SI9117

Si9117 Vishay Siliconix High-Frequency Converter for Telecom Applications FEATURES D D D D On-board high-voltage, 1-W Switching FET Switching Frequencies of Up to 1 MHz Synchronization Capability Easily Compensated Current-Mode Operation D D D D Operates with Input Voltages Up to 200 V 1.8-MHz Error Amplifier Soft-Start Latched SHUTDOWN DESCRIPTION The Si9117 high-efficiency converter for telecom systems running off 48 V is ideal for emerging applications such as interactive video (IV) set-top boxes and microcell base stations, such as those used for Personal Communications Systems (PCS). IV set-top boxes and microcell base stations typically require less than 15 W of power and have access to the analog telephone line power. Both IV set-top boxes and microcell base stations process extremely low-level, modulated analog signals (on the order of mVs), making the frequency and energy content of radiated and conducted noise a major issue. These application circuits are also constrained in terms of available board space and place a premium on minimal footprint. Processing high-frequency, modulated analog signals for video or RF requires receivers with sensitivities in the range of 0.5 to 25 mV. At these levels, noise generated by switchmode power conversion can impair the signal recovery process. Controlling radiated noise is a matter of proper layout and shielding. Controlling conducted noise is a matter of limiting its energy and isolating the conducted energy’s fundamental and harmonic frequencies to bands which will not affect the frequencies of interest. The high-frequency, synchronized switching of the Si9117 enables this design requirement. First, for a given output current, high-frequency switching attenuates output ripple, minimizing conducted energy. Second, synchronizing the high switching frequency to an external frequency allows the fundamental and its harmonics to be moved out of range of the frequency bands of interest. An additional benefit of high-frequency switching is reduced size and cost of the inductor and the output filter capacitance. In addition to these mandatory design considerations, the Si9117 is easy to design with and compensate, and takes a minimum of board area to implement: an important benefit in high-volume/small-package applications such as set-top boxes and microcell base stations. The Si9117 is available in both standard and lead (Pb)-free packages. The combination of an on-board, high-voltage, 1-W switch and a PWM IC with operational input voltage of 200 V allows operation off of the analog telephone line, even with the worst case battery voltage and ringing voltage. Once the converter has started up, a simple bootstrap circuit can provide power to the IC by raising the source voltage of the n-channel, depletion mode, start-up FET above its gate voltage of 9.2 V. This technique lowers system costs, reduces the area required for circuit implementation, and minimizes circuit power consumption. APPLICATIONS CIRCUIT VIN + VOUT 1 2 3 SYNC 4 5 6 7 8 16 15 14 13 12 11 10 9 NC SHUTDOWN Si9117 Document Number: 70027 S-40750—Rev. E, 19-Apr-04 www.vishay.com 1 Si9117 Vishay Siliconix ABSOLUTE MAXIMUM RATINGS Voltages Referenced to −VIN VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 V +VIN (Note: VCC < +VIN + 0.3 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 V Logic Input (SHUTDOWN, SYNC) . . . . . . . . . . . . . . . . −0.3 V to VCC + 0.3 V Linear Inputs (FEEDBACK, SENSE, SOFT-START) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to VCC + 0.3 V HV Pre-Regulator Input Current (continuous) . . . . . . . . . . . . . . . . . . . . . 5 mA Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65 to 150_C Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −40 to 85_C Junction Temperature (TJ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150_C Drain-Source Voltage (TA = 25_) (VDS)a . . . . . . . . . . . . . . . . . . . . . . . . . 200 V Continuous Drain Current (TA = 25_) (ID)a . . . . . . . . . . . . . . . . . . . . . . . 1.0 A Power Dissipation (Package)a 16-Pin SOIC (Y Suffix)b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 mW Thermal Impedance (QJA) 16-Pin SOIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140_C/W Notes a. Device mounted with all leads soldered or welded to PC board, t v 2 sec. b. Derate 7.2 mW/_C above 25_C. RECOMMENDED OPERATING RANGE Voltages Referenced to −VIN VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5 V to 16.5 V +VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 V to 200 V fOSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 kHz to 2 MHz ROSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 kW to 1 MW COSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 pF to 200 pF Linear Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to VCC − 4 V Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to VCC SPECIFICATIONS Test Conditions Unless Specified Parameter Reference OSC Disabled, TA = 25_C Output Voltage Short Circuit Current Load Regulation VR ISREF DVR/DIR OSC Disabled Over Voltage and Temperature Rangesc VREF = −VIN IREF = 0 to −1 mA 3.94 3.88 4.0 4.0 −30 10 4.06 4.12 −5 40 V mA mV Limits Mina Typb Maxa Unit Symbol Oscillator Disabled −VIN = 0 V, VCC = 10 V Oscillator Initial Accuracy Voltage Stabilityc Temperature Coefficientc fOSCd Df/f OSC TC ISYNC(M) ISYNC(S) ROSC = 374 kW , COSC = 200 pF ROSC = 70 kW , COSC = 200 pF ROSC = 70 kW , COSC = 200 pF Df/f = [f(16.5 V) − f(9.5 V)] / f(9.5 V) −40 v TA v 85_C, fOSC = 100 kHz VROSC v 5 V VROSC = VCC "1.0 90 450 100 500 1 200 "3.0 "1 "500 110 550 2 500 kHz % ppm/_C mA nA Sync Output Current (Master Mode) Sync Output Current (Slave Mode) Error Amplifier (COSC = −VIN OSC Disabled) Input BIAS Current Input OFFSET Voltage Open Loop Voltage Gainc Unity Gain Bandwidthc IFB VOS2 AVOL BW IOUT PSRR Source (VFB = 3.5 V, NI = VREF) Sink (VFB = 4.5 V, NI = VREF) 9.5 V v VCC v 16.5 V 1.0 50 65 1.8 VFB = 5 V, NI = VREF