ISL6551EVAL1 Intersil, ISL6551EVAL1 Datasheet

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ISL6551EVAL1

Manufacturer Part Number
ISL6551EVAL1
Description
EVALUATION BOARD ISL6551
Manufacturer
Intersil
Datasheets

Specifications of ISL6551EVAL1

Main Purpose
DC/DC, Step Down
Outputs And Type
1, Isolated
Voltage - Output
3.3V
Current - Output
60A
Voltage - Input
36 ~ 75V
Regulator Topology
Buck
Frequency - Switching
470kHz
Board Type
Fully Populated
Utilized Ic / Part
ISL6551
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Power - Output
-
This application note highlights design considerations for a 200W, 470kHz, telecom power supply using Intersil’s ISL6551 ZVS Full-
Bridge Controller and ISL6550 Supervisor And Monitor. The zero-voltage switching technique of the ISL6551 is presented in detail.
A step-by-step design procedure for a 48V-to-3.3V@60A with 88% efficiency converter based on these two chips, incorporating
both ZVS full bridge and current doubler topologies, is described. A few tips for design and debugging are then listed. Finally,
experimental results with discussion gives users a deeper understanding of the performance of the reference design and the
advantages of the ISL6550 and ISL6551.
Introduction
In medium to high power applications with extreme efficiency
requirements, the full-bridge topology is probably the best
choice. Besides great transformer utilization with this
topology, higher efficiency and lower EMI levels are the
major benefits if utilizing circuit parasitics, which include
output capacitance of the bridge FETs, primary capacitance
of the transformer, and leakage inductance, to achieve zero-
voltage transitions (ZVT). In the conventional full bridge
converter, these advantages cannot be realized without
employing a significant amount of soft-switching/resonant
circuitry which adds cost and circuit board real estate.
Intersil’s ISL6551 full-bridge controller implements a unique
control algorithm, rather than the traditional phase-shifted
control technique introduced by TI’s UC3875, to achieve
ZVS with few components. In addition, the ISL6551
integrates additional sophisticated features such as Leading
Edge Blanking, Latching Shutdown Input, Enable Input,
Current Share Support, Fast Short-Circuit Shutdown,
Synchronous Drive Signals, and Power Good Indication that
the UC3875 does not provide. The ISL6551 enables a
complete and sophisticated power supply solution and can
save board space and engineering effort as well as cost.
This application note provides detailed design
considerations of a 200W telecom power supply reference
design employing both Intersil’s ISL6551 full-bridge
controller and ISL6550 Supervisor and Monitor while taking
advantage of both ZVS full-bridge and current doubler
topologies, as shown in Figure 1.
An alternative secondary rectification technique for push-pull
and bridge converters is introduced by Laszlo Balogh in his
paper [2]. This technique offers potential benefits of better
distributed power dissipation in densely packed power
supplies and in medium to high power and/or high output
current applications [2].
This converter is designed to meet the specification of an
industry-standard half brick. Most of the converter circuits
are placed in the central 2.50”x2.45” area and limited within
0.5” height, and all other unnecessary components such as
test point connectors and I/O connectors are placed beyond
this area. To easily modify the evaluation board for a broader
base of applications, additional circuits are designed in and
®
1
200W, 470kHz, Telecom Power Supply Using ISL6551 Full-
Application Note
Bridge Controller and ISL6550 Supervisor and Monitor
1-888-INTERSIL or 321-724-7143
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Abstract
magnetics components are not integrated with the PCB. This
expands the area of the evaluation board when compared to
a standard half-brick design. This DC/DC converter accepts
a wide range input of 36V to 75V and generates a DAC-
adjustable wide range output of 2.64V to 3.63V with
31.918mV step. An ultra high efficiency of 88% at 3.312V
with a fully loaded 60A output has been achieved.
This application note first introduces the unique ZVS
technique of the ISL6551. The Supervisor and Monitor
ISL6550 chip is then briefly introduced. Thereafter, a step-
by-step design procedure for the reference design is
followed, including power train component selection,
component power dissipation calculations, magnetics design
parameter calculations, and control loop design. A few tips
for design and debugging are listed. Finally, experimental
results of the evaluation board are discussed. Term
Definitions, Block Diagram, Schematics, Layout, Bill of
Materials, References, and Preliminary Specifications of the
Reference Design are included at the end of this paper.
Intersil ZVS Full Bridge Controller:
ISL6551
The diagonal bridge switches are turned on together in a
conventional full bridge converter which alternatively places
the input voltage, V
for a period of Ton, as shown in Figure 2. The limiting factor
of achieving optimum efficiency in this circuit is the hard
switching nature of the operation, which causes significant
FIGURE 1. FULL BRIDGE + CURRENT DOUBLER TOPOLOGIES
+
Vin
-
QA
QB
August 2002
|
Intersil (and design) is a registered trademark of Intersil Americas Inc.
QC
QD
+
Vp
-
Copyright © Intersil Americas Inc. 2002. All Rights Reserved
IN
, across the primary of the transformer
T
+
Vs
-
Author: Chun Cheung
Q1
Q2
Lo
AN1002
Vo
Co

