PT7742—3.3V 20 Amp “Current Booster” for PT7708 Integrated Switching Regulator SLTS085 (Revised 6/30/2000) Description The PT7742 is a 20 Amp “Current Booster” for the PT7708 housed in the same 27-pin SIP package. Multiple PT7742 boosters will operate in parallel with one PT7708 product, boosting output current in increments of 20A. Combinations of a PT7708 regulator and PT7742 current boosters can supply power for virtually any multiple mega-processor application. A PT7742 current booster adds a parallel output stage that is driven directly by the regulator. This allows the system to run in perfect synchronization to provide a low noise solution. The PT7742 only operates in combination with a PT7708 series regulator, and is not a stand-alone product. Please refer to the PT7708 data sheet for the performance specifications. The booster uses the same 27-pin case and has the same package options as its companion regulator. Pin-Out Information Ordering Information PT7742❏ Pin Function Features • • • • 20A Current Boost Tracks Vo of a PT7708 High Efficiency Input Voltage Range: 3.1V to 3.6V • Synchronized with PT7708 • 27-pin SIP Package • Connect up to 2 in Parallel for 60 Amps Pin Function 1 Do not connect 14 GND 2 Do not connect 15 GND 3 Do not connect 16 GND 4 Do not connect 17 GND 5 Do not connect 18 GND 6 Do not connect 19 GND 7 Vin 20 Vout 8 Vin 21 Vout (For dimensions and PC Board layout, see Package Styles 800 and 810.) PT Series Suffix (PT1234X) Case/Pin Configuration Vertical Through-Hole Horizontal Through-Hole 9 Vin 22 Vout 10 Vin 23 Vout 11 Vin 24 Vout 12 Do not connect 25 Vout 13 GND 26 Do not connect 27 Master Sync In Horizontal Surface Mount N A C Standard Application PROGRAMMING PINS VID0 VID1 VID2 VID3 REMOTE SENSE (+) 4 3 2 1 26 SNS(+) VID3 - VID0 V IN L1 7-11 PT7708 Vin 1 H + STBY Synch Out 5 27 C IN GND 13-19 Vo V OUT 20-25 SNS(-) + 12 LOAD C OUT GND GND STBY* REMOTE SENSE ( ) 27 Synch In L1 7-11 1 H + C IN Vin PT7742 Vo 20-25 GND 13-19 + C OUT External Capacitors: The PT7742 requires a minimum ouput capacitance of 330µF for proper operation. The PT7742 also requires an input capacitance of 1500µF, which must be rated for a minimum of 1.4Arms of ripple current. For transient or dynamic load applications additional capacitance may be required. For more information refer to the application note regarding capacitor selection for this product. Input Filter: An input filter inductor is optional for most applications. The inductor must be sized to handle 20ADC with a typical value of 1µH. For technical support and more information, see inside back cover or visit www.ti.com/powertrends Application Notes PT7708/PT7709, PT7742/PT7743 Capacitor Recommendations for the PT7708/09 Regulators and PT7742/43 Current Boosters Input Capacitors The recommended input capacitance is determined by 1.4 ampere minimum ripple current rating and 1500µF minimum capacitance. Capacitors listed below must be rated for a minimum of 2x the input voltage with +5V operation. Ripple current and ≤100mΩ Equivalent Series Resistance (ESR) values are the major considerations along with temperature when selecting the proper capacitor. Output Capacitors The minimum required output capacitance is 330µF with a maximum ESR less than or equal to 100mΩ. Failure to observe this requirement may lead to regulator instability or oscillation. Electrolytic capacitors have poor ripple performance at frequencies greater than 400kHz, but excellent low frequency transient response. Above the ripple frequency ceramic decoupling capacitors are necessary to improve the transient