PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 10-A, 4.5-V to 14-V INPUT, NON-ISOLATED POWER MODULE FOR 3-GHz DSP SYSTEMS FEATURES • • • • • • • • Up to 10-A Output Current 4.5-V to 14-V Input Voltage Wide-Output Voltage Adjust (0.69 V to 2.0 V) ±1.5% Total Output Voltage Variation Efficiencies up to 92% Output Overcurrent Protection (Nonlatching, Auto-Reset) Operating Temperature: –40°C to 85°C Safety Agency Approvals: – UL/IEC/CSA-C22.2 60950-1 Prebias Startup On/Off Inhibit Differential Output Voltage Remote Sense Adjustable Undervoltage Lockout Auto-Track™ Sequencing SmartSync Technology • • • TurboTrans™ Technology Designed to meet Ultra-Fast Transient Requirements for 3-GHz DSP Systems 15 mV Output Voltage Deviation (CO = 3000 µF, ∆I = 5 A) APPLICATIONS • Wireless Infrastructure Base Stations DESCRIPTION The PTH08T240F is a high-performance 10-A rated, non-isolated power module designed to meet ultra-fast transient requirements for 3-GHz DSP systems. This module represent the 2nd generation of the popular PTH series power modules which include a reduced footprint and additional features. Operating from an input voltage range of 4.5 V to 14 V, the PTH08T240F requires a single resistor to set the output voltage to any value over the range, 0.69 V to 2.0 V. The output voltage range makes the PTH08T240F particularly suitable for the 3-GHz DSP's core voltage requirements between 0.9 V and 1.1 V. Additionally, the wide input voltage range increases design flexibility by supporting operation with 5-V, 8-V, or 12-V intermediate bus architectures. The module incorporates a comprehensive list of features. Output over-current and over-temperature shutdown protects against most load faults. A differential remote sense ensures tight load regulation. An adjustable under-voltage lockout allows the turn-on voltage threshold to be customized. Auto-Track™sequencing is a popular feature that greatly simplifies the simultaneous power-up and power-down of multiple modules in a power system. The PTH08T240F includes new patent pending technologies, TurboTrans™ and SmartSync. The TurboTrans feature optimizes the transient response of the regulator while simultaneously reducing the quantity of external output capacitors required to meet a target voltage deviation specification. TurboTrans allows PTH08T240F to meet the tight transient voltage tolerances required by 3-GHz DSPs with minimal output capacitance. SmartSync allows for switching frequency synchronization of multiple modules, thus simplifying EMI noise suppression tasks and reducing input capacitor RMS current requirements. The module uses double-sided surface mount construction to provide a low profile and compact footprint. Package options include both through-hole and surface mount configurations that are lead (Pb) - free and RoHS compatible. Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Auto-Track, TMS320 are trademarks of Texas Instruments. PRODUCT PREVIEW information concerns products in the formative or design phase of development. Characteristic data and other specifications are design goals. Texas Instruments reserves the right to change or discontinue these products without notice. Copyright © 2006, Texas Instruments Incorporated PRODUCT PREVIEW • • • • • • PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. SmartSync Track TurboTranst 10 VI Track 2 1 9 TT +Sense SYNC VI VO PTH08T240F Inhibit 11 3 PRODUCT PREVIEW CI 330 µF (Required) CI2 22 µF (Optional) VO −Sense GND + RUVLO 1% 0.05 W (Optional) 5 +Sense 7 INH/UVLO GND 6 RTT 1% 0.05 W (Optional) 4 VOAdj 8 RSET [A] 1% 0.05 W (Required) + L O A D CO 1000 µF (Required) GND −Sense