End of Life. Last Available Purchase Date is -Dec-20 Si92 High-Voltage, Non-Isolated Buck-Boost Converter for ISDN Digital Phones FEATURES Fixed -V or.-v Output Integrated Floating Feedback Amplifier On-Chip 70-V,.- N-Channel MOSFET Switch Integrated High Voltage Start-Up Circuit, with Regulator 0-V to 0-V Input Voltage Range 9-kHz PWM Operation Integrated Soft-Start and Oscillator High Efficiency Over Full Load Range Under Voltage Lockout Current Mode Control Hiccup Mode Short Circuit Protection Thermal Shutdown SOIC-8 Narrow-Body Package DESCRIPTION The Si92 simplifies the 8-V to -V or.-v converter design for ISDN application by integrating the floating feedback error amplifier providing direct output voltage regulation. This approach eliminates the need for an external shunt regulator. The Si92 also integrates a high voltage depletion mode MOSFET which allows the converter to be powered directly from the high input bus voltage without requiring an external start-up circuit. Combined with simple magnetic design due to its non-isolated topology, the Si92 provides a one-chip solution for complete ISDN power supply. In order to reduce external component count, the Si92 has a fully integrated 9-kHz oscillator and soft-start circuit. The Si92 is available in both standard and lead (Pb)-free SOIC-8 pin packages, and is offered in either -V or.-v fixed output options (Si92DY- or Si92DY-, respectively). In order to satisfy the stringent ambient temperature requirements in many applications, the Si92 is rated to the industrial temperature range of 0 C to 8 C. FUNCTIONAL BLOCK DIAGRAM Regulator Reference Generator BYPASS Control L X V/00 ma or. V/00 ma COMP C S 8 V
ABSOLUTE MAXIMUM RATINGS (ALL VOLTAGES REFERENCED TO = 0 V)...................................................... V V CS..................................... 0. V to 0. V.................................................2 V I LX (peak current )............................................. A........................................................ V Bypass, CS.............................. 0. V to 0. V (V LX V CS ) internal power MOSFET............................ 70 V Storage Temperature.................................. to 0 C Operating Junction Temperature.............................. 0 C Power Dissipation (Package) a 8-Pin SOIC (Y Suffix) b.......................................2 W Thermal Impedance ( JA ) a 8-Pin SOIC............................................. 00 C/W Notes a. Device mounted with all leads soldered or welded to PC board. b. Derate 0 mw/ C above 2 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 (ALL VOLTAGES REFERENCED TO = 0 V).............................................. 0 V to 0 V (internally regulated).............................. 8. V (externally supplied)................ 9. V to 2.0 V Digital Inputs........................................... 0 V to RECOMMENDED EXTERNAL COMPONENTS ( SEE TYPICAL APPLICATIONS CIRCUIT ) L = 8 H, C OUT = 220 F //, CIN = F, C BYPASS =, C VCC = F, R SENSE = 0.2, 0. W SPECIFICATIONS a (All Voltages Are With Respect To Unless Otherwise Specified) Parameter Symbol Output Voltage (with respect to = 0 V) -V Converter.-V Converter Line Regulation (with respect to = 0 V) Test Conditions (Internally Regulated) Unless Otherwise Specified Limits 0 to 8 C = 0 to 0 V Temp b Min c Typ d Max c Unit 0 ma <I LOAD < 20 ma Full.80.00.20 Full.7.0. Line Regulation 0 V 0 V Full % (Internal Regulator) Bias Voltage Full 7. 8. 9. V UVLO Under Voltage Lockout Turn-On Full. 7. 8.7 Hysteresis V Room 0. Soft-Start Error Amplifier Start-Up Current I SS = 0 V Room 0 A Oscillator Switching Frequency f OSC Room 80 9 0 khz Error Amplifier Transconductance gm Room 0 20 umho Clamp Voltage V CL Internal Error Amplifier Output Clamp Voltage Current Limit Room. V Threshold Voltage V CS Full 0.7 0.7 0.77 V MOSFET Switch N-Channel MOSFET r DS(on) Room. 2. V V 2