Related parts for ISL6551EVAL1

ISL6551EVAL1 Summary of contents

Page 1

... Application Note This application note highlights design considerations for a 200W, 470kHz, telecom power supply using Intersil’s ISL6551 ZVS Full- Bridge Controller and ISL6550 Supervisor And Monitor. The zero-voltage switching technique of the ISL6551 is presented in detail. A step-by-step design procedure for a 48V-to-3.3V@60A with 88% efficiency converter based on these two chips, incorporating both ZVS full bridge and current doubler topologies, is described ...

Page 2

... The ISL6551 is a ZVS full bridge controller that Intersil has designed for medium to high power AC/DC and DC/DC applications with ultra high efficiency requirements. The ...

Page 3

CLOCK UP1 UP2 LOW1 LOW2 VP SYNC1 1 SYNC2 LOW1’ 2 LOW2’ SYNC2 3 SYNC1 T0-T1=LOWER RIGHT-LEG POWER TRANSFER PERIOD T1-T2=UPPER LEFT-TO-RIGHT FREEWHEELING PERIOD T2-T3=Q1-TO-Q2 DEADTIME (FREEWHEELING) T3-T4=LOWER LEFT-LEG RESONANT PERIOD In the above Figure, T0 through ...

Page 4

VS I LO1 I LO2 WORST CASE I Q1 WORST CASE I Q2 WORST CASE I MAG I P WORST CASE SYNC1 1 SYNC2 LOW1’ 2 LOW2’ SYNC2 3 SYNC1 T0-RESDLY T0-T1=LOWER RIGHT-LEG ...

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T0 -->T1, QA-to-QD Power Transfer (Active) Period [Figure ON QC= OFF + Vin ...

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Q1 and Q2 are turned on during the freewheeling time, which could reduce the conduction losses and the reflected output current in the primary. The amount of the load current split into Q1 and Q2 depends on ...

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T4 --> T5, QC-to-QB Power Transfer Period [Figure 10 ON OFF + ...

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... INV_LOW DRIVE ON INV_SYNC DRIVE FIGURE 13. LOWER RIGHT-LEG RESONANT PERIOD Intersil Supervisor and Monitor: ISL6550 The ISL6550 is a precision flexible, VID-code-controlled reference and voltage monitor for high-end microprocessor and memory power supplies. It monitors various input signals, and supervises the systems with its outputs. The ISL6550 saves board space, design time, and system cost ...

Page 9

VREF5 error and external resistor divider error as well as the internal buffer offset. In the reference design, the output voltage can be programmed from 2.64V to 3.63V with 31.918mV step and +/-3% statics error over ...

Page 10

Converter Design This section presents a step-by-step design procedure for a 48V-to-3.3V, 200W, 470kHz with 88% efficiency converter using both ISL6551 and ISL6550 for telecom applications (i.e V =36V-to-75V). The converter is designed with IN secondary-referenced, peak current-mode control, and ...

Page 11

Vsynfet = Io x Rdsonsyn/2 is the channel drop of the synchronous FETs at half of the load (assuming that the output load is split evenly into both synchronous FETs during the freewheeling period), Vomax is the maximum output ...

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ESR and capacitance. dI ∆V • ---- - = ESL ESL dt Vo f(Istep) ∆V ∆V ESL Istep FIGURE 16. TYPICAL TRANSIENT RESPONSE WAVEFORM Thus, ...

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Ib I ∆ Ia CASE – 0 ∆ 2   I • Irms4 ------- - –   • WHERE Ic = ---------------- - ...