response and reduce any microprocessor high frequency noise components apparent during higher current excursions. Preferred low ESR type capacitor part numbers are identified in the Table 1 below. Tantalum Characteristics Tantalum capacitors with a minimum 10V rating are recommended on the output bus, but only the AVX TPS Series, Sprague 594/595 Series, or Kemet T495/T510 Series. The AVX TPS Series, Sprague Series or Kemet Series capacitors are specified over other types due to their higher surge current, excellent power dissipation and ripple current ratings. As an example, the TAJ Series by AVX is not recommended. This series exhibits considerably higher ESR, reduced power dissipation and lower ripple current capability. The TAJ Series is a less reliable compared to the TPS series when determining power dissipation capability. Capacitor Table Table 1 identifies the characteristics of capacitors from a number of vendors with acceptable ESR and ripple current (rms) ratings. The suggested minimum quantities per regulator for both the input and output buses are identified. This is not an extensive capacitor list. The table below is a selection guide for input and output capacitors. Other capacitor vendors are available with comparable RMS ripple current rating and ESR (Equivalent Series Resistance at 100kHz). These critical parameters are necessary to insure both optimum regulator performance and long capacitor life. Table 1 Capacitors Characteristic Data Capac i t or Ve n d o r / Ser i es Capac i t or Char ac t e r i s t i c s Qu a n t i t y Working Voltage Value(µF) ( ESR) Equi v al e nt Se r i e s Re s i s t anc e 1 0 5 ° C Ma x i m u m Ri ppl e C u r r e n t ( I r ms ) Phy s i c al S i z e ( mm) I nput Bu s Ou t p u t Bu s Panasonic FC Surface Mtg FA 16V 35V 2200 330 0.038Ω 0.065Ω 2000mA 1205mA 18x16.5 12.5x16.5 1 1 1 EEVFC1C222N EEVFC1V331LQ 10V 16V 680 1800 0.090Ω 0.032Ω 755mA 2000mA 10x12.5 18x15 1 1 1 EEUFA1A681 EEUFA1C182A United Chemi -Con LFVSeries 25V 16V 16V 330 2200 470 0.084Ω 0.038Ω 0.084Ω/2=042Ω 825mA 1630mA 825mA x2 10x16 16x20 10x16 1 1 1 1 LXV25VB331M10X16LL LXV16VB222M16X20LL LXV16VB471M10X16LL Nichicon PL Series PM Series 10V 10V 25V 680 1800 330 0.090Ω 0.044Ω 0.095Ω 770mA 1420mA 750mA 10x15 16x15 10x15 1 1 1 1 UPL1A681MHH6 UPL1A182MHH6 UPL1E331MPH6 Oscon SS SV 10V 10V 330 330 0.025W/4=0.006Ω 0.020/4=0.005Ω >9800mA >9800mA 10x10.5 10.3x12.6 4 4 N/R (Note) AVX Tanatalum TPS- Series 10V 10V 330 330 0.100/5=20Ω 0.060Ω 3500mA 1826mA 7.3Lx 4.3Wx 4.1H 5 5 1 1 TPSV337M010R0100 TPSV337M010R0060 Sprague Tantalum 595D/594D 10V 330 0.045W/4=0.011Ω >4500mA 5 1 10V 680 0.090Ω >1660mA 7.3L x 5.7W x 4.0H 2 1 594D337X0010R2T Surface Mount 595D687X0010R2T Kemet Tantalum T510/T495 Series 10V 330 0.035Ω 2000mA 10V 220 0.070Ω/2=0.035Ω >2000mA Sanyo Poscap TPB 10V 220 0.040Ω 3000mA 4.3Wx7.3L x4.0H 7.2L x 4.3W x 3.1H Note: (N/R) is not recommended for this application, due to extremely low Equivalent Series Resistance (ESR) For technical support and more information, see inside back cover or visit www.ti.com/powertrends Vendor Number 10SS330M 10SV330M(Sufvace Mtg 5 1 510X337M010AS 6 2 T495X227M010AS Surface Mount 6 2 10TPB220M Surface Mount I MPORTANT NOTI CE Te xas Instrume nts and its subsidiarie s (TI) re se rve the right to make change s to the ir products or to discontinue any product or se rvice without notice , and advise custome rs to obtain the late st ve rsion of re le vant information to ve rify, be fore placing orde rs, that information be ing re lie d on is curre nt and comple te . 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