ATH26K12-9S

ATH26K12 Series - 12-V Input 26-A, 12-V Input Non-Isolated Wide-Output Adjust Power Module REVISION 00 (30APR2004) Features NOMINAL SIZE = 1.37 in x 1.12 in (34,8 mm x 28,5 mm) • Up to 26 A Output Current • 12-V Input Voltage • Wide-Output Voltage Adjust (1.2 V to 5.5 V) • Efficiencies up to 94 % • 235 W/in³ Power Density • On/Off Inhibit • Output Voltage Sense • Pre-Bias Startup • Margin Up/Down Controls • Dual-Phase Topology • Auto-Track™ Sequencing • Under-Voltage Lockout • Output Over-Current Protection (Non-Latching, Auto-Reset) • Over-Temperature Protection • Operating T emp: –40 to +85 °C • Safety Agency Approvals: UL 1950, CSA 22.2 950, EN60950 VDE (Pending) • Point-of-Load Alliance (POLA) Compatible Description The ATH26K12 is a series of highcurrent non-isolated power module. This product is characterized by high efficiencies, and up to 26 A of output current, while occupying a mere 1.64 in² of PCB area. In terms of cost, size, and performance, the series provides OEM’s with a flexible module that meets the requirements of the most complex and demanding mixed-signal applications. These include the most densly populated, multi-processor systems that incorporate high-speed DSP’s, microprocessors, and ASICs. The series uses double-sided surface mount construction and provides highperformance step-down power conversion from a 12-V input bus voltage. The out- put voltage of the ATH26K12 can be set to any value over the range, 1.2 V to 5.5 V, using a single resistor. This series includes Auto-Track™. Auto-Track simplifies power-up and power-down supply voltage sequencing in a system by enabling modules to track each other, or any other external voltage. Each model also includes an on/off inhibit, output voltage adjust (trim), and margin up/down controls. An output voltage sense ensures tight load regulation, and an output over-current and thermal shutdown feature provide for protection against external load faults. Package options inlude both throughhole and surface mount connfigurations. Pin Configuration Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 Function GND Vin GND Inhibit * Vo Adjust Vo Sense GND Vout Vout GND Track Margin Down * Margin Up * * Denotes negative logic: Open = Normal operation Ground = Function active Standard Application Track Margin Down Margin Up 13 1 12 11 10 ack™ uto-Tr cing A en Sequ Rset = Required to set the output voltage to a value higher than 1.2 V. (See spec. table for values) Cin = Required electrolytic 560 µF Cout = Optional 330 µF electrolytic VIN 2 ATH26K12-9S (Top View) PTH12030W 9 8 7 VOUT 3 4 5 6 Inhibit Vo Sense CIN 560 µF (Required) RSET 1 %, 0.1 W (Required) COUT 330 µF (Optional) L O A D GND GND North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662 ATH26K12 Series —12-V Input 26-A, 12-V Input Non-Isolated Wide-Output Adjust Power Module REVISION 00 (30APRIL2004) Ordering Information Input Voltage 10.8V to 13.2V Options: “-J” “-SJ” - Output Voltage 1.2V1 to 5.5V Output Current 26A Model Number ATH26K12-9(S)(J) Through-hole Termination, Tray Packaging SMT Termination, Tray Packaging Notes: 1 Preset output voltage is 1.2V; externally adjustable to 5.5V through the Vo,Adjust pin Pin Descriptions Vin: The positive input voltage power node to the module, which is referenced to common GND. Vout: The regulated positive power output with respect to the GND node. GND: This is the common ground connection for the Vin and Vout power connections. It is also the 0 VDC reference for the control inputs. Inhibit: The Inhibit pin is an open-collector/drain negative logic input that is referenced to GND. Applying a lowlevel ground signal to this input disables the module’s o utput and turns o ff the o utput vo ltage. When the Inhibit control is active, the input current drawn by the regulator is significantly reduced. If the I nhibit p in is left open-circuit, the module will produce an output whenever a valid input source is applied. Vo Adjust: A 0.1 W, 1 % tolerance (or better) resistor must be connected directly between this pin and the output ground (pin 