Part # LM2639 datasheet

Part Manufacturer: National Semiconductor

National Semiconductor

Part Description: LM2639 5-Bit Programmable, High Frequency Multi-phase PWM Controller


Part Details:

LM2639 February 2000 5-Bit LM26395-Bit Programmable, High Frequency Multi-phase PWM Programmable, Controller General Description The LM2639 also provides input under-voltage lock-out withhysteresis and input over-current protection. The LM2639 provides an attractive solution for power sup-plies of high power microprocessors (such as Pentium IITM, Features M IITM, K6TM-2, K6TM-3, etc.) exhibiting ultra fast load tran-sients. Compared to a conventional single-phase supply, an n Ultra fast load transient response LM2639 based multi-phase supply distributes the thermal n Enables all surface-mount-design and electrical loading among components in multiple phases n Selectable 2, 3, 4 phase operation High and greatly reduces the corresponding stress in each com- n Clock frequency from 40 kHz to 10 MHz ponent. The LM2639 can be programmed to control either a n Precision load current sharing 3-phase converter or a 4-phase converter. Phase shift n 5-bit programmable from 3.5V to 1.3V among the phases is 120° in the case of three phase and 90° Frequency with four-phase. Because the power channels are out of n VID code compatible to VRM 8.X specification phase, there can be significant ripple cancellation for both n Output voltage is 2.0V for VID code 11111 the input and output current, resulting in reduced input and n Selectable internal or external clock output capacitor size. Due to the nominal operating fre- n Digital 16-step soft start quency of 2 MHz per phase, the size of the output inductors n Input under-voltage lock-out, over-current protection can be greatly reduced which results in a much faster loadtransient response and a dramatically shrunk output capaci- Applications tor bank. Microprocessor power supplies with all surface Multi-phase mount components can be easily built. n Servers and workstations n High current, ultra-fast transient microprocessors The internal high speed transconductance amplifier guaran-tees good dynamic performance. The output drive voltagescan be adjusted through a resistor divider to control switch-ing loss in the external FETs. The internal master clock frequency of up to 8 MHz is set byan external reference resistor. An external clock of 10 MHzcan also be used to drive the chip to achieve frequency con- PWM trol and multi-chip operation. Pin Configuration Controller 24-Pin Plastic SOIC DS101143-1 Top View See NS Package Number M24B M IITM is a trademark of Cyrix Corporation a wholly owned subsidiary of National Semiconductor Corporation.Pentium IITM is a trademark of Intel Corporation.K6TM is a trademark of Advanced Micro Devices, Inc. © 2000 National Semiconductor Corporation DS101143


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LM2639.pdf Datasheet