GND UDG−06005 A. 2 RSET required to set the output voltage to a value higher than 0.69 V. See Electrical Characteristics table. Submit Documentation Feedback PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 ORDERING INFORMATION For the most current package and ordering information, see the Package Option Addendum at the end of this datasheet, or see the TI website at www.ti.com. DATASHEET TABLE OF CONTENTS PAGE NUMBER 3 ELECTRICAL CHARACTERISTICS TABLE 4 TERMINAL FUNCTIONS 6 TYPICAL CHARACTERISTICS (VI = 12V) 7 TYPICAL CHARACTERISTICS (VI = 5V) 8 ADJUSTING THE OUTPUT VOLTAGE 9 INPUT & OUTPUT CAPACITOR RECOMMENDATIONS 11 TURBOTRANS™ INFORMATION 15 UNDERVOLTAGE LOCKOUT (UVLO) 20 SOFT-START POWER-UP 21 OUTPUT INHIBIT 22 OVER-CURRENT PROTECTION 23 OVER-TEMPERATURE PROTECTION 23 REMOTE SENSE 23 SYCHRONIZATION (SMARTSYNC) 24 AUTO-TRACK SEQUENCING 25 PREBIAS START-UP 28 TAPE & REEL AND TRAY DRAWINGS 30 PRODUCT PREVIEW DATASHEET SECTION ENVIRONMENTAL AND ABSOLUTE MAXIMUM RATINGS ENVIRONMENTAL AND ABSOLUTE MAXIMUM RATINGS (Voltages are with respect to GND) UNIT VTrack Track pin voltage TA Operating temperature range Over VI range Twave Wave soldering temperature Treflow Solder reflow temperature Tstg Storage temperature –0.3 to VI + 0.3 Surface temperature of module body or pins for 5 seconds maximum. suffix AH suffix AD 260 Surface temperature of module body or pins suffix AS 235 (1) suffix AZ 260 (1) Per Mil-STD-883D, Method 2002.3 1 msec, 1/2 sine, mounted Mechanical vibration Mil-STD-883D, Method 2007.2 20-2000 Hz Weight (1) (2) 235 °C –40 to 125 (2) Mechanical shock Flammability V –40 to 85 suffix AH & AD 500 suffix AS & AZ 250 G 15 5 grams Meets UL94V-O During reflow of surface mount package version do not elevate peak temperature of the module, pins or internal components above the stated maximum. The shipping tray or tape and reel cannot be used to bake parts at temperatures higher than 65°C. Submit Documentation Feedback 3 PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 ELECTRICAL CHARACTERISTICS PTH08T240F TA = 25°C, VI = 5 V, VO = 1.0 V, CI = 330 µF, CO = 1000 µF, and IO = IO max (unless otherwise stated) PARAMETER TEST CONDITIONS PTH08T240F MIN IO Output current VI Input voltage range VOADJ Output voltage adjust range Over VO range 25°C, natural convection Over IO range η 10 A 0.69 ≤ VO≤ 1.2 4.5 11 × VO (1) V 1.2 < VO≤ 2.0 4.5 14 Over IO range 0.69 ±0.3 %Vo ±3 mV Load regulation Over IO range ±2 Total output variation Includes set-point, line, load, –40°C ≤ TA ≤ 85°C IO = 10 A 90% RSET = 7.09 kΩ, VO = 1.5 V 88% RSET = 12.1 kΩ, VO = 1.2 V 87% PRODUCT PREVIEW 20-MHz bandwidth Overcurrent threshold Reset, followed by auto-recovery Transient response 2.5 A/µs load step 50 to 100% IOmax VO = 2.5 V w/ TurboTrans CO = tbd µF, Type C, RTT = tbd Ω Track input current (pin 10) Pin to GND dVtrack/dt Track slew rate capability CO ≤ CO (max) UVLOADJ VI increasing, RUVLO = OPEN Adjustable Under-voltage lockout VI decreasing, RUVLO = OPEN (pin 11) Hysteresis, RUVLO≤ 52.3 kΩ (3) A tbd µs VO over/undershoot tbd mV Recovery time tbd µs tbd mV VO over/undershoot 1 4.3 4.0 Inhibit (pin 11) to GND, Track (pin 10) open fs Switching frequency Over VI and IO ranges, SmartSync (pin 1) to GND fSYNC Synchronization (SYNC) frequency VSYNCH SYNC High-Level Input Voltage VSYNCL SYNC Low-Level Input Voltage tSYNC SYNC Minimum Pulse Width CI External input capacitance (6) 4 4.45 4.2 V Open (5) -0.2 Input low current (IIL), Pin 11 to GND Input standby current µA V/ms 0.5 Input low voltage (VIL) Iin (5) mVPP Recovery time Input high voltage (VIH) (4) %Vo 20 –130 (4) IIL Inhibit control (pin 11) (2) 85% 10 w/o