10) to set the output voltage to the desired value. The set point range for the output voltage is from 1.2 V to 5.5 V. The resistor required for a given output voltage may be calculated from the following formula. If left open circuit, the module output will default to its lowest output voltage value. For further information on output voltage adjustment consult the related application note. R set Vo Sense: The sense input allows the regulation circuit to compensate for voltage drop between the module and the load. For optimal voltage accuracy Vo Sense should be connected to Vout. It can also be left disconnected. Track: 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 output will follow 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 b e c o nne c ted to V in. Note: Due to the under-voltage lockout feature, the output of the module cannot follow its own input voltage during power up. For more information, consult the related application note. Margin Down: When this input is asserted to GND, the output voltage is decreased by 5% from the nominal. The input requires an open-collector (open-drain) interface. It is not TTL compatible. A lower percent change can be accomodated with a series resistor. For further information, consult the related application note. Margin Up: When this input is asserted to GND, the output voltage is increased by 5%. The input requires an open-collector (open-drain) interface. It is not TTL compatible. The percent change can be reduced with a series resistor. For further information, consult the related application note. 0.8 V = 10 k · Vout – 1.2 V – 1.82 k The specification table gives the preferred resistor values for a number of standard output voltages. North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662 ATH26K12 Series —12-V Input 26-A, 12-V Input Non-Isolated Wide-Output Adjust Power Module REVISION 00 (30APR2004) Environmental & Absolute Maximum Ratings Characteristics Signal Input Voltages Operating T emperature Range Solder Reflow T emperature Storage T emperature Mechanical Shock Mechanical Vibration Weight Flammability — — Ta T reflow Ts (Voltages are with respect to GND) Min –0.3 –0.3 –40 –40 — — — Typ — — — — 500 15 10 Max Vin + 0.3 5 85 235 (i) 125 — — — Units V °C °C °C G’s G’s grams Symbols Conditions Track control (pin 11) Inhibit control (pin 4) Over Vin Range Surface temperature of module body or pins — Per Mil-STD-883D, Method 2002.3 1 msec, ½ Sine, mounted Mil-STD-883D, Method 2007.2 20-2000 Hz Meets UL 94V-O Notes: (i) During reflow of SMD package version do not elevate peak temperature of the module, pins or internal components above the stated maximum. Specifications Characteristics Output Current (Unless otherwise stated, Ta =25 °C, V in =12 V, V out =3.3 V, C in =560 µF, C out =0 µF, and Io =Iomax) Symbols Io V in Conditions 60 °C, 200 LFM airflow 25 °C, natural convection Over Io range –40 °C 3500 mA 4700 mA >1723 mA >1723 mA Physical Size(mm) 10×12.5 12.5×15 10×10.2 12.5×13.5 10×10.5 10×12.5 10×16 10 × 12.5 10×12.2 12.5×15 10×16 16×15 10×10.2 7.3×4.3× − 4.2 7.3L ×5.7W 10×10.5 11×12 7.3L ×5.7W ×4.1H 4.3W ×7.3L ×4.0H 7.2L×6W ×4.1H 16×25 1210 case 3225 mm 1210 case 3225 mm Input Bus 2 1 2 1 2 2 1 2 2 1 1 1 2 N/R [1] N/R [1] 2 [3] 2 N/R [1] N/R [1] Optional Output Bus 1 1 1 1 ≤3 1 1 ≤3 ≤3 1 1 1 Vendor Part Number EEUFC1E331 EEUFC1E561S EEVFK1E471P EEVFK1V681Q 16FX330M LXZ25VB331M10X12LL LXZ16VB681M10X16LL 16PS330MJ12 PXA16VCMJ12 UPM1E561MHH6 UHD1C681MHR UPM1V561MHH6 EEFWA1C331P ≤3 ≤1 [2] EEFSE0J181R (Vo≤5.1V) ≤4 ≤3 ≤3 ≤5 [2] ≤5 [2] 10TPE330M 16SP270M 16SVP330M TPSE477M010R0045 (Vo≤5.1V) TPSE337M010R0045 (Vo≤5.1V) 10 V 10 V 6.3 V 10 V 16 V 16 V 6.3 V 6.3 V 6.3 V 16 V 16 V 6.3 V 6.3 V 16 V 16 V 330 330 470 470 1,000 10 47 100 47 22 10 100 47 22 10 0.040 Ω 0.015 Ω 0.012 Ω 0.100 Ω 0.015 Ω 0.002 Ω 0.002 Ω 0.002 Ω 1800 mA >3800 mA 4200 mA 1440 mA 9740 mA — — N/R [1] N/R [1] N/R [1] N/R [1] 1 1 [4] N/R [1] N/R [1] N/R [1] 1 [4] 1 [4] N/R [1] N/R [1] 1 [4] 1 [4] ≤5 ≤2 ≤2 [2] T520X337M010AS T530X337M010AS T530X477M006AS (Vo≤5.1V) ≤5 [2] 595D477X0010R2T (Vo≤5.1V ≤2 ≤5 ≤5 ≤3 ≤5 ≤5 ≤5 ≤3 ≤5 ≤5 ≤5 94SA108X0016HBP C1210C106M4PAC C1210C476K9PAC GRM32ER60J107M GRM32ER60J476M GRM32ER61C226K GRM32DR61C106K C3225X5R0J107MT C3225X5R0J476MT C3225X5R1C226MT C3225X5R1C106MT TDK, Ceramic X5R (SMD) 0.002 Ω — 1210 case 3225 mm [1] [2] [3] [4] N/R –Not recommended. The voltage rating does not meet the minimum operating limits. The voltage rating of this capacitor only allows it to be used for output voltages that are equal to or less than 5.1 V. Total capacitance of 540 µF is acceptable based on the combined ripple current rating. Small ceramic capacitors may used to complement electrolytic types at the input to further reduce high-frequency ripple current. North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662 Application Notes ATH26K12 Series Adjusting the Output Voltage of the ATH26K12 Wide-Output Adjust Power Module The Vo Adjust control (pin 5) sets the output voltage of the ATH26K12 product. The adjustment range is from 1.2 V to 5.5 V. To adjust the output voltage above 1.2 V a single external resistor, R set, must be connected directly between the Vo Adjust and the GND pins 1. Table 2-1 gives the preferred value for 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 2-2. Figure 2-1 shows the placement of the required resistor. Rset = 10 kΩ · 0.8 V Vout – 1.2 V – 1.82 kΩ Table 2-2; Output Voltage Set-Point Resistor Values Va Req’d 1.200 1.225 1.250 1.275 1.300 1.325 1.350 1.375 1.400 1.425 1.450 1.475 1.50 1.55 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 2.05 2.10 2.15 2.20 2.25 2.30 2.35 2.40 2.45 2.50 2.55 2.60 2.65 2.70 Rset Open 318 κΩ 158 κΩ 105 κΩ 78.2 κΩ 62.2 κΩ 51.5 κΩ 43.9 κΩ 38.2 κΩ 33.7 κΩ 30.2 κΩ 27.3 κΩ 24.8 κΩ 21 κΩ 18.2 κΩ 16 κΩ 14.2 κΩ 12.7 κΩ 11.5 κΩ 10.5 κΩ 9.61 κΩ 8.85 κΩ 8.18 κΩ 7.59 κΩ 7.07 κΩ 6.6 κΩ 6.18 κΩ 5.8 κΩ 5.45 κΩ 5.14 κΩ 4.85 κΩ 4.85 κΩ 4.33 κΩ 4.11 κΩ 3.89 κΩ 3.7 κΩ 3.51 κΩ Va Req’d 2.75 2.80 2.85 2.90 2.95 3.00 3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45 3.50 3.55 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 Rset 3.34 κΩ 3.18 κΩ 3.03 κΩ 2.89 κΩ 2.75 κΩ 2.62 κΩ 2.5 κΩ 2.39 κΩ 2.28 κΩ 2.18 κΩ 2.08 κΩ 1.99 κΩ 1.9 κΩ 1.82 κΩ 1.74 κΩ 1.66 κΩ 1.58 κΩ 1.51 κΩ 1.38 κΩ 1.26 κΩ 1.14 κΩ 1.04 κΩ 939 Ω 847 Ω 761 Ω 680 Ω 604 Ω 533 Ω 466 Ω 402 Ω 342 Ω 285 Ω 231 Ω 180 Ω 131 Ω 85 Ω 41 Ω Table 2-1; Preferred Values of R set for Standard Output Voltages Vout (Standard) 5V 3.3 V 2.5 V 2V 1.8 V 1.5 V 1.2 V Rset (Pref’d Value) 280 Ω 2 κΩ 4.32 κΩ 8.06 κΩ 11.5 κΩ 24.3 κΩ Open Vout (Actual) 5.009 V 3.294V 2.503 V 2.010V 1.801 V 1.506 V 1.200 V Figure 2-1; Vo Adjust Resistor Placement Vo Sense 13 12 11 6 Sense ATH26K12-9S PTH12030W VO 8, 9 VOUT GND 1, 3, 7 GND Adjust 10 5 RSET 1 %, 0.1 W COUT 330 µF (Optional) Notes: 1. Use a 0.1 W resistor. The tolerance should be 1 %, with temperature stability of 100 ppm/°C (or better). Place the resistor as close to the regulator as possible. Connect the resistor directly from pin 5 to pin 10 using dedicated PCB traces. 2. Never connect capacitors from Vo Adjust to either GND or Vout. Any capacitance added to the Vo Adjust pin will affect the stability of the regulator. GND GND North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662 Application Notes ATH26K12 Wide-Output Adjust Power Module (12-V Input) Features of the ATH Family of Non-Isolated Wide Output Adjust Power Modules Point-of-Load Alliance The ATH family of non-isolated, wide-output adjust power modules are optimized for applications that require a flexible, high performance module that is small in size. These products are part of the “Point-of-Load Alliance” (POLA), which ensures compatible footprint, interoperability and true second sourcing for customer design flexibility. The POLA is a collaboration between Texas Instruments, Artesyn Technologies, and Astec Power to offer customers advanced non-isolated modules that provide the same functionality and form factor. Product series covered by the alliance includes the ATH06 (6 A), ATH10 (10 A), ATH12/15 (12/15 A), ATH18/22 (18/22 A), and the ATH26/30 (26/30 A). From the basic, “Just