Si91861 Vishay Siliconix 400-mA Smart Regulator for Network Interface Card FEATURES Single Fixed 3.3-V Output Linear Regulator for 5-V Power Input Auxilliary Input Can Be Bypassed Automatically Switches Between Linear Regulator and Bypass Mode D Linear Regulator: 3.3-V "3% Output at 400-mA Current; 600-mA Peak Output Current D Low Bypass Switch Voltage-Drop: <55-mV at 150 mA D Built-in Short Circuit and Thermal Shutdown Protection D D D D D Low Supply Current D SOIC-8 Package APPLICATIONS D D D D Network Interface Cards (NIC) PCMCIA Cards Cardbus Desktop Computers/Workstations DESCRIPTION The Si91861 provides a constant 3.3-V output with multiple inputs. This function is required in many power interface applications, such as the Network Interface Card (NIC). The Si91861 is offered in small SOIC-8 package with up to 2-W power handling capability. The complete application circuit uses only three external components. The linear regulator steps down from the 5-V supply (5 VIN) to 3.3 V. A 200-mΩ bypass switch is integrated to connect the 3.3-VAUX input to the output. The power drawn priority is 5 VIN > 3.3 VAUX, where the selection is done internally and automatically by the Si91861. The power handling capability is as such as to carry at least 400-mA continuous load current for any power input condition. In order to satisfy the stringent ambient temperature requirements in many applications, the Si91861 is rated for the industrial temperature range of −40_C to 85_C. The Si91861 is available in both standard and lead (Pb)-free packages. FUNCTIONAL BLOCK DIAGRAM Si91861 5 VIN Regulator and Control 3.3 VOUT 3.3 VAUX GND Document Number: 71637 S-40702—Rev. B, 19-Apr-04 www.vishay.com 1 Si91861 Vishay Siliconix ABSOLUTE MAXIMUM RATINGS Pin 2, 4 Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to 6 V Linear Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 600 mA Bypass Switch Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 600 mA Maximum Junction Temperature, TJ(max) . . . . . . . . . . . . . . . . . . . . . . . . 150_C Storage Temperature, TSTG . . . . . . . . . . . . . . . . . . . . . . . . . . −55_C to 150_C ESD (Human Body Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kV Package Power Dissipationb PD . . . . . . . . . . . . . . . . . . . . . . . . 2W (internally limited via thermal shutdown) Thermal Impedance (JA)a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.5_C/W Notes a. Device mounted with all leads soldered or welded to PC board. b. Derate 16 mW/_C above TA = 25_C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. RECOMMENDED OPERATING RANGE 5-VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 V to 5.5 V 3.3 VOUT Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 mA to 400 mA 3.3-VAUX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 V to 3.6 V Operating Ambient Temperature, TA . . . . . . . . . . . . . . . . . . . . −40_C to 85_C SPECIFICATIONS Test Conditions Unless Otherwise Specified Parameter Limits −40 to 85_C Symbol 5 VIN = 5 V, V 3.3 3 3 VAUX = 3 3.3 3V IOUT = 1 mA, CIN = 4.7 F, COUT = 2.2 F