SPECIFICATIONS a (All Voltages Are With Respect To Unless Otherwise Specified) Supply Parameter Supply Current (Internally Regulater) Supply Current (External Applied) Symbol Test Conditions (Internally Regulated) Unless Otherwise Specified Limits 0 to 8 C = 0 to 0 V Temp b Min c Typ d Max c Unit I to Full.2. I CC to 0 V; >20 V Full. 2.0 ma supply Current I OUT to Full 0.2 0. Start-Up Current I START = 0 V Full 0 Thermal Shutdown Thermal Shutdown Temperature T OTP 70 Thermal Hysteresis T HYS 2 Efficiency Efficiency 00-mA Output, = 8 V Notes a. Refer to PROCESS OPTION FLOWCHART for additional information. b. Room = 2 C, Full = as determined by the operating temperature suffix. c. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum. d. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. V Room 77. V Room 7 C % DETAILED BLOCK DIAGRAM R* 0 A 2 A COMP GM. V H Soft Start 7 R2* V REF.2 V. V Low Side Error Amp 0. V L PWM Hiccup Discharge Mode OSC 0% Max. Duty Cycle R Q OTP V IN 8 L X S BYPASS Bias/ Reference Circuit 0.7 V OCL 0.-V Hysteresis CS 2 8. V *R and R2 are internal voltage setting resistors used to set output voltage to fixed. V or V.
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 2 C UNLESS NOTED). -V vs. Temperature..-V vs. Temperature.0.0.0. (V) VOUT (V).00 VOUT.0.9.2.90.20.8. 0 20 0 20 0 0 80 00 0 20 0 20 0 0 80 00 Temperature ( C) Temperature ( C) 2. r DS(on) vs. Temperature 0 Frequency vs. Temperature r DS(on) On-Resistance ( ) 2.0..0 Frequency (khz) 00 9 90 0. 8 0 20 0 20 0 0 80 00 0 20 0 20 0 0 80 00 Temperature ( C) Temperature ( C). Supply Current vs. ) Supply Current (I..2 8 C 2 C 0 C..0 0 0 0 0 20 0 (V)
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 2 C UNLESS NOTED) 90 Output Load vs. Efficiency (Si92DY-) No Winding 90 Output Load vs. Efficiency (Si92DY-) No Winding 80 V IN = 0 V 80 0 V IN 70 70 Efficiency (%) 0 0 0 V IN = 8 V V IN = 0 V Efficiency (%) 0 0 0 8 V IN 0 V IN 0 0 20 20 0 0 0 0 00 000 I OUT (ma) 0 0 00 000 I OUT (ma) 90 80 Output Load vs. Efficiency (Si92DY-) With Winding = 0 V 90 80 Output Load vs. Efficiency (Si92DY-) With Winding 0 V IN 8 V IN 70 70 Efficiency (%) 0 0 0 0 = 8 V = 0 V Efficiency (%) 0 0 0 0 0 V IN 20 20 0 0 0 0 00 000 I OUT (ma) 0 0 00 000 I OUT (ma)
PIN CONFIGURATION AND ORDERING INFORMATION SOIC-8 ORDERING INFORMATION Part Number Temperature Range Package CS BYPASS COMP 2 Si92 Top View 8 7 L X Si92DY--T Si92DY--T E Si92DY--T Si92DY--T E Si92DY- Si92DY- 0 to 8 C Tape and Reel Bulk Eval Kit Temperature Range Board Type Si92DB- Si92DB- 0 to 70 C Surface Mount and Thru-Hole PIN DESCRIPTION Pin Number Name Function CS Current sense pin to detect the inductor current for current mode control and over current protection 2 Negative supply voltage (0 V to 0 V) BYPASS.-V bandgap reference. Decouple with capacitor. COMP Compensation node to stabilize the converter Output voltage feedback connected to the PWM summing comparator Low impedance system ground Internally generated supply voltage for the internal circuit and MOSFET drive circuit. Decouple with an external 7 bypass capacitor. 8 L X Inductor connection node DETAILED DESCRIPTION Start-Up The UVLO circuit prevents the internal circuits from turning on if VCC is less than 7. V (typical) above the negative supply voltage at pin. With a typical hysteresis of 0. V, the controller is continuously powered on until the voltage drops below 7.0 V. This hysteresis prevents the converter from oscillating during the start-up phase and unintentionally locking up the system. Once ( ) exceeds the UVLO threshold the internal reference, oscillator, and soft-start circuits are enabled. Soft-Start The Si92 has an on-chip soft-start circuit which utilizes the error amplifier external compensation network to ramp the output NMOS transistor current limit which, in turn, allows the output voltage to rise gradually without excessive overshoot. The soft-start circuit is enable once the voltage exceeds the UVLO threshold. For the recommended frequency compensation components (see Typical