TurboTrans CO = 1000 µF, Type C mV ±1.5 RSET = 4.78 kΩ, VO = 1.8 V VO Ripple (peak-to-peak) ∆VtrTT (3) V %Vo Over VI range ∆Vtr (2) (2) –40°C < TA < 85°C ttr (1) ±1 Line regulaltion RSET = 20.8 kΩ, VO = 1.0 V ttrTT 2.0 ±0.5 Temperature variation Efficiency ILIM UNIT MAX 0 Set-point voltage tolerance VO TYP 260 0.8 -235 µA 5 mA 300 340 kHz 240 400 kHz 2 5.5 V 0.8 200 Nonceramic Ceramic V 330 V nSec (6) 22 (6) µF The maximum input voltage is duty cycle limited to (VO× 11) or 14 volts, whichever is less. The maximum allowable input voltage is a function of switching frequency, and may increase or decrease when the SmartSync feature is utilized. Please review the SmartSync section of the Application Information for further guidance. The set-point voltage tolerance is affected by the tolerance and stability of RSET. The stated limit is unconditionally met if RSET has a tolerance of 1% with 100 ppm/°C or better temperature stability. For output voltages less than 1.7 V, the ripple may increase (up to 2×) when operating at input voltages greater than (VO× 11). See the SmartSync section of the Application Information for input voltage and frequency limitations. A low-leakage (<100 nA), open-drain device, such as MOSFET or voltage supervisor IC, is recommended to control pin 10. The open-circuit voltage is less than 8 Vdc. This control pin has an internal pull-up. Do not place an external pull-up on this pin. If it is left open-circuit, the module operates when input power is applied. A small, low-leakage (<100 nA) MOSFET is recommended for control. For additional information, see the related application information section. A 330 µF electrolytic input capacitor is required for proper operation. The electrolytic capacitor must be rated for a minimum of 500 mA rms of ripple current. Submit Documentation Feedback PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 ELECTRICAL CHARACTERISTICS (continued) PTH08T240F TA = 25°C, VI = 5 V, VO = 1.0 V, CI = 330 µF, CO = 1000 µF, and IO = IO max (unless otherwise stated) PARAMETER TEST CONDITIONS PTH08T240F MIN w/o TurboTrans CO Capacitance Value Nonceramic w/ TurboTrans Capacitance Value Capacitance × ESR product (CO× ESR) MTBF (8) (9) UNIT MAX 5000 (8) 500 7 mΩ see table µF (7) (9) 1000 6.1 µF 10000 (9) µF×mΩ 106 Hr 1000 µF of external output capacitance is required for basic operation. The minimum output capacitance requirement increases when TurboTrans™ (TT) technology is utilized. See related Application Information for more guidance. This is the calculated maximum disregarding TurboTrans™ technology. When the TurboTrans™ feature is utilized, the minimum output capacitance must be increased. When using TurboTrans™ technology, a minimum value of output capacitance is required for proper operation. Additionally, low ESR capacitors are required for proper operation. See the application notes for further guidance. PRODUCT PREVIEW (7) Reliability Per Telcordia SR-332, 50% stress, TA = 40°C, ground benign (7) Ceramic Equivalent series resistance (non-ceramic) External output capacitance 1000 TYP Submit Documentation Feedback 5 PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 TERMINAL FUNCTIONS TERMINAL NAME NO. DESCRIPTION VI 2 The positive input voltage power node to the module, which is referenced to common GND. VO 5 The regulated positive power output with respect to GND. GND Inhibit (1) and UVLO Vo Adjust 3, 4 11 This is the common ground connection for the VI and VO power connections. It is also the 0 Vdc reference for the control inputs. The Inhibit pin is an open-collector/drain, negative logic input that is referenced to GND. Applying a low level