Plug it In” functionality of the 6-A modules, to the 30-A rated feature-rich ATH30, these products were designed to be very flexible, yet simple to use. The features vary with each product. Table 3-1 provides a quick reference to the available features by product and input bus voltage. Table 3-1; Operating Features by Series and Input Bus Voltage ATH26K12 (26 A) products incorporate over-temperature shutdown protection. All of the products referenced in Table 3-1 include Auto-Track™. This is a feature unique to the ATH family, and was specifically designed to simplify the task of sequencing the supply voltage in a power system. These and other features are described in the following sections. Soft-Start Power Up The Auto-Track™ feature allows the power-up of multiple ATH modules to be directly controlled from the Track pin. However in a stand-alone configuration, or when the Auto-Track™ feature is not being used, the Track p in should be directly connected to the input voltage, Vin (see Figure 3-1). Figure 3–1 10 9 8 Track 5 Sense 6 Up Dn 12 V 2 3.3 V VIN PTH12020W ATH18K12-9S GND 1 7 Adjust 4 VO Inhibit 3 CIN 1,000 µF RSET, 2 k 0.1 W, 1 % Thermal Shutdown GND Margin Up/Down Pre-Bias Startup Output Sense On/Off Inhibit Auto-Track™ Over-Current Adjust (Trim) Series PTHxx050 ATH06 Input Bus 3.3 V / 5 V 12 V I OUT 6A 6A 10 A PTHxx060 ATH10 3.3 V / 5 V 12 V 10 A 8A 15 A 12 A 22 A 18 A 30 A 26 A PTHxx010 ATH12/15 3.3 V / 5 V 12 V PTHxx020 ATH18/22 3.3 V / 5 V 12 V PTHxx030 ATH26/30 3.3 V / 5 V 12 V • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • When the Track pin is connected to the input voltage the Auto-Track™ function is permanently disengaged. This allows the module to power up entirely under the control of its internal soft-start circuitry. When power up is under soft-start control, the output voltage rises to the set-point at a quicker and more linear rate. Figure 3–2 • • • • For simple point-of-use applications, the ATH06K12 (6 A) provides operating features such as an on/off inhibit, output voltage trim, and over-current protection. The ATH10K12 (10 A), and ATH12K12 (12 A) include an output voltage sense, and margin up/down controls. Then the higher output current, ATH18K12 (18 A) and HORIZ SCALE 5 ms/Div North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662 + + COUT 330 µF GND Vin (5 V/Div) Vo (1 V/Div) Iin (5 A/Div) Application Notes ATH26K12 Wide-Output Adjust Power Module (12-V Input) From the moment a valid input voltage is applied, the soft-start control introduces a short time delay (typically 5 ms-10 ms) before allowing the output voltage to rise. The output then progressively rises to the module’s setpoint voltage. Figure 3-2 shows the soft-start power-up characteristic of the 18-A output product (ATH18K12), operating from a 12-V input bus and configured for a 3.3-V output. The waveforms were measured with a 5-A resistive load and the Auto-Track™ feature disabled. The initial rise in input current when the input voltage first starts to rise is the charge current drawn by the input capacitors. Power-up is complete within 15 ms. the regulator to be turned off. The power modules function normally when the Inhibit pin is left open-circuit, providing a regulated output whenever a valid source voltage is connected to Vin with respect to GND. Figure 3-3 shows the typical application of the inhibit function. Note the discrete transistor (Q1). The Inhibit input has its own internal pull-up to Vin potential (12 V). The input is not compatible with TTL logic devices. An open-collector (or open-drain) discrete transistor is recommended for control. Figure 3–3 Vo Sense Over-Current Protection For protection against load faults, all modules incorporate output over-current protection. Applying a load that exceeds the regulator’s over-current threshold will cause the regulated output to shut down. Following shutdown a module will periodically attempt to recover by initiating a soft-start power-up. This is described as a “hiccup” mode of operation, whereby the module continues in a cycle of successive shutdown and power up until the load fault is removed. During this period, the average current flowing into the fault is significantly reduced. Once the fault is removed, the module automatically recovers and returns to normal operation. 