA-RISC Microprocessors

■

High Power 5V to 1.3V-3.5V Regulators

2.7k

0.1µF

10µF

OUT

330µF

× 7

1200µF

× 4

2µH

MBR0530T1 MBR0530T1

20Ω

GND

LTC1530-3.3

COMP

MAX

OUT

3.3V

14A

1530 F01a

: SANYO 10MV1200GX

OUT

: AVX TPSE337M006R0100

L1: COILTRONICS CTX02-13198

OR PANASONIC ETQP6F2R5HA

Q1, Q2: SILICONIX SUD50N03-10

10k

0.022µF

0.22µF

150pF

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

Pentium is a registered trademark of Intel Corp.

AMD-K6 is a registered trademark of Advanced Micro Devices, Inc.

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

High Power Synchronous

Switching Regulator Controller

Summary of content (24 pages)

PAGE 1
LTC1530 High Power Synchronous Switching Regulator Controller U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LTC®1530 is a high power synchronous switching regulator controller optimized for 5V to 1.3V-3.5V output applications. Its synchronous switching architecture drives two external N-channel MOSFET devices to provide high efficiency.
PAGE 2
LTC1530 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage PVCC ........................................................................ 14V Input Voltage IFB (Note 2) ............................................... PVCC + 0.3V IMAX ........................................................ – 0.3V to 14V IFB Input Current (Notes 2,3) ............................ – 100mA Operating Ambient Temperature Range LTC1530C ...............................................
PAGE 3
LTC1530 ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PVCC = 12V unless otherwise noted. (Note 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VOUT Output Voltage LTC1530IS8-1.9 (Note 4) ● 1.881 1.862 1.9 1.9 1.919 1.938 V V ● 2.475 2.450 2.5 2.5 2.525 2.550 V V ● 2.772 2.744 2.8 2.8 2.828 2.856 V V ● 3.267 3.234 3.3 3.3 3.333 3.366 V V LTC1530IS8-2.
PAGE 4
LTC1530 U W TYPICAL PERFOR A CE CHARACTERISTICS Load Regulation Efficiency vs Load Current 90 2.508 80 2.506 1.250 2.504 1.245 2.502 1.240 EFFICIENCY (%) 70 60 50 40 20 TA = 25°C REFER TO FIGURE 10 10 1.260 TA = 25°C REFER TO FIGURE 2 1.255 VSENSE (V) OUTPUT VOLTAGE (V) 2.510 30 2.500 2.498 0 0.3 2 8 4 10 6 LOAD CURRENT (A) 12 1.235 1.230 2.496 1.225 2.494 1.220 2.492 1.215 2.490 0 0 14 1 2 3 4 OUTPUT CURRENT (A) 5 1.210 –55 –35 –15 6 1530 G02 1530 G01 LTC1530-2.
PAGE 5
LTC1530 U W TYPICAL PERFOR A CE CHARACTERISTICS Oscillator Frequency vs Temperature 60 Maximum G1 Duty Cycle vs Ambient Temperature 92 350 55 50 45 MAXIMUM G1 DUTY CYCLE (%) 340 OSCILLATOR FREQUENCY (kHz) ERROR AMPLIFIER OPEN-LOOP DC GAIN (dB) Error Amplifier Open-Loop Gain vs Temperature 330 320 310 300 290 280 270 250 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 5 25 45 65 85 105 125 TEMPERATURE (°C) 1530 G10 200 180 160 50 40 30 20 PVCC = 12V 70 65 60 55 50 45 40 35 0 5 25 45
PAGE 6
LTC1530 U U U PI FU CTIO S PVCC (Pin 1): Power Supply for G1, G2 and Logic. PVCC must connect to a potential of at least VIN + VGS(ON)Q1. If VIN = 5V, generate PVCC using a simple charge pump connected to the switching node between Q1 and Q2 (see Figure 1) or connect PVCC to a 12V supply. Bypass PVCC properly or erratic operation will result. A low ESR 10µF capacitor or larger bypass capacitor along with a 0.
PAGE 7
LTC1530 W BLOCK DIAGRA DISDR LOGIC AND THERMAL SHUTDOWN INTERNAL OSCILLATOR 1 PVCC POWER DOWN 8 G1 – ICOMP PWM 7 G2 + COMP 4 ISS MSS FIXED VOUT R1 R2 1.9V 2.5V 2.8V 3.3V 23.4k 44.4k 54.9k 68.4k 43.2k 43.2k 43.2k 40.
PAGE 8