Tempa Minb VO(reg) 0 mA < IOUT < 400 mA, 5 VIN u 4.5 V Full 3.201 Typc Maxb Unit Regulator Mode Output Voltage (Regulator) 5 VIN Select Ground Pin Current In Regulator Moded Rising Edge of Hysteresis IGND 3.3 3.399 Threshold Full 4.30 4.475 Hysteresis Full 230 IO = 0 mA Full 0.3 0.8 Full 0.7 1.6 Full IO tPW = 2 ms Output Noise Voltage (Regulator) eN BW = 50 Hz to100 kHz, IOUT = 150 mA Ripple pp Rejection j (Regulator) ( g ) 3.3 3 3 VOUT VIN Room 300 1 kHz Room 60 10 kHz Room 40 100 kHz Room 30 IOUT = 150 mA mA 600 Dynamic Line Regulation VO(line) VIN = 4.5 V @@ 5.5 V tR/tF = 2 s, IOUT = 150 mA Room 10 Dynamic Load Regulation VO(load) IOUT: 1 mA to 150 mA, tR/tF = 2 s Room 20 VOUT Turn-On-Time mV IO = 400 mA Peak Output Current (Regulator) V tON Room 15 Thermal Shutdown Junction Temperature TJ(sd) Full 165 Thermal Hysteresis THYST Full 20 Short Circuit Current ISC 3.3 VOUT = 0 V Room 900 Vrms dB mV s _C C mA Bypass Mode (5 VIN = GND) Output Voltage VO(BP) 0 mA < IOUT < 150 mA Full Bypass Switch On-Resistance rDS(on) 3.0 V v VAUX v 3.6 V Full 0.2 0.35 IGND 0 mA < IOUT < 400 mA Full 200 400 A Ground Currentd 3.247 V Notes a. Room = 25_C, Full = −40 to 85_C. b. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum. c. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. Typical values at 25_C ambient. d. Ground pin current includes the IC supply current and the current to drive the linear regulator or bypass switch. www.vishay.com 2 Document Number: 71637 S-40702—Rev. B, 19-Apr-04 Si91861 Vishay Siliconix TIMING WAVEFORMS 5V tON 5 VIN 0.95 VO(reg) 3.3 VOUT FIGURE 1. Timing Diagram PIN CONFIGURATION SO-8 N.C. 1 8 GND 5 VIN 2 7 GND 3.3 VOUT 3 6 GND 3.3 VAUX 4 5 GND Top View PIN DESCRIPTION Pin Number Document Number: 71637 S-40702—Rev. B, 19-Apr-04 Name Function 1 N.C. Not connected. No effect to device operation 2 5 VIN Power input for the Regulator 3 3.3 VOUT Output 3.3 V 4 3.3 VAUX Power input for the bypass function 5, 6, 7, 8 GND Ground www.vishay.com 3 Si91861 Vishay Siliconix ORDERING INFORMATION Part Number Temperature Range Package Si91861DY-T1 Si91861DY-T1—E3 Tape and Reel −40 to 85_C Si91861DY Bulk Eval Kit Temperature Range Board Type Si91861DB −40 to 85_C Surface Mount TYPICAL CHARACTERISTICS 1.0 Ground Current vs Temperature (5 VIN) Ground Current vs Input Voltage (5 VIN) 1.0 IOUT = 0 IOUT = 600 mA IOUT = 400 mA 0.6 Ground Current (mA) Ground Current (mA) 3.3 VAUX = 0 V 0.8 0.8 IOUT = 200 mA 0.4 IOUT = 0 mA 0.6 0.4 0.2 0.2 5 VIN = 5 V 0.0 −40 0.0 −20 0 20 40 Temperature 0.35 60 80 0 100 ON-Resistance vs 3.3 VAUX Input Voltage 0.8 Ground Current (mA) Resistance (Ω) 85_C 0.20 25_C −40_C 0.15 3.1 3.2 3.3 3.4 3.3 VAUX Input Voltage (V) 4 3 4 5 6 Ground Current vs 3.3 VAUX Input Voltage 0.6 0.25 www.vishay.com 2 Input Voltage (V) 0.30 0.10 3.0 1 (oC) 3.5 3.6 5 VIN 5 V 0.4 0.2 0.0 0.0 5 VIN 0 V 0.6 1.2 1.8 2.4 3.0 3.6 3.3 VAUX Input Voltage (V) Document Number: 71637 S-40702—Rev. B, 19-Apr-04 Si91861 Vishay Siliconix TYPICAL WAVEFORMS Load Transient Response-1 VOUT = 10 mV/div Load Transient Response-2 VOUT = 10 mV/div IOUT = 100 mA/div