10 9 8 5 VIN 2 ATH10K12-9S PTH12060W 3 1 7 4 6 VOUT CIN 560 µF 1 =Inhibit GND Q1 BSS138 RSET 2.0kΩ 1% 0.1 W COUT 330 µF Over-Temperature Protection (OTP) The ATH18K12 and ATH26K12 of products have overtemperature protection. These products have an on-board temperature sensor that protects the module’s internal circuitry against excessively high temperatures. A rise in the internal temperature may be the result of a drop in airflow, or a high ambient temperature. If the internal temperature exceeds the OTP threshold, the module’s Inhibit control is automatically pulled low. This turns the output off. The output voltage will drop as the external output capacitors are discharged by the load circuit. The recovery is automatic, and begins with a soft-start power up. It occurs when the the sensed temperature decreases by about 10 °C below the trip point. Note: The over-temperature protection is a last resort mechanism to prevent thermal stress to the regulator. Operation at or close to the thermal shutdown temperature is not recommended and will reduce the long-term reliability of the module. Always operate the regulator within the specified Safe Operating Area (SOA) limits for the worst-case conditions of ambient temperature and airflow. Turning Q1 on applies a low voltage to the Inhibit control pin and disables the output of the module. If Q1 is then turned off, the module will execute a soft-start power-up sequence. A regulated output voltage is produced within 20 msec. Figure 3-4 shows the typical rise in both the output voltage and input current, following the turn-off of Q1. The turn off of Q1 corresponds to the rise in the waveform, Q1 Vds. The waveforms were measured with a 5-A constant current load. Figure 3–4 Q1Vds (5 V/Div) Vo (2 V/Div) Output On/Off Inhibit For applications requiring output voltage on/off control, each series of the ATH family incorporates an output Inhibit control pin. The inhibit feature can be used wherever there is a requirement for the output voltage from HORIZ SCALE: 10 ms/Div Iin (2 A/Div) North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662 + + L O A D GND Application Notes ATH26K12 Wide-Output Adjust Power Module (12-V Input) Auto-Track™ Function The Auto-Track™ function is unique to the ATH family, and is available with the all “Point-of-Load Alliance” (POLA) products. Auto-Track™ was designed to simplify the amount of circuitry required to make the output voltage from each module power up and power down in sequence. The sequencing of two or more supply voltages during power up is a common requirement for complex mixed-signal applications, that use dual-voltage VLSI ICs such as DSPs, micro-processors, and ASICs. Figure 3-6 shows the output voltage waveforms from the circuit of Figure 3-5 after the On/Off Control is set from a high to a low-level voltage. The waveforms, Vo1 and Vo2 represent the output voltages from the two power modules, U1 (3.3 V) and U2 (2 V) respectively. Vo1 and Vo2 are shown rising together to produce the desired simultaneous power-up characteristic. The same circuit also provides a power-down sequence. Power down is the reverse of power up, and is accomplished by lowering the track control voltage back to zero volts. The important constraint is that a valid input voltage must be maintained until the power down is complete. It also requires that Q1 be turned off relatively slowly. This is so that the Track control voltage does not fall faster than Auto-Track's slew rate capability, which is 1 V/ms. The components R1 and C1 in Figure 3-5 limit the rate at which Q1 can pull down the Track control voltage. The values of 100 k-ohm and 0.1 µF correlate to a decay rate of about 0.17 V/ms. The power-down sequence is initiated with a low-to-high transition at the On/Off Control input to the circuit. Figure 3-7 shows the