ground signal to this input disables the module’s output and turns off the output voltage. When the Inhibit control is active, the input current drawn by the regulator is significantly reduced. If the Inhibit pin is left open-circuit, the module produces an output whenever a valid input source is applied. This pin is also used for input undervoltage lockout (UVLO) programming. Connecting a resistor from this pin to GND (pin 3) allows the ON threshold of the UVLO to be adjusted higher than the default value. For more information, see the Application Information section. 8 A 0.05 W 1% resistor must be directly connected between this pin and pin 7 (–Sense) to set the output voltage to a value higher than 0.69 V. The temperature stability of the resistor should be 100 ppm/°C (or better). The setpoint range for the output voltage is from 0.69 V to 2.0 V. If left open circuit, the output voltage will default to its lowest value. For further information, on output voltage adjustment see the related application note. The specification table gives the preferred resistor values for a number of standard output voltages. PRODUCT PREVIEW + Sense 6 The sense input allows the regulation circuit to compensate for voltage drop between the module and the load. For optimal voltage accuracy, +Sense must be connected to VO, very close to the load. – Sense 7 The sense input allows the regulation circuit to compensate for voltage drop between the module and the load. For optimal voltage accuracy –Sense must be connected to GND (pin 4) very close to the module (within 10 cm). 10 This is an analog control input that enables the output voltage to follow an external voltage. This pin becomes active typically 20 ms after the input voltage has been applied, and allows direct control of the output voltage from 0 V up to the nominal set-point voltage. Within this range the module's output voltage follows the voltage at the Track pin on a volt-for-volt basis. When the control voltage is raised above this range, the module regulates at its set-point voltage. The feature allows the output voltage to rise simultaneously with other modules powered from the same input bus. If unused, this input should be connected to VI. Track NOTE: Due to the undervoltage lockout feature, the output of the module cannot follow its own input voltage during power up. For more information, see the related application note. TurboTrans™ SmartSync (1) 9 This input pin adjusts the transient response of the regulator. To activate the TurboTrans™ feature, a 1%, 50 mW resistor must be connected between this pin and pin 6 (+Sense) very close to the module. For a given value of output capacitance, a reduction in peak output voltage deviation is achieved by utililizing this feature. If unused, this pin must be left open-circuit. The resistance requirement can be selected from the TurboTrans™ resistor table in the Application Information section. External capacitance must never be connected to this pin unless the TurboTrans resistor value is a short, 0Ω. 1 This input pin sychronizes the switching frequency of the module to an external clock frequency. The SmartSync feature can be used to sychronize the switching fequency of multiple PTH08T240F modules, aiding EMI noise suppression efforts. If unused, this pin should be connected to GND (pin 3). For more information, please review the Application Information section. Denotes negative logic: Open = Normal operation, Ground = Function active 11 1 10 2 9 8 7 PTH08T240F (Top View) 3 6 4 6 5 Submit Documentation Feedback PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 TYPICAL CHARACTERISTICS (1) (2) CHARACTERISTIC DATA (VI = 12 V) EFFICIENCY vs LOAD CURRENT OUTPUT RIPPLE vs LOAD CURRENT 16 4.0 VI = 12 V VO = 1.8 V VI = 12 V 90 VI = 12 V 80 3.5 PD − Power Dissipation − W VO − Output Voltage Ripple − mVPP 14 12 70 3.0 10 VO = 1.2 V 60 50 40 VO (V) 1.8 1.2 30 2 4 6 8 2.5 8 6 1.5 4 VO = 1.2 V 1.0 VO (V) VO = 1.2 V VO (V) 1.8 1.2 0.5 0 10 VO = 1.8 V 2.0 2 20 0 VO = 1.8 V 0 0 IO − Output Current − A 1.8 1.2 2 4 6 8 IO − Output Current − A Figure 1. 