IOUT = 100 mA/div Input = 5 VIN IOUT = 1 to 150 mA trise = 2 sec Input = 5 VIN IOUT = 150 to 1 mA tFALL= 2 sec M 5.00 s Load Transient Response-3 Load Transient Response-4 VOUT = 50 mV/div VOUT = 50 mV/div IOUT = 200 mA/div IOUT = 200 mA/div Input = 5 VIN IOUT = 0 to 400 mA trise = 2 sec M 5.00 s M 5.00 s Input = 5 VIN IOUT = 400 to 0 mA tFALL = 2 sec 5-VIN Power Up M 5.00 s 5-VIN Power Down 3.3 VOUT (100 mV/div) 3.3 VOUT (100 mV/div) 5 VIN 500 mV/div (offset = 4.3 V) 5 VIN 500 mV/div (offset = 4.2 V) 3.3 VAUX = 0 V IOUT = 400 mA Document Number: 71637 S-40702—Rev. B, 19-Apr-04 M 5.00 s 3.3 VAUX = 0 V IOUT = 400 mA M 5.00 s www.vishay.com 5 Si91861 Vishay Siliconix TYPICAL WAVEFORMS 5 VIN Power Down (3.3 VAUX = 3.3 V) 3.3 VAUX 200 mV/div (offset = 3.3 V) 5 VIN Power Up (3.3 VAUX = 3.3 V) 3.3 VAUX 200 mV/div (offset = 3.3 V) 3.3 VOUT (100 mV/div) 3.3 VOUT (100 mV/div) 5 VIN 500 mV/div (offset = 4.2 V) 5 VIN 500 mV/div (offset = 4.3 V) 3.3 VAUX = 3.3 V IOUT = 400 mA 3.3 VAUX = 3.3 V IOUT = 400 mA M 5.00 s Line Transient −1 (5 VIN) M 5.00 s Line Transient −2 (5 VIN ) 5 VIN (1 V/div) 5 VIN (2 V/div) 3.3 VOUT (10 mV/div) 3.3 VOUT (10 mV/div) 5 VIN = 4.5 to 5.5 V IOUT = 150 mA TRISE = 5 µsec 5 VIN = 5.5 to 4.5 V IOUT = 150 mA TTALL = 5 µsec M 5.00 s M 5.00 s Power Supply Ripple Rejection vs. Frequency 0 5 VIN = 5.0 V) ILOAD = 150 mA −10 PSRR (dB) −20 −30 −40 −50 −60 −70 −80 1 10 100 1K 10 K 100 K 1M Frequency (Hz) www.vishay.com 6 Document Number: 71637 S-40702—Rev. B, 19-Apr-04 Si91861 Vishay Siliconix BLOCK DIAGRAMS AND TYPICAL APPLICATION CIRCUIT Si91861 2 5 VIN 3 4.7 µF 3.3 VOUT 2.2 µF 5-VIN Regulator Driver 4 3.3 VAUX 4.7 µF Logic Control 5, 6 7, 8 DETAIL DESCRIPTION During normal operation, the 5-VIN input powers the fixed 3.3-V output (3.3 VOUT) through an internal linear regulator. If 5 VIN falls below 4.07 V, the output (3.3 VOUT) is powered from 3.3-VAUX input. The power drawn sequence is from 5 VIN, then 3.3 VAUX. The device prevents reverse current from flowing from the output to any unbiased or low voltage input. Linear Regulator Mode The output is regulated at 3.3 V when the 5-VIN pin is more than 4.30 V. The linear regulator will regulate the output until the 5-VIN pin fall below 4.07 V. Bypass Mode Thermal and Over−current Protection Thermal protection limits total power dissipation in the device. It safeguards the device in the event of fault conditions. When the junction temperature exceeds 165_C, the device turns off. The device turns back on once its junction temperature cools down by approximately 20_C. The device has overcurrent protection (typically at 900 mA) when it operates in linear regulator mode. A continuous short at output pin (3.3 VOUT) will result in a pulsed output as the thermal protection circuitry cycles the device on and off. For continuous operation, do not exceed the junction rating of 150_C. In bypass mode, the device is not current limited. When the 5-VIN pin falls below 4.07 V, the output is powered by 3.3 VAUX through a 0.2- internal switch. Document Number: 71637 S-40702—Rev. B, 19-Apr-04 www.vishay.com 7