Application Circuit) the soft-start time is approximately 0 ms. Oscillator The oscillator is designed to operate at a nominal frequency of 9 khz with no external components. The 9-kHz operating frequency allows the converter to operate in PWM mode during the full load condition even though the duty cycle is very low. The 9kHz switching frequency also allows the converter to operate at optimal efficiency without a large output inductor and capacitor. PWM Mode and Current Limit The Si92 is a current-mode converter designed to operate in PWM mode. It features pulse-by-pulse peak current limiting such that when the peak current sensed voltage on the CS pin is greater than 0.7 V the switch is turned off for the remainder of the clock cycle.
DETAILED DESCRIPTION Bypass The bypass voltage of the Si92 is set at a particular positive reference relative to the pin. The bypass voltage is used to set an accurate voltage and bias current for the on-chip oscillator and soft-start circuits. The 0.- F ceramic decoupling capacitor is recommended between the bypass and. No other components should be connected to this pin. Error Amplifier With a 8-V bus voltage, the converter is referenced to the 8-V ( ) node as its system ground. However, the -V or.-v output is referenced to the pin, which is normally connected to 0 V. To regulate this output voltage, the Si92 has an on-chip error amplifier which continuously monitors the output voltage and compares it to a reference voltage. This difference signal is level-shifted to the low side circuit to control the power switch duty-cycle and hence the regulation of the output voltage. Frequency compensation for the error amplifier is achieved by connecting an external network between the COMP pin and the pin. Regulator is an internally generated bias supply voltage which should be externally bypassed with a 0.- F capacitor connected to the negative supply voltage,. No load current should be drawn from the pin. may be supplied from an external source of 9.-V to 2-V referenced to. In this configuration, the internal regulator is disabled when the receives 9.-V, or greater, above. Thermal Shutdown The Si92 also includes thermal shutdown which shuts down the device when junction temperature exceeds 70 C due to over heating. In thermal shutdown once the die temperature cools to below C the regulator is enabled. If the die temperature is excessive due to high package power dissipation the regulator s thermal circuit will continue to pulse the regulator on and off. This is called thermal cycling. Hiccup Mode Short Circuit Protection In addition to the thermal shutdown and the cycle-by-cycle current limiting features already described, the Si92 has a built-in hiccup mode timer to handle a continuous output short-circuit and to automatically restart the device when the short-circuit is removed. If an output short-circuit occurs, the device immediately enters a cycle-by-cycle current limiting mode. As long as the thermal shutdown is not activated then the Si92 automatically determines whether the internal hiccup timer should be started by monitoring the COMP pin. If V COMP exceeds an upper threshold voltage (approximately. V) the timer is started and the external network at the COMP pin is discharged by an internal 2- A current sink until V COMP reaches approximately. V. (Note: all voltages are with respect to ). At this point, the circuit reverts to the normal soft-start mode, whereby the COMP network is charged by its internal soft-start 0- A current source and the circuit will attempt to start up in the normal manner. However, if the output short circuit is still present, the converter will again enter the cycle-by-cycle current limiting mode until the COMP pin voltage reaches. V, whereupon this cycle repeats until the short circuit is removed. The duty cycle imposed by the hiccup timer allows the Si92 to handle continuous short-circuit without damage as long as the recommended component values shown in the Typical Application Circuit are used. MOSFET Switch The low-side n-channel MOSFET switch is integrated to provide optimum performance and to minimize the overall converter size. The typical.- r DS(on) of the MOSFET allows the converter to deliver up to 2 W of output power. 7