10 Figure 2. 0 2 4 6 IO − Output Current − A 8 10 PRODUCT PREVIEW 100 η − Efficiency − % POWER DISSIPATION vs LOAD CURRENT Figure 3. SAFE OPERATING AREA TA − Ambient Temperature − °C 90 Natural Convection 80 70 60 50 40 30 VI = 12 V VO = 1.2 V 20 0 2 4 6 8 10 IO − Output Current − A Figure 4. (1) (2) The electrical characteristic data has been developed from actual products tested at 25°C. This data is considered typical for the converter. Applies to Figure 1, Figure 2, and Figure 3. The temperature derating curves represent the conditions at which internal components are at or below the manufacturer's maximum operating temperatures. Derating limits apply to modules soldered directly to a 100 mm x 100 mm double-sided PCB with 2 oz. copper. For surface mount packages (AS and AZ suffix), multiple vias must be utilized. Please refer to the mechanical specification for more information. Applies to Figure 4. Submit Documentation Feedback 7 PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 TYPICAL CHARACTERISTICS (1) (2) CHARACTERISTIC DATA (VI = 5 V) EFFICIENCY vs LOAD CURRENT OUTPUT RIPPLE vs LOAD CURRENT 2.5 10 VO = 1.8 V VO − Output Voltage Ripple − mVPP 90 80 VO = 0.7 V 70 VO = 0.9 V VO = 1.2 V 60 50 VO (V) 0.7 0.9 1.2 1.8 40 VI = 5 V VI = 5 V VI = 5 V VO = 1.8 V 2.0 8 VO = 1.2 V 6 0 2 PRODUCT PREVIEW 4 6 IO − Output Current − A 8 4 VO = 1.8 V 1.0 VO = 0.7 V VO (V) 0.7 0.9 1.2 1.8 2 VO = 0.7 V 0.5 VO = 0.9 V 0 0 10 VO = 1.2 V 1.5 VO = 0.9 V 0 30 VO (V) 0.7 0.9 1.8 1.2 PD − Power Dissipation − W 100 η − Efficiency − % POWER DISSIPATION vs LOAD CURRENT 2 4 6 IO − Output Current − A Figure 5. 8 10 Figure 6. 0 2 4 6 IO − Output Current − A 8 10 Figure 7. SAFE OPERATING AREA TA − Ambient Temperature − °C 90 80 Natural Convection 70 60 50 40 30 VI = 5 V All VO 20 0 2 4 6 8 10 IO − Output Current − A Figure 8. (1) (2) 8 The electrical characteristic data has been developed from actual products tested at 25°C. This data is considered typical for the converter. Applies to Figure 5, Figure 6, and Figure 7. The temperature derating curves represent the conditions at which internal components are at or below the manufacturer's maximum operating temperatures. Derating limits apply to modules soldered directly to a 100 mm x 100 mm double-sided PCB with 2 oz. copper. For surface mount packages (AS and AZ suffix), multiple vias must be utilized. Please refer to the mechanical specification for more information. Applies to Figure 8. Submit Documentation Feedback PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 APPLICATION INFORMATION ADJUSTING THE OUTPUT VOLTAGE The Vo Adjust control (pin 8) sets the output voltage of the PTH08T240F. The adjustment range is 0.69 V to 2.0 V. The adjustment method requires the addition of a single external resistor, RSET, that must be connected directly between the VO Adjust and – Sense pins. Table 1 gives the standard value of the external resistor for a number of standard voltages, along with the actual output voltage that this resistance value provides. For other output voltages, the value of the required resistor can either be calculated using the following formula, or simply selected from the range of values given in Table 2. Figure 