power-down waveforms. As the Track™ control voltage falls below the nominal set-point voltage of each power module, then its output voltage decays with all the other modules under Auto-Track™ control. How Auto-Track™ Works Auto-Track™ works by forcing the module’s output voltage to follow a voltage presented at the Track control pin. This control range is limited to between 0 V and the module’s set-point voltage. Once the track-pin voltage is raised above the set-point voltage, the module’s output remains at its set-point 1. As an example, if the Track pin of a 2.5-V regulator is at 1 V, the regulated output will be 1 V. But if the voltage at the Track pin rises to 3 V, the regulated output will not go higher than 2.5 V. When under track control, the regulated output from the module follows the voltage at its Track pin on a voltfor-volt basis. By connecting the Track pin of a number of these modules together, the output voltages will follow a common signal during power-up and power-down. The control signal can be an externally generated master ramp waveform, or the output voltage from another power supply circuit 3. For convenience the Track control incorporates an internal RC charge circuit. This operates off the module’s input voltage to produce a suitable rising waveform at power up. Notes on Use of Auto-Track™ 1. The Track pin voltage must be allowed to rise above the module’s set-point voltage before the module can regulate at its adjusted set-point voltage. 2. The Auto-Track™ function will track almost any voltage ramp during power up, and is compatible with ramp speeds of up to 1 V/ms. 3. The absloute maximum voltage that may be applied to the Track pin is the input voltage Vin. 4. The module will not follow a voltage at its Track control input until it has completed its soft-start initialization. This takes about 10 ms from the time that the module has sensed that a valid voltage has been applied its input. During this period, it is recommended that the Track pin be held at ground potential. 5. The module is capable of both sinking and sourcing current when following a voltage at its Track pin. Therefore startup into an output prebias cannot be supported when a module is under Auto-Track™ control. Note: A pre-bias holdoff is not necessary when all supply voltages rise simultaneously under the control of AutoTrack. 6. The Auto-Track™ function can be disabled by connecting the Track pin to the input voltage (Vin). When Auto-Track™ is disabled, the output voltage will rise at a quicker and more linear rate after input power is applied. **Auto-Track is a trademark of Texas Intruments, Inc. Typical Application The basic implementation of Auto-Track™ allows for simultaneous voltage sequencing of a number of AutoTrack™ compliant modules. Connecting the Track control pins of two or more modules forces the Track control of all modules to follow the same collective RC ramp waveform, and allows them to be controlled through a single transistor or switch; Q1 in Figure 3-5. To initiate a power-up sequence, it is recommended that the Track control be first pulled to ground potential. This should be done at or before input power is applied to the modules, and then held for at least 10 ms thereafter. This brief period gives the modules time to complete their internal soft-start initialization. Applying a logiclevel high signal to the circuit’s On/Off Control turns Q1 on and applies a ground signal to the Track pins. After completing their internal soft-start intialization, the output of all modules will remain at zero volts while Q1 is on. 10 ms after a valid input voltage has been applied to the modules, Q1 may be turned off. This allows the track control voltage to automatically rise toward to the modules' input voltage. During this period the output voltage of each module will rise in unison with other modules, to its respective set-point voltage. North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662 Application Notes ATH26K12 Wide-Output Adjust Power Module (12-V Input) Figure 3–5; Sequenced Power Up & Power Down Using