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... FET to zero volt before they are turned on. The turn-on losses of the lower FETs can be approximated with EQ. 45. The turn-off losses of primary switches can be minimized with a high speed driver such as Intersil HIP2100. (EQ. 41) Ppriswon (EQ. 42) When the lower FET is turned off, its corresponding upper ...

Page 15

EXPERIMENTAL RESULTS, prior to turn off the synchronous FET, help to achieve ZVT for the synchronous FETs at turn off. To achieve ZVT as discussed in previous lines, the synchronous FET drivers however should have ...

Page 16

Figure 17 shows the block diagram of the overall closed-loop system. PWM ISOLATION + - RAMP CURRENT TRANSFORMER ERROR AMPLIFIER - + FIGURE 17. BLOCK DIAGRAM OF CLOSED-LOOP SYSTEM This peak current mode controlled ...

Page 17

Special Notes for Configuring the ISL6551 The controller can be easily configured using Table 1 in the ISL6551 datasheet. In this section, several things that require the users’ attention are highlighted. For a detailed configuration, please refer to the device ...

Page 18

Heavy copper traces should be connected to the bias pins (VDD, VDDP1, VDDP2) and the ground pins (VSS and PGND) for heat spreading. • The copper ...

Page 19

START will not be latched. The latch can be reset by the PEN signal, which is controlled by the input voltage, the mechanical switch, and the thermal condition of the converter. If latching the converter off ...

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TABLE 2. DESIGN PARAMETER REQUIREMENTS (Continued) PARAMETER CONDITION MAIN TRANSFORMER Imag Lmag=60uH (Limited by Core), Vo=3.63V, Fsw Ipripeak Vin=75V, Vo=3.63V Iprms VIN=75V, Vo=3.63V Isrms Vin=75V, Vo=3.63V N Limited by Core Nmax Vin=36V, Vomax=3.63V, Vmisc=0.3V, Dmaxav=0.85 CURRENT TRANSFORMER Ncs PRIMARY SWITCHES ...

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Thoughts After Design Users can use these thoughts to make some possible improvements of the reference design. 1. The input capacitors (C13-C15) can be replaced with ceramic capacitors with smaller footprints such as TDK SMT1812 C4532X7R2A105M. 2. The output capacitors ...

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... Figure 21, helps eliminate the shoot-through currents through the primary switches during switching transitions. Figures 22 and 23 show the resonant delay and the dead time set at the ISL6551 prior to be processed through pulse transformers (T3 andT5) and bridge drivers (Intersil HIP2100). ...

Page 23

The dead time and the resonant delay, with 2V as the turn-on threshold of primary switches, of one converter is summarized in Table 3. The real delays at the primary switches are shorter than the “delays” set at the ISL6551 ...

Page 24

FIGURE 24. SYNCHRONOUS DRIVE SIGNAL. CHANNEL 1: LOWER DRIVE SIGNAL AT ISL6551; CHANNEL 2: SYNCHRONOUS DRIVE SIGNAL; CHANNEL 3: LOWER DRIVE SIGNAL AT THE LOWER FET Switching Waveforms WINDING VOLTAGE AND CURRENT Figures show the voltage ...

Page 25

FIGURE 27. TRANSFORMER WAVEFORMS =3.3V, AND I =0A (SYN ON). CHANNEL 4: OUT OUT PRIMARY CURRENT (I ); CHANNEL 3: PRIMARY P VOLTAGE (VP); CHANNEL 2: SECONDARY VOLTAGE (VS FIGURE 28. TRANSFORMER WAVEFORMS AT V ...

Page 26

FIGURE 31. RESONANT TRANSITION AT V AND I =37A. CHANNEL 2: V OUT LOWER FET; CHANNEL 3: LOWER GATE DRIVE SIGNAL FIGURE 32. RESONANT TRANSITION (LOST =3.3V, AND I =0A. CHANNEL 2: V OUT OUT VOLTAGE OF ...

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As shown in Figures 35 and 36, the synchronous FETs are zero-voltage switching at turn on, and have negligible switching losses at turn off during the light load. Nevertheless, the two bumps, as shown in Figure 35, are caused by ...

Page 28

ISL6550. For instance, when R40 or R42 is somehow shorted by debris or solder, the output voltage would be programmed (the reference of ISL6550) and the local over-voltage setpoint is also moved up relative to the output ...

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Iout (A) FIGURE 44. EFFICIENCY CURVES FOR V =3.64V @~400 LFM OUT ...