9 shows the placement of the required resistor. RSET = 10 kW x 0.69 - 1.43 kW VO - 0.69 (1) RSET (Standard Value) (kΩ) VO (Actual) (V) 1.8 4.75 1.807 1.5 6.98 1.510 12.1 1.200 20.5 1.004 681 0.700 1.2 1 (1) 0.7 (1) (1) (1) PRODUCT PREVIEW Table 1. Standard Values of RSET for Standard Output Voltages VO (Standard) (V) The maximum input voltage is (VO× 11) or 14 V, whichever is less. The maximum allowable input voltage is a function of switching frequency and may increase or decrease when the Smart Sync feature is utilized. Please review the Smart Sync application section for further guidance. 6 +Sense +Sense PTH08T240F VO VO 5 7 −Sense GND GND VoAdj 3 8 + 4 CO RSET 1% 0.05 W −Sense GND UDG−06077 (1) RSET: Use a 0.05 W resistor with a tolerance of 1% and temperature stability of 100 ppm/°C (or better). Connect the resistor directly between pins 8 and 7, as close to the regulator as possible, using dedicated PCB traces. (2) Never connect capacitors from VO Adjust to either + Sense, GND, or VO. Any capacitance added to the VO Adjust pin affects the stability of the regulator. Figure 9. VO Adjust Resistor Placement Submit Documentation Feedback 9 PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 Table 2. Output Voltage Set-Point Resistor Values (Standard Values) VO Required (V) PRODUCT PREVIEW (1) 10 RSET (kΩ) 0.70 (1) 0.75 (1) 113 0.80 (1) 61.9 0.85 (1) 41.2 0.90 (1) 31.6 0.95 (1) 24.9 1.00 (1) 20.5 1.05 (1) 17.8 1.10 (1) 15.4 1.15 (1) 13.3 1.20 (1) 12.1 1.25 (1) 10.7 1.30 9.88 1.35 9.09 1.40 8.25 1.45 7.68 1.50 6.98 1.55 6.49 1.60 6.04 1.65 5.76 1.70 5.36 1.75 5.11 1.80 4.75 1.85 4.53 1.90 4.22 1.95 4.02 2.00 3.83 681 The maximum input voltage is (VO× 11) or 14 V, whichever is less. The maximum allowable input voltage is a function of switching frequency and may increase or decrease when the Smart Sync feature is utilized. Please review the Smart Sync application section for further guidance. Submit Documentation Feedback PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 TurboTrans™ Technology TurboTrans technology is a feature introduced in the T2 generation of the PTH/PTV family of power modules. TurboTrans optimizes the transient response of the regulator with added external capacitance using a single external resistor. Benefits of this technology include reduced output capacitance, minimized output voltage deviation following a load transient, and enhanced stability when using ultra-low ESR output capacitors. The amount of output capacitance required to meet a target output voltage deviation will be reduced with TurboTrans activated. Likewise, for a given amount of output capacitance, with TurboTrans engaged, the amplitude of the voltage deviation following a load transient will be reduced. Applications requiring tight transient voltage tolerances and minimized capacitor footprint area will benefit greatly from this technology. TurboTrans™ Selection Figure 10 shows the amount of output capacitance required to meet a desired transient voltage deviation with and without TurboTrans for Type C (e.g. OS-CON) capacitors; Type B (e.g. polymer-tantalum) capacitor charts will be added. To calculate the proper value of RTT, first determine your required transient voltage deviation limits and magnitude of your transient load step. Next, determine what type of output capacitors will be used. (If more than one type of output capacitor is used, select the capacitor type that makes up the majority of your total output capacitance.) Knowing this information, use the chart (Figure 10; for Type C capacitors) that corresponds to the capacitor type selected. To use the chart, begin by dividing the maximum