Auto-Track U1 10 9 8 Track 5 6 12 V CIN + 2 VIN Inhibit 3 PTH12020W ATH18K12-9S GND 1 7 R2 2.0kΩ Vo1 =3.3 V + Vo2 =2 V + Vo1 (1 V/Div) Vo2 (1 V/Div) On/Off Control (5 V/Div) VO 4 COUT C1 0.1 µF U2 On/Off Control 1 = Power Down 0 = Power Up R1 100 k Q1 BSS138 2 VIN Inhibit 3 10 9 8 Track 5 6 PTH12010W ATH12K12-9S GND 1 7 R3 8k06 VO 0V CIN Figure 3–6; Simultaneous Power Up with Auto-Track™ Control Vo1 (1 V/Div) Vo2 (1 V/Div) On/Off Control (5 V/Div) HORIZ SCALE: 10 ms/Div North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 + 4 COUT Figure 3–7; Simultaneous Power Down with Auto-Track™ Control HORIZ SCALE: 10 ms/Div Asia (HK): 852-2437-9662 Application Notes ATH26K12 Wide-Output Adjust Power Module (12-V Input) Margin Up/Down Controls The ATH10K12, ATH12K12, ATH18K12, and ATH26K12 products incorporate Margin Up and Margin Down control inputs. These controls allow the output voltage to be momentarily adjusted 1, either up or down, by a nominal 5 %. This provides a convenient method for dynamically testing the operation of the load circuit over its supply margin or range. It can also be used to verify the function of supply voltage supervisors. The ±5 % change is applied to the adjusted output voltage, as set by the external resistor, Rset at the Vo Adjust pin. The 5 % adjustment is made by pulling the appropriate margin control input directly to the GND terminal 2. A low-leakage open-drain device, such as an n-channel MOSFET or p-channel JFET is recommended for this purpose 3. Adjustments of less than 5 % can also be accommodated by adding series resistors to the control inputs. The value of the resistor can be selected from Table 3-2, or calculated using the following formula. Notes: 1. The M argin Up* a nd M argin Dn* c ontrols were not intended to be activated simultaneously. If they are their affects on the output voltage may not completely cancel, resulting in the possibility of a slightly higher error in the output voltage set point. 2. The ground reference should be a direct connection to the module GND at pin 7 (pin 1 for the ATH06). This will produce a more accurate adjustment at the load circuit terminals. The transistors Q1 and Q2 should be located close to the regulator. 3. The Margin Up and Margin Dn control inputs are not compatible with devices that source voltage. This includes TTL logic. These are analog inputs and should only be controlled with a true open-drain device (preferably a discrete MOSFET transistor). The device selected should have low off-state leakage current. Each input sources 8 µA when grounded, and has an open-circuit voltage of 0.8 V. Up/Down Adjust Resistance Calculation To reduce the margin adjustment to something less than 5 %, series resistors are required (See RD and RU i n Figure 3-8). For the same amount of adjustment, the resistor value calculated for RU and RD will be the same. The formulas is as follows. R U o r RD = 499 ∆% – 99.8 kΩ Table 3-2; Margin Up/Down Resistor Values % Adjust 5 4 3 2 1 RU / RD 0.0 kΩ 24.9 kΩ 66.5 kΩ 150.0 kΩ 397.0 kΩ Where ∆% = The desired amount of margin adjust in percent. Figure 3–8; Margin Up/Down Application Schematic 10 1 9 8 7 +Vo 0V VIN PTH12010W ATH12K12-9S (Top View) 2 3 4 5 6 +VOUT + Cin MargDn RD RU RSET 0.1 W, 1 % + Cout L O A D Q1 Q2 MargUp GND GND North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662 Application Notes ATH26K12 Wide-Output Adjust Power Module (12-V Input) Pre-Bias Startup Capability The ATH26K12 power module is capable of safely powering up while a voltage is applied to its output from an external source. A pre-bias startup condition can occur in complex digital systems when current from another power source backfeeds through a dual-supply logic component, such as an FPGA or ASIC. Another path might be via clamp diodes as part of a dual-supply power-up sequencing arrangement. The prebias condition can cause problems with power modules that incorporate synchronous rectifiers. This is because under most operating conditions, these types of modules can sink as well as source output current. Although the ATH26K12 power module incorporates synchronous rectifiers it will not sink current during startup 1, or whenever the Inhibit pin is held low. However, to ensure satisfactory operation of this function, certain conditions must be maintained. 