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RC5057 Dataheets PDF



Part Number RC5057
Manufacturers Fairchild Semiconductor
Logo Fairchild Semiconductor
Description High Performance Programmable Synchronous DC-DC Controller for Low Voltage Microprocessors
Datasheet RC5057 DatasheetRC5057 Datasheet (PDF)

www.fairchildsemi.com RC5057 High Performance Programmable Synchronous DC-DC Controller for Low Voltage Microprocessors Features • Programmable output from 1.3V to 3.5V using an integrated 5-bit DAC • Remote sense • Active Droop • 85% efficiency typical at full load • Integrated Power Good and Enable/Soft Start functions • Drives N-channel MOSFETs • Overcurrent protection using MOSFET sensing • 16 pin SOIC package • Meets Intel Pentium II & III specifications using minimum number of external co.

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www.fairchildsemi.com RC5057 High Performance Programmable Synchronous DC-DC Controller for Low Voltage Microprocessors Features • Programmable output from 1.3V to 3.5V using an integrated 5-bit DAC • Remote sense • Active Droop • 85% efficiency typical at full load • Integrated Power Good and Enable/Soft Start functions • Drives N-channel MOSFETs • Overcurrent protection using MOSFET sensing • 16 pin SOIC package • Meets Intel Pentium II & III specifications using minimum number of external components Description The RC5057 is a synchronous mode DC-DC controller IC which provides a highly accurate, programmable output voltage for all Pentium II & III CPU applications and other high-performance processors. The RC5057 features remote voltage sensing, adjustable current limit, and active droop for optimal converter transient response. The RC5057 uses a 5-bit D/A converter to program the output voltage from 1.3V to 3.5V. The RC5057 uses a high level of integration to deliver load currents in excess of 16A from a 5V source with minimal external circuitry. Synchronous-mode operation offers optimum efficiency over the entire specified output voltage range. An on-board precision low TC reference achieves tight tolerance voltage regulation without expensive external components, while active droop permits exact tailoring of voltage for the most demanding load transients. The RC5057 also offers integrated functions including Power Good, Output Enable/ Soft Start and current limiting, and is available in a 16 pin SOIC package. Applications • • • • • Power supply for Pentium® II & III VRM for Pentium II & III processor Telecom line cards Routers, switches & hubs Programmable step-down power supply Block Diagram +5V VCCA 5 + 3 RS 10 4 8 VCCP 9 HIDRV +12V +5V OSC + Digital Control + + 7 6 5-Bit DAC 16 15141312 VO LODRV GNDP Power Good 2 PWRGD 1.24V Reference 11 GNDA 1 ENABLE/SS VID0 VID2 VID4 VID1 VID3 Pentium is a registered trademark of Intel Corporation Rev. 1.2.0 RC5057 PRODUCT SPECIFICATION Pin Assignments ENABLE/SS PWRGD IFB VFB VCCA GNDP LODRV VCCP 1 2 3 4 5 6 7 8 RC5057 16 15 14 13 12 11 10 9 VID0 VID1 VID2 VID3 VID4 GNDA SW HIDRV Pin Definitions Pin Number 1 Pin Name ENABLE/SS Pin Function Description Output Enable/Softstart. A logic LOW on this pin will disable the output. An internal current source allows for open collector control. This pin also doubles as soft start. Power Good Flag. An open collector output that will be logic LOW if the output voltage is not within ±12% of the nominal output voltage setpoint. Current Feedback. Pin 3 is used in conjunction with pin 10, as the input for the current feedback control loop. Layout of these traces is critical to system performance. See Application Information for details. Voltage Feedback. Pin 4 is used as the input for the voltage feedback control loop. See Application Information for details regarding correct layout. Analog VCC. Connect to system 5V supply and decouple with a 0.1µF ceramic capacitor. Power Ground. Return pin for high currents flowing in pin 8 (VCCP). Connect to a low impedance ground. Low Side FET Driver. Connect this pin to the gate of an N-channel MOSFET for synchronous operation. The trace from this pin to the MOSFET gate should be <0.5". Power VCC. For both high side and low side FET drivers. Connect to system 12V supply, and decouple with a 4.7µF tantalum and a 0.1µF ceramic capacitor. High Side FET Driver. Connect this pin to the gate of an N-channel MOSFET. The trace from this pin to the MOSFET gate should be <0.5". High side driver source and low side driver drain switching node. Together with IFB pin allows FET sensing for current. Analog Ground. Return path for low power analog circuitry. This pin should be connected to a low impedance system ground plane to minimize ground loops. Voltage Identification Code Inputs. These open collector/TTL compatible inputs will program the output voltage over the ranges specified in Table 2. Pull-up resistors are internal to the controller. 2 3 PWRGD IFB 4 5 6 7 VFB VCCA GNDP LODRV 8 9 10 11 12–16 VCCP HIDRV SW GNDA VID0-4 2 REV. 1.2.0 2/10/00 PRODUCT SPECIFICATION RC5057 Absolute Maximum Ratings Supply Voltage VCCA to GND Supply Voltage VCCP to GND Voltage Identification Code Inputs, VID0-VID4 Junction Temperature, TJ Storage Temperature Lead Soldering Temperature, 10 seconds Power Dissipation, PD Thermal Resistance Junction-to-case, ΘJC 13.5V 15V VCCA 150°C -65 to 150°C 300°C 750mW 105°C/W Recommended Operating Conditions Parameter Supply Voltage VCCA Input Logic HIGH Input Logic LOW Ambient Operating Temperature Output Driver Supply, VCCP 0 11.4 12 Conditions Min. 4.5 2.0 0.8 70 13.2 Typ. 5 Max. 5.25 Units V V V °C V REV. 1.2.0 2/10/00 3 RC5057 PRODUCT SPECIFICATION Electrical Specifications (VCCA = 5V, VCCP = 12V, VOUT = 2.0V, and TA = +25°C using circuit in Figure 1, unless otherwise noted.) The • denotes specifications which apply over the full operating temperat.


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