MAX8544EEP+ Maxim Integrated Products, MAX8544EEP+ Datasheet

Page 1

... Storage Servers INPUT 3V TO 13.2V ON OFF OPTIONAL SYNCHRONIZATION ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. Prebias Startup/Monotonic 1% Output Accuracy Ceramic, Polymer, or Electrolytic Capacitors 200kHz to 1MHz Adjustable Frequency 160kHz to 1.2MHz Synchronization ...

Page 2

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP ABSOLUTE MAXIMUM RATINGS IN, EN, CS+, CS- to GND .......................................-0.3V to +14V BST ..........................................................-0.3V to +6V BST to GND ............................................................-0.3V to +20V DL, COMP, ILIM2, SS, SYNCO, ...

Page 3

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP ELECTRICAL CHARACTERISTICS (continued 13.2V 5V 0°C to +85°C, unless otherwise noted. Typical values are BST LX A PARAMETER Current-Limit ...

Page 4

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP ELECTRICAL CHARACTERISTICS (continued 13.2V 5V 0°C to +85°C, unless otherwise noted. Typical values are BST LX A PARAMETER POK ...

Page 5

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP ELECTRICAL CHARACTERISTICS (continued 13.2V 5V -40°C to +85°C, unless otherwise noted.) (Note 2) IN BST LX A PARAMETER CURRENT-SENSE AMPLIFIER Voltage Gain ...

Page 6

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP ELECTRICAL CHARACTERISTICS (continued 13.2V 5V -40°C to +85°C, unless otherwise noted.) (Note 2) IN BST LX A PARAMETER POK Power-OK Threshold POK ...

Page 7

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP (T = +25°C, unless otherwise noted.) A EFFICIENCY vs. LOAD CURRENT WITH 12V INPUT 100 3.3V OUT 2.5V OUT ...

Page 8

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP (T = +25°C, unless otherwise noted.) A MAX8544 STEP-LOAD RESPONSE 7.5A TO 15A TO 7.5A (5A/μs) V OUT I OUT 10μs/div MAX8544 POWER-UP WAVEFORMS OUT V POK ...

Page 9

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP (T = +25°C, unless otherwise noted.) A MAX8544 ENABLE WAVEFORMS OUT V POK I L 2ms/div SHORT CIRCUIT AND RECOVERY OUT ...

Page 10

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP (T = +25°C, unless otherwise noted.) A BODE PLOT, 600kHz, 15A LOAD 0dB 10dB/div 1kHz 10kHz PIN NAME MAX8543 MAX8544 1 2 GND COMP 4 ...

Page 11

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP PIN NAME MAX8543 MAX8544 BST 16 19 FSYNC — 1 ILIM2 — 10 MODE — 11 POK — 20 SYNCO ______________________________________________________________________________________ FUNCTION ...

Page 12

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP V = (10.8V TO 13.2V) IN C12 9 ILIM1 SYNC FSYNC ON OFF GND COMP R2 ...

Page 13

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP Table 1. Suggested Components for Figure 1 DESIGNATION QTY C4A, C4B, C4C C6A, C6B C9, C10 ...

Page 14

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP V = (3V TO 3.6V) IN C12 8 ILIM SYNC FSYNC ON OFF GND COMP R2 ...

Page 15

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP Table 2. Suggested Components for Figure 2 DESIGNATION QTY C4A, C4B, C4C, 4 C4D C5 1 C6A, C6B C9, ...

Page 16

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP Detailed Description DC-DC Converter Control Architecture The MAX8543/MAX8544 step-down controllers use a PWM, current-mode control scheme. An internal transconductance amplifier establishes an integrated error voltage. The heart of the PWM ...

Page 17

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP Use very short, wide traces, about squares (50 mils to 100 mils wide if the MOSFET is 1in from the device) for the gate drive. The dead ...

Page 18

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP TIME Figure 4. Inductor-Current Waveform Switching Frequency and Synchronization The MAX8543/MAX8544 have an adjustable internal oscillator that can be set to any frequency from 200kHz to 1MHz. To set the ...

Page 19

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP A good compromise between size and efficiency is an LIR of 0.3. Once all the parameters are chosen, the inductor value is determined as follows: × − ...

Page 20

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP 2) If the resulting value of R ILIM increase P or choose a low-side MOSFET with a FB lower R . The latter is preferred as it increas- DS(ON) es ...

Page 21

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP MOSFET Selection The MAX8543/MAX8544 drive two or four external, logic-level, n-channel MOSFETs as the circuit switch elements. The key selection parameters are: 1) On-resistance (R ): the lower, the better. ...

Page 22

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP MOSFET Snubber Circuit Fast switching transitions cause ringing because of res- onating circuit parasitic inductance and capacitance at the switching nodes. This high-frequency ringing occurs at LX’s rising and falling ...

Page 23

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP The aluminum electrolytic capacitor is the least expen- sive; however, it has higher ESR. To compensate for this, use a ceramic capacitor in parallel to reduce the switch- ing ripple ...

Page 24

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP zEA × × 2π pEA × × 2π The crossover frequency should be much higher C ...

Page 25

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP pMOD ⎛ ⎞ × × LOAD S π × × ⎜ ESR ⎟ OUT + × ⎝ ⎠ ...

Page 26

Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVP Table 4. Suggested Component Manufacturers MANUFACTURER Central Semiconductor Coilcraft International Rectifier Kamaya Panasonic Sanyo Sumida Taiyo Yuden TDK Vishay/Siliconix Pin Configurations TOP VIEW GND COMP 3 MAX8543 ...

Page 27

... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 27 © 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products ...