2 Figure 3-9 shows an application circuit that applies an external bias voltage to a ATH26K12 during startup. The supply voltage superviser, U1, holds the output of the module off via its Inhibit pin until the voltage, V1 (3.3 V), has first been applied to the ASIC. As V1 rises, some of the voltage appears at the module’s output. The start-up waveforms are shown in Figure 3-10. Note that the output current from the ATH26K12 (I2) shows no negative current until it raises the output voltage to full regulation (2.5 V). Note: The pre-bias start-up feature is not compatible with Auto-Track™. When the module is under Auto-Track™ control, it will sink current if the output voltage is below that of a back-feeding source. To ensure a pre-bias hold-off the Auto-Track™ function must either be disabled 3, or the module’s output held off (for at least 50 ms) using the Inhibit pin. Either approach ensures that the Track pin voltage is above the setpoint voltage at start up. HORIZ SCALE: 5 ms/Div Notes 1. Startup includes the short delay (approx. 10 ms) prior to the output voltage rising, followed by the rise of the output voltage under the module’s internal soft-start control. Startup is complete when the output voltage has risen to either the setpoint voltage or the voltage at the Track pin, whichever is lowest. 2. To ensure that the regulator does not sink current when power is first applied (even with a ground signal applied to the Inhibit control pin), the input voltage must always be greater than the output voltage throughout the power-up and power-down sequence. 3. The Auto-Track™ function can be disabled at power up by immediately applying a voltage to the module’s Track pin that is greater than its set-point voltage. This can be easily accomplished by connecting the Track pin to Vin. Figure 3–10; Pre-Bias Startup Waveforms V 1 (1 V/Div) V2 (1 V/Div) I 2 (5 A/Div) Figure 3–9; Application Circuit Demonstrating Pre-Bias Startup V1 = 3.3 V 13 12 11 6 Sense Margin Margin Track Up Down VIN = 12 V 2 VIN PTH12030W ATH26K12-9S Inhibit GND 4 1, 3, 7 GND Adjust 10 5 VO 8, 9 V2 = 2.5 V 0V I2 U1 TPS3838K33 C1 330 µF R1 4k32 C2 330 µF VCORE VCCIO 5 1 3 2 C3 0.1 µF 4 ASIC North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662 Application Notes ATH26K12 Wide-Output Adjust Power Module (12-V Input) Remote Sense The ATH10K12, ATH12K12, ATH18K12, and ATH26K12 products incorporate an output voltage sense pin, Vo Sense. The Vo Sense pin should be connected to Vout at the load circuit (see data sheet standard application). A remote sense improves the load regulation performance of the module by allowing it to compensate for any ‘IR’ voltage drop between itself and the load. An IR drop is caused by the high output current flowing through the small amount of pin and trace resistance. Use of the remote sense is optional. If not used, the V o Sense pin can be left open-circuit. An internal low-value resistor (15-Ω or less) is connected between the Vo Sense and Vout. This ensures the output voltage remains in regulation. With the sense pin connected, the difference between the voltage measured directly between the Vout and GND pins, and that measured from V o Sense t o GND, is the amount of IR drop being compensated by the regulator. This should be limited to a maximum of 0.3 V. Note: The remote sense feature is not designed to compensate for the forward drop of non-linear or frequency dependent components that may be placed in series with the converter output. Examples include OR-ing diodes, filter inductors, ferrite beads, and fuses. When these components are enclosed by the remote sense connection they are effectively placed inside the regulation control loop, which can adversely affect the stability of the regulator. North America (USA): 1-888-41-ASTEC Europe (UK): 44(1384)842-211 Asia (HK): 852-2437-9662