LTC1530 TEST CIRCUITS PVCC 12V 0.1µF 90% 10µF 50% PVCC G1 IFB COMP VOUT 10% G1 RISE/FALL G2 90% 50% 10% COMP 3300pF LTC1530 COMP tf tr + tNOL 50% G2 RISE/FALL tNOL 50% G1 3300pF GND t SS 1530 F04b 1530 F04a Figure 4 U W U U APPLICATIO S I FOR ATIO OVERVIEW The LTC1530 is a voltage feedback, synchronous switching regulator controller (see Block Diagram) designed for use in high power, low voltage step-down (buck) converters.
PAGE 9
LTC1530 U W U U APPLICATIO S I FOR ATIO Typically, thermal shutdown is activated if the LTC1530’s junction temperature exceeds 150°C. G1 and G2 resume switching when the junction temperature drops below 100°C. Soft-Start and Current Limit Unlike other PWM parts, the LTC1530 includes an on-chip soft-start capacitor that is used during start-up and current limit operation. On power-up, an internal 4µA pull-up at COMP brings the LTC1530 out of shutdown mode.
PAGE 10
LTC1530 U W U U APPLICATIO S I FOR ATIO For a given application, the input and output requirements are known and determine the main inductor and output capacitor values. These values establish the transient load recovery time. In general, a low value inductor combined with high value output capacitance has a short transient load recovery time at the expense of higher inductor ripple and start-up current (IRIPPLE and IST).
PAGE 11
LTC1530 U W U U APPLICATIO S I FOR ATIO In order for the current limit circuit to operate properly and to obtain a reasonably accurate current limit threshold, the IMAX and IFB pins must be Kelvin sensed at Q1’s drain and source pins. A 0.1µF decoupling capacitor can also be connected across RIMAX to filter switching noise. In addition, LTC recommends that the voltage drop across the RIMAX resistor be set to ≥100mV.
PAGE 12
LTC1530 U W U U APPLICATIO S I FOR ATIO either Q1 or Q2 with the power dissipation split up according to the duty cycle: V DC(Q1) = OUT VIN ( VIN − VOUT V DC(Q2) = 1 − OUT = VIN VIN ) The RDS(ON) required for a given conduction loss can now be calculated by rearranging the relation P = I2R. PMAX( Q1) RDS( ON)Q1 = [DC(Q1)](IMAX2 ) ( VIN )[PMAX( Q1) ] = ( VOUT)(IMAX2 ) In most LTC1530 applications, RDS(ON) is used as the current sensing element.
PAGE 13
LTC1530 U W U U APPLICATIO S I FOR ATIO Table 1. Recommended MOSFETs for LTC1530 Applications PART NO. PACKAGE RDS(ON) AT 25°C (Ω) Siliconix SUD50N03-10 TO-252 0.019 15A at 25°C 10A at 100°C 3200 1.8 175 Siliconix Si4410DY SO-8 0.020 10A at 25°C 8A at 75°C 2700 — 150 MTD20N03HDL DPAK 0.035 20A at 25°C 16A at 100°C 880 1.67 150 FDS6680 SO-8 0.01 11.5A at 25°C 2070 25 150 MTB75N03HDL* D2PAK 0.0075 75A at 25°C 59A at 100°C 4025 1.0 150 IR IRL3103S D2PAK 0.
PAGE 14
LTC1530 U W U U APPLICATIO S I FOR ATIO circuits not employing the current limit function, the current in the inductor may rise above this maximum under short circuit or fault conditions; the inductor should be sized accordingly to withstand this additional current. Inductors with gradual saturation characteristics (example: powdered iron) are often the best choice. Input and Output Capacitors A typical LTC1530 design places significant demands on both the input and the output capacitors.
PAGE 15
LTC1530 U W U U APPLICATIO S I FOR ATIO fLC = VOUT 1 ( 2π LO COUT ) 3 LTC1530 COMP The ESR of the output capacitor and the output capacitor value form a zero at the frequency: 1 (2π)(ESR)(COUT ) 1 (2π)(RC)(CC) and fP = C1 BG CC 1530 F08a The compensation network used with the error amplifier must provide enough phase margin at the 0dB crossover frequency for the overall open-loop transfer function.
PAGE 16
