SI91861

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: 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. 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 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 (qJA)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-VAUX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 V to 3.6 V 3.3 VOUT Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 mA to 400 mA Operating Ambient Temperature, TA . . . . . . . . . . . . . . . . . . . . −40_C to 85_C SPECIFICATIONS Test Conditions Unless Otherwise Specified Parameter Regulator Mode Output Voltage (Regulator) 5 VIN Select Ground Pin Current In Regulator Moded Peak Output Current (Regulator) Output Noise Voltage (Regulator) IGND IO eN D3 3 VOUT/ 3.3 D5 VIN DVO(line) DVO(load) tON TJ(sd) THYST ISC 3.3 VOUT = 0 V VO(reg) 0 mA < IOUT < 400 mA, 5 VIN u 4.5 V Rising Edge of Hysteresis IO = 0 mA IO = 400 mA tPW = 2 ms BW = 50 Hz to100 kHz, IOUT = 150 mA 1 kHz Ripple Rejection (Regulator) pp j (g ) IOUT = 150 mA 10 kHz 100 kHz VIN = 4.5 V @@ 5.5 V tR/tF = 2 ms, IOUT = 150 mA IOUT: 1 mA to 150 mA, tR/tF = 2 ms Threshold Hysteresis Full Full Full Full Full Full Room Room Room Room Room Room Room Full Full Room 600 300 60 40 30 10 20 15 165 20 900 mA ms _C mV dB mVrms 3.201 3.3 4.30 230 0.3 0.7 0.8 1.6 mA 3.399 4.475 V mV Limits −40 to 85_C Symbol 5 VIN = 5 V, 3.3 VAUX = 3.3 V 33 3 IOUT = 1 mA, CIN = 4.7 mF, COUT = 2.2 mF Tempa Minb Typc Maxb Unit Dynamic Line Regulation Dynamic Load Regulation VOUT Turn-On-Time Thermal Shutdown Junction Temperature Thermal Hysteresis Short Circuit Current Bypass Mode (5 VIN = GND) Output Voltage Bypass Switch On-Resistance Ground Currentd VO(BP) rDS(on) IGND 0 mA < IOUT < 150 mA 3.0 V v VAUX v 3.6 V 0 mA < IOUT < 400 mA Full Full Full 3.247 0.2 200 0.35 400 V W mA 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 Document Number: 71637 S-40702—Rev. B, 19-Apr-04 2 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. 5 VIN 3.3 VOUT 3.3 VAUX 1 2 3 4 Top View 8 7 6 5 GND GND GND GND PIN DESCRIPTION Pin Number 1 2 3 4 5, 6, 7, 8 Name N.C. 5 VIN 3.3 VOUT 3.3 VAUX GND Function Not connected. No effect to device operation Power input for the Regulator Output 3.3 V Power input for the bypass function Ground Document Number: 71637 S-40702—Rev. B, 19-Apr-04 www.vishay.com 3 Si91861 Vishay Siliconix ORDERING INFORMATION Part Number Si91861DY-T1 Si91861DY-T1—E3 Si91861DY −40 to 85_C Temperature Range Package Tape and Reel Bulk Eval Kit Si91861DB Temperature Range −40 to 85_C Board Type Surface Mount TYPICAL CHARACTERISTICS 1.0 Ground Current vs Temperature (5 VIN) IOUT = 600 mA 1.0 Ground Current vs Input Voltage (5 VIN) IOUT = 0 0.8 Ground Current (mA) Ground Current (mA) IOUT = 400 mA 0.6 IOUT = 200 mA 0.8 3.3 VAUX = 0 V 0.6 0.4 IOUT = 0 mA 0.4 0.2 5 VIN = 5 V 0.0 −40 0.2 0.0 −20 0 20 40 (oC) 60 80 100 0 1 2 3 Input Voltage (V) 4 5 6 Temperature 0.35 ON-Resistance vs 3.3 VAUX Input Voltage 0.8 Ground Current vs 3.3 VAUX Input Voltage 0.30 Ground Current (mA) 0.6 Resistance (Ω) 0.25 85_C 25_C −40_C 0.4 5 VIN = 5 V 0.20 0.15 0.2 5 VIN =0 V 0.10 3.0 3.1 3.2 3.3 3.4 3.5 3.6 0.0 0.0 0.6 1.2 1.8 2.4 3.0 3.6 3.3 VAUX Input Voltage (V) 3.3 VAUX Input Voltage (V) www.vishay.com 4 Document Number: 71637 S-40702—Rev. B, 19-Apr-04 Si91861 Vishay Siliconix TYPICAL WAVEFORMS Load Transient Response-1 Load Transient Response-2 VOUT = 10 mV/div VOUT = 10 mV/div IOUT = 100 mA/div IOUT = 100 mA/div Input = 5 VIN IOUT = 1 to 150 mA trise = 2 msec M 5.00 ms Input = 5 VIN IOUT = 150 to 1 mA tFALL= 2 msec M 5.00 ms 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 msec M 5.00 ms Input = 5 VIN IOUT = 400 to 0 mA tFALL = 2 msec M 5.00 ms 5-VIN Power Up 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 M 5.00 ms 3.3 VAUX = 0 V IOUT = 400 mA M 5.00 ms Document Number: 71637 S-40702—Rev. B, 19-Apr-04 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) 3.3 VAUX 200 mV/div (offset = 3.3 V) 5 VIN Power Up (3.3 VAUX = 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 M 5.00 ms 3.3 VAUX = 3.3 V IOUT = 400 mA M 5.00 ms Line Transient −1 (5 VIN) 5 VIN (1 V/div) Line Transient −2 (5 VIN ) 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 M 5.00 ms 5 VIN = 5.5 to 4.5 V IOUT = 150 mA TTALL = 5 µsec M 5.00 ms Power Supply Ripple Rejection vs. Frequency 0 −10 −20 PSRR (dB) −30 −40 −50 −60 −70 −80 1 10 100 1K Frequency (Hz) www.vishay.com Document Number: 71637 S-40702—Rev. B, 19-Apr-04 10 K 100 K 1M 5 VIN = 5.0 V) ILOAD = 150 mA 6 Si91861 Vishay Siliconix BLOCK DIAGRAMS AND TYPICAL APPLICATION CIRCUIT Si91861 5 VIN 4.7 µF 2 3 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 When the 5-VIN pin falls below 4.07 V, the output is powered by 3.3 VAUX through a 0.2-W internal switch. 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. Document Number: 71637 S-40702—Rev. B, 19-Apr-04 www.vishay.com 7