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Output Load (A) FIGURE 47. LOWER FET (Q17) CASE TEMPERATURE ...

Page 31

Input Voltage (V) FIGURE 53. UPPER FET (Q14) CASE TEMPERATURE Input Voltage (V) FIGURE 54. LOWER FET (Q17) CASE TEMPERATURE 95 90 ...

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Input Voltage (V) FIGURE 59. OUTPUT INDUCTOR (L2) CASE TEMPERATURE As shown in the figures above, the current transformer and the main transformer are the hottest components. Without any airflow, their case ...

Page 33

FIGURE 63. TURN ON MASTER (CHANNEL 3 AND CHANNEL 1) FIRST. SLAVE: CHANNEL 4 AND CHANNEL 2 Figures 62 and Figure 63 show the interaction between master and slave units in two different turn-on sequences. When ...

Page 34

FIGURE 67. TRANSIENT RESPONSE FOR 3.3V AT 45A-60A STEP, 1A/us OUT FIGURE 68. TRANSIENT RESPONSE FOR 3.63V AT 0A-15A STEP, 1A/us OUT FIGURE 69. TRANSIENT RESPONSE FOR 3.63V AT 45A-60A STEP, ...

Page 35

PHASE FIGURE 72. PLANT FREQUENCY RESPONSE FOR 3.3V@38A RESISTIVE LOAD. RED-48V, BLUE-75V, AND BLACK-36V 4 1 FIGURE 73. FREQUENCY RESPONSE OF 1) PLANT (Vo/Ve), 2) FEEDBACK COMPENSATION, 3) DIFFERENTIAL AMPLIFIER, AND 4) OPEN LOOP FOR V IN RESISTIVE LOAD. RED-GAIN ...

Page 36

FIGURE 76. OPEN LOOP RESPONSE FOR 2.64V@60A CONSTANT CURRENT LOAD. RED-48V, BLUE- 75V, AND BLACK-36V FIGURE 77. OPEN LOOP RESPONSE FOR 3.3V@60A CONSTANT CURRENT LOAD. RED-48V, BLUE- 75V, AND BLACK-36V FIGURE 78. OPEN LOOP RESPONSE FOR 3.64V@60A CONSTANT CURRENT LOAD. ...

Page 37

In addition to the above loop measurement, the following presents some modeling results using the simplified loop system including the high-frequency correlation term as discussed in the Control Loop Design section on page 16. The feedback compensation and the differential ...

Page 38

Fequency (Hz) FIGURE 87. LOOP RESPONSE FOR 38A “PURE” RESISTIVE LOAD The measured loop and plant responses for 48V input and 3.3V output ...

Page 39

FIGURE 90. OUTPUT VOLTAGE RIPPLE (CHANNEL =75V, V =3.63V, AND I IN OUT FIGURE 91. OUTPUT VOLTAGE RIPPLE (CHANNEL =75V, V =3.63V, AND I IN OUT FIGURE 92. OUTPUT VOLTAGE RIPPLE (CHANNEL 1) AT ...

Page 40

Output Start Up The start up characteristic of the output voltage heavily depends on the load. For a “pure” resistive load or an electronic load with low slew rate (0.01A/us), the output voltage comes up smoothly, as shown in Figures ...

Page 41

FIGURE 100. OUTPUT VOLTAGE STARTUP EXPANSION (CHANNEL =48V =60A, 1A/US ELECTRONIC CONSTANT OUT CURRENT MODE. CHANNEL 2: ERROR VOLTAGE; CHANNEL 3: VCLAMP VOLTAGE; CHANNEL 4: CURRENT RAMP (ISENSE). 100US/DIV. Output Turned Off Characteristic When ...

Page 42

... It turns off the synchronous FETs during the start up at low load conditions. Once the FETs are turned TABLE 8. EQUIPMENT LIST EQUIPMENT DESCRIPTIONS ISl6551EVAL1 Rev. B, #1, #2, #3, & 6653A S/N: 3621A-03425 2. Lamda LQ521 S/N: J 3570 3. XANTREX 100-10 S/N: 72963 4 ...

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... The ZVS technique of the ISL6551 full-bridge controller is presented. The superior performance of the ISL6551, with its BJ17 companions Intersil’s HIP2100 half-bridge driver and ISL6550 Supervisor And Monitor, has been demonstrated in the reference design of a 200W, 470kHz telecom power supply incorporating both full-bridge and current doubler topologies ...