LTC1530 U W U U APPLICATIO S I FOR ATIO Table 3. Suggested Compensation Network for a 5V Input Application Using Multiple Paralleled 1500µF SANYO MV-GX Output Capacitors for 2.5V Output LO (µH) CO (µF) RC (kΩ) CC (µF) C1 (pF) 1 4500 3 0.022 470 1 6000 4 0.022 330 1 9000 6 0.022 220 2.7 4500 8.2 0.022 150 2.7 6000 11 0.01 100 2.7 9000 16 0.01 100 5.6 4500 16 0.01 100 5.6 6000 22 0.01 68 5.6 9000 33 0.
PAGE 17
LTC1530 U W U U APPLICATIO S I FOR ATIO VIN BOLD LINES INDICATE HIGH CURRENT PATHS PVCC 1 + 0.1µF 10µF G1 LTC1530 2 GND 3 4 RC C1 PVCC G2 IFB VOUT IMAX COMP 8 Q1 + CIN 7 LO RIFB 6 VOUT 5 RIMAX + Q2 COUT 0.1µF CC 1530 F09 Figure 9. LTC1530 Layout Diagram PVCC 12V 10µF 2.7k + 0.
PAGE 18
LTC1530 U TYPICAL APPLICATIO S 5V to 1.9V-3.3V Synchronous Buck Converter PVCC Is Generated from Charge Pump VIN 5V MBR0530T1 MBR0530T1 5 4 C1 RC CC + + 2.7k 0.1µF IMAX CIN** 10µF 0.22µF 1 PVCC G1 8 6 Q1* 20Ω COMP IFB LTC1530 7 (SEE TABLE) G2 3 GND VOUT (SEE TABLE) LO† + Q2* VOUT 1.9V TO 3.3V 14A CO (SEE TABLE) 2 * SILICONIX SUD50N03-10 ** 3× SANYO 10MV1200GX OR 3× SANYO OS-CON 6SH330K † COILTRONICS CTX02-13198 (2µH) OR PANASONIC ETQP6F2R5HA PCC-N6 (2.
PAGE 19
LTC1530 U TYPICAL APPLICATIO S LTC1530 3.3V to 1.8V, 14A Application VIN 3.3V 1 + 3.3µF 10µF VIN 2 + GND 3 C1 – LTC1517-5 5 C1+ 4 0.22µF VOUT D2 MBRS120 D1 MBRS120 PVCC + CIN 1500µF ×3 + COUT 1500µF ×4 + 0.1µF 10µF 2.4k 1 5 IMAX C1 100pF PVCC L1 2.5µH 20Ω COMP IFB LTC1530-ADJ 7 G2 RC 13k CC 0.022µF 0.22µF 8 G1 6 4 Q1 SUD50N03 Q2 SUD50N03 3 GND VSENSE R2 1.24k 1% 2 VOUT 1.
PAGE 20
LTC1530 U TYPICAL APPLICATIO S LTC1530 High Efficiency Boost Converter VIN 3.3V C3 1µF 16V R2 47k + C10 1µF 16V C11 470µF 6V R5 0.005Ω 5% L2 2.1µH R4 360Ω C9 0.22µF 16V C12 470µF 6V L1 1µH D3 MBRS140T3 + Q3 IRF7811 + C8 1µF 16V C1 10µF 16V 5 C1– VIN LTC1517-5 4 2 GND C1+ C6 1µF 16V 4 C4 100pF 1 3 1 C2 1µF 16V C7 0.22µF 16V R3 47k IFB COMP G2 LTC1530 G1 R1 10k C14 330µF 10V + + C13 1µF 16V C15 330µF 10V VOUT 5V 6A Q4 IRF7811 VSENSE 7 R7 71.5k 1% 8 3 1530 TA05a R6 23.
PAGE 21
LTC1530 U TYPICAL APPLICATIO S LTC1530 5V to – 5V Synchronous Inverter VIN 5V + CIN R8 560Ω 1/2W R1 2.4k 2.2µF R9 680Ω D2 MBR0530T1 1 C3 10µF 5 PVCC IMAX C4 0.1µF 8 G1 IFB LTC1530-ADJ G2 4 C1 1000pF VSENSE COMP RC 4.7k 6 4 5 Q1 1/2 LTC1693-2 Q3 2N7000 6 R10 330Ω R2 100Ω 3 D5 MBR0530T1 GND + R11 1k L1 2.5µH C5 2.2µF 1 2 CC 0.22µF VOUT –5V 5A Q2 D4 1N4148 7 R7 4.
PAGE 22
LTC1530 U TYPICAL APPLICATIO S LTC1530 Synchronous SEPIC Converter 1,2,3 Q2 P-MOSFET CFLY L1A • 7,8,9 4,5,6 D1 MBR0520 L2 10µH C8 4.7µF + 6 3 VIN SW SHDN GND R8 33k C6 100pF 4 C3 10µF C4 0.1µF 1 R6 2.2M LTC1530-ADJ G2 4 RC 4.7k R7 300k CC 0.22µF C2 10µF + COUT • + 6 5 G1 2 D2 1N4148 R4 1k PVCC IMAX IFB C1 1000pF FB VC C7 3000pF + 5 LT1317 1 C9 4.7µF VOUT 5V 4A R2 10k R5 20Ω R1 2.2k R9 5.6Ω + 10,11,12 Q1 N-MOSFET + R3 3.09k L1B + CIN VOUT + RSENSE 0.
PAGE 23
LTC1530 U PACKAGE DESCRIPTION S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 7 6 5 N N .245 MIN .160 ±.005 1 .030 ±.005 TYP .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) 2 3 N/2 N/2 RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 2 3 4 .053 – .069 (1.346 – 1.752) .004 – .010 (0.101 – 0.254) 0°– 8° TYP .016 – .050 (0.406 – 1.270) NOTE: 1.
PAGE 24
LTC1530 U TYPICAL APPLICATION LTC1530 – 5V to 2.5V, 5A Inverting Polarity Converter (OPTIONAL) GND R8 4.7Ω Z1 1N4742A + CIN 1500µF 6.3V ×3 C5 0.1µF C4 10µF RSENSE 0.02Ω R6 2k + 1 5 PVCC IMAX 4 MBRS130 MBRS130 L1 2.5µH R7 22Ω 6 IFB G1 COMP C8 0.22µF + Q2 8 Q1 LTC1530-ADJ RC 5.6k C1 1000pF CC 0.1µF G2 VSENSE GND 2 VOUT* 2.5V 5A COUT 1500µF 6.3V ×3 Z2 BZX55C6V2 1/2W, 6.2V 7 3 R10 1k Q4 2N3904 R9 10k R1 1.