TYPICAL APPLICATION CIRCUIT L 8 H 220 F C2 * C F 80 V C C* C F C 7 2 BYPASS L X COMP CS Si92DY- or Si92DY- 8 0MQ00N R 0.2 / 2 W 80 pf C7 V/00 ma or. V/00 ma R2 7 k (27 k for Si92DY-) C8 0 to 0 V FIGURE. Typical Applications Circuit *Optional Silk Screen T C F 80 V C2* 2 CS BYPASS COMP COIL 8 7 8 H Np Ns D2 BAS2 C7 220 F 0 V D 0MQ00N C8* V @ 00 ma R 0.2 / 2 W C C 80 pf C Si92DY- C F R2 7 k (27 k for Si92DY-) *Optional V IN 0 to 0 V FIGURE 2. Si92 Application with External Vcc Through Winding 8
Package Information SOIC (NARROW): 8-LEAD JEDEC Part Number: MS-02 8 7 E H 2 S D A 0.2 mm (Gage Plane) h x C All Leads e B A L q 0.0 mm 0.00" MILLIMETERS INCHES DIM Min Max Min Max A..7 0.0 0.09 A 0.0 0.20 0.00 0.008 B 0. 0. 0.0 0.020 C 0.9 0.2 0.007 0.00 D.80.00 0.89 0.9 E.80.00 0.0 0.7 e.27 BSC 0.00 BSC H.80.20 0.228 0.2 h 0.2 0.0 0.00 0.020 L 0.0 0.9 0.020 0.07 q 0 8 0 8 S 0. 0. 0.08 0.02 ECN: C-027-Rev. I, -Sep-0 DWG: 98 Document Number: 792 -Sep-0
Legal Disclaimer Notice Vishay Disclaimer ALL PRODUCT, PRODUCT SPECIFICATIONS AND DATA ARE SUBJECT TO CHANGE WITHOUT NOTICE TO IMPROVE RELIABILITY, FUNCTION OR DESIGN OR OTHERWISE. Vishay Intertechnology, Inc., its affiliates, agents, and employees, and all persons acting on its or their behalf (collectively, Vishay ), disclaim any and all liability for any errors, inaccuracies or incompleteness contained in any datasheet or in any other disclosure relating to any product. Vishay makes no warranty, representation or guarantee regarding the suitability of the products for any particular purpose or the continuing production of any product. To the maximum extent permitted by applicable law, Vishay disclaims (i) any and all liability arising out of the application or use of any product, (ii) any and all liability, including without limitation special, consequential or incidental damages, and (iii) any and all implied warranties, including warranties of fitness for particular purpose, non-infringement and merchantability. Statements regarding the suitability of products for certain types of applications are based on Vishay s knowledge of typical requirements that are often placed on Vishay products in generic applications. Such statements are not binding statements about the suitability of products for a particular application. It is the customer s responsibility to validate that a particular product with the properties described in the product specification is suitable for use in a particular application. Parameters provided in datasheets and / or specifications may vary in different applications and performance may vary over time. All operating parameters, including typical parameters, must be validated for each customer application by the customer s technical experts. Product specifications do not expand or otherwise modify Vishay s terms and conditions of purchase, including but not limited to the warranty expressed therein. Except as expressly indicated in writing, Vishay products are not designed for use in medical, life-saving, or life-sustaining applications or for any other application in which the failure of the Vishay product could result in personal injury or death. Customers using or selling Vishay products not expressly indicated for use in such applications do so at their own risk. Please contact authorized Vishay personnel to obtain written terms and conditions regarding products designed for such applications. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document or by any conduct of Vishay. Product names and markings noted herein may be trademarks of their respective owners. 207 VISHAY INTERTECHNOLOGY, INC. ALL RIGHTS RESERVED Revision: 08-Feb-7 Document Number: 9000