Page 44

TERM DEFINITIONS Cin Input Capacitance Co Output Capacitance Coss Output Capacitance of MOSFET Cp Primary Capacitance of Transformer D Ratio of On-Time Interval of Lower FET to One Clock Period (1/Fclock), Duty Cycle dI Ripple Current thru Each Output Inductor ...

Page 45

TERM DEFINITIONS (Continued) Po Output Power Psynfet Power Dissipation of Synchronous FET Psynfetfr Losses of Syn FET in Freewheeling Period Pupfet Power Dissipation of Upper FET Qg Gate Charge of MOSFET at V Rcs Current Sense Resistor Rdsonpri Rds(on) of ...

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...

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... Inverting Driver OUT OUT SYNN_G 4 5 GND GND C10 C11 MIC4421BM 1u Title SARTN Telecom Power Supply Schematics, 3.3V@60A Size Document Number A ISL6551EVAL1 Date TP1 D Si4842DY VS Reverse D26 R28 Voltage at D26 and D27, at least 40V 0 C64 L2 C 5.6n, 50V R46 DNP 0.8uH SARTN ...

Page 48

... HO LI R30 0 4 R31 HS HI DNP0603 HIP2100IB Q20 TP25 C63 1 DNP0603 C23 Title Telecom Power Supply Schematics, 3.3V@60A Size Document Number A ISL6551EVAL1 Date C13-C15 can be replaced with smaller footprint ceramic caps. D C15 1u Q13 Q14 SUD40N10-25 VS+ TP12 TP13 1 T2 R22 UP2_G 1 TP14 ...

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... ISL6550CIR R42 R43 C29 26.7k 110k SAICRTN R45 10k R47 26.7k Title Telecom Power Supply Schematics, 3.3V@60A SAICRTN Size Document Number A ISL6551EVAL1 Date: Thursday, April 18, 2002 Differential Amp. Output VOPOUT TP26 D31 LED TP27 SAICRTN START ENABLE TP28 R69 100 ...

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... EAO SHARE 11 12 R70 ISL6551IR C45 5.1K TP32 100p C47 470p, NPO, 5% C48 22n, NPO, 5% R74 30.1k Title Telecom Power Supply Schematics, 3.3V@60A SAICRTN TP34 Size Document Number A ISL6551EVAL1 Date SA+12V U1A OUT R48 49.9k C31 LM393D R49 30 R51 20k U1B ...

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... D21 LM393D D22 R91 100k U2B 5 + C55 7 OUT C56 0.1u LM393D SBICRTN Title Telecom Power Supply Schematics, 3.3V@60A Size Document Number A ISL6551EVAL1 Date R83 SB+12V 0 SA+12V C ENABLE R89 100k M8 34.3V Q23 8 Anode NC 33. Cathode Base 6 NC Collector 5 NC ...

Page 52

... OUT C58 DNP 2 - SAICRTN LM393D 2 SAICRTN R99 1M C60 100p SAICRTN U3B OUT 6 - LM393D SAICRTN START D131 3 BAS40-06LT1 ENABLE Title Telecom Power Supply Schematics, 3.3V@60A Size Document Number A ISL6551EVAL1 Date R93 R133 2.67k 2.67k R104 SYNOFF C 0 C59 0. Thursday, April 18, 2002 Sheet ...

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... LittleFuse R451010 Digi-Key S1012-03-ND Various Jumpers for JP1 &JP2 Various Various DT Magnetics 015138 Rev B Micrel Semiconductor MIC4421BM Intersil HIP2100IB Intersil ISL6550CIR Intersil ICL6551IR Texas Instrument TL431AID Infineon IL217AT Burndy KPA8CTP Vishay Siliconix Si4842DY On Semiconductor MMJT9410 Vishay Siliconix SUD40N10-25 On Semiconductor 2N7002LT1 On Semiconductor ...

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Item Quantity Reference 61 8 R6,R7,R12,R13,R14,R25, R28,R30 62 4 R8,R48,R60,R67 R10 65 1 R11 66 2 R77,R17 67 4 R20,R27,R56,R57 68 1 R22 69 4 R23,R24,R26,R33 70 5 R29,R31,R52,R53,R54 71 7 R32,R51,R55,R72,R87,R88, R96 72 3 ...

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... Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use ...

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