voltage deviation limit (in mV) by the magnitude of your load step (in Amps). This gives a mV/A value. Find this value on the Y-axis of the appropriate chart. Read across the graph to the 'With TurboTrans' plot. From this point, read down to the X-axis which lists the minimum required capacitance, CO, to meet that transient voltage deviation. The required RTT resistor value can then be calculated using the equation or selected from the TurboTrans table. The TurboTrans tables include both the required output capacitance and the corresponding RTT values to meet several values of transient voltage deviation for 25% (2.5 A), 50% (5 A), and 75% (7.5 A) output load steps. The chart can also be used to determine the achievable transient voltage deviation for a given amount of output capacitance. By selecting the amount of output capacitance along the X-axis, reading up to the desired 'With TurboTrans'' curve, and then over to the Y-axis, gives the transient voltage deviation limit for that value of output capacitance. The required RTT resistor value can be calculated using the equation or selected from the TurboTrans table. As an example, let's look at a 5-V application requiring a 15 mV deviation during an 5 A, 50% load transient. A majority of 680 µF, 10 mΩ ouput capacitors will be used. Use the 5-V, Type C capacitor chart, Figure 10. Dividing 15 mV by 5 A gives 3 mV/A transient voltage deviation per amp of transient load step. Select 3 mV/A on the Y-axis and read across to the 'With TurboTrans'' plot. Following this point down to the X-axis gives a minimum required output capacitance of approximately 3000 µF. The required RTT resistor value for 3000 µF can then be calculated or selected from Table 3. The required RTT resistor is approximately 13.0 kΩ. Submit Documentation Feedback 11 PRODUCT PREVIEW Utilizing TurboTrans requires connecting a resistor, RTT, between the +Sense pin (pin 6) and the TurboTrans pin (pin 9). The value of the resistor directly corresponds to the amount of output capacitance required. All T2 products require a minimum value of output capacitance whether or not TurboTrans is utilized. For the PTH08T240F, the minimum required capacitance is 1000 µF. When using TurboTrans, capacitors with a capacitance × ESR product below 10,000 µF×mΩ are required. (Multiply the capacitance (in µF) by the ESR (in mΩ) to determine the capacitance × ESR product.) See the Capacitor Selection section of the datasheet for a variety of capacitors that meet this criteria. PTH08T240F www.ti.com SLTS277 – DECEMBER 2006 PTH08T240F Type C Capacitors 5-V Input 10 9 8 7 Without TurboTrans 6 Transient −mV/A 5 4 3 2 With TurboTrans 7000 8000 9000 10000 6000 5000 4000 3000 2000 1000 PRODUCT PREVIEW 1 C − Capacitance − µF Figure 10. Capacitor Type C, 5000 < C(µF)×ESR(mΩ) ≤ 10,000 (e.g. OS-CON) Table 3. Type C TurboTrans CO Values and Required RTT Selection Table Transient Voltage Deviation (mV) 5-V Input 25% load step (2.5 A) 50% load step (5 A) 75% load step (7.5 A) CO Minimum Required Output Capacitance (µF) RTT Required TurboTrans Resistor (kΩ) 23 45 68 1000 open 20 40 60 1150 274 18 35 53 1300 133 15 30 45 1500 76.8 13 25 38 1810 44.2 10 20 30 2300 24.9 8 15 23 3050 12.7 5 10 15 4620 3.74 RTT Resistor Selection The TurboTrans resistor value, RTT can be determined from the TurboTrans programming, see Equation 2 . 40 R TT + ƪǒǒǒ5 ƪ1 * ǒC Oń6300Ǔƫ Ǔ ƫ C OǓ ) 1300Ǔń6300 * 1 (kW) (2) Where CO is the total output capacitance in µF. CO values greater than or equal to 6300 µF require RTT to be a short, 0Ω. (RTT results in a negative value when CO > 6300 µF). 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