PT7705—5V 18 Amp “Big-Hammer” Programmable Integrated Switching Regulator SLTS045A (Revised 6/30/2000) The PT7705 is a series of highperformance, 18 Amp Integrated Switching Regulators (ISRs) housed in a 27-pin SIP package. The 18A capability allows easy integration of the latest high-speed, low-voltage µPs and bus drivers into existing 5V systems. The PT7705 series has been designed to work in parallel with one or more of the PT7749 - 18A current boosters for increased Iout in incre- Pin-Out Information Standard Application PROGRAMMING PINS VID0 VID1 VID2 VID3 VID4 V IN REMOTE SENSE (+) 6 4 3 2 1 L1 1µH 27 + 26 PT7705 7 - 11 C IN 13 - 19 5 VOUT 20 - 25 12 C OUT + LOAD SYNC OUT GND GND STBY* REMOTE SENSE (-) Specifications ments of 18A. The output voltage of the PT7705 can be easily programmed from 1.3V to 3.5V with a 5 bit input compatible with Intel’s Pentium II Processor. A differential remote sense is also provided which automatically compensates for any voltage drop from the ISR to the load. 1200µF of output capacitance are required for proper operation. Cin = Required 1200µF electrolytic Cout= Required 1200µF electrolytic L1 = Optional 1µH input choke Pin Function Pin Function Pin Function 1 VID0 10 Vin 18 GND 2 VID1 11 Vin 19 GND 3 VID2 12 Remote Sense Gnd 20 Vout 4 5 VID3 STBY* - Stand-by 13 14 GND GND 21 22 Vout Vout 6 VID4 15 GND 23 Vout 7 Vin 16 GND 24 Vout 8 9 Vin Vin 17 GND 25 26 Remote Sense Vout 27 Sync Out For STBY* pin; open = output enabled ground = output disabled. Vout PT7705 SERIES Characteristics (Ta = 25°C unless noted) Symbols Conditions Min Typ Max Units Output Current Io Ta = +60°C, 200 LFM, pkg N Ta = +25°C, natural convection 0.1 (1) 0.1 (1) — — 18 (2) 15 (2) A Input Voltage Range Vin 0.1A ≤ I o ≤ 15A 4.5 — 5.5 V Output Voltage Tolerance ∆Vo Vin = +5V, Io = 15A 0°C ≤ Ta ≤ +65°C Vo-0.03 — Vo+0.03 V Line Regulation Regline 4.5V ≤ V in ≤ 5.5V, I o = 15A — ±10 — mV Load Regulation Regload Vin = +5V, 0.1 ≤ Io ≤ 15A — ±10 — mV (3) Vo Ripple/Noise Vn Vin = +5V, Io = 15A — 50 — mV Transient Response with Cout = 1200µF ttr Vos Io step between 7.5A and 15A Vo over/undershoot — — 100 200 — — µSec mV Efficiency η Vin = +5V, Io = 10A — — — — — 89 87 85 79 77 — — — — — % Vo Vo Vo Vo Vo = = = = = 3.3V 2.9V 2.5V 1.8V 1.5V Switching Frequency ƒo 4.5V ≤ V in ≤ 5.5V 0.1A ≤ I o ≤ 15A 650 700 750 Absolute Maximum Operating Temperature Range Ta Over V in Range 0 — +85 Storage Temperature Ts — -40 — +125 kHz (4) °C °C Mechanical Shock Per Mil-STD-883D, Method 2002.3 1 msec, Half Sine, mounted to a fixture — 500 — G’s Mechanical Vibration Per Mil-STD-883D, Method 2007.2, 20-2000 Hz, Soldered in a PC board — 10 — G’s Vertical/Horizontal — 31/41 — grams Weight Notes: (1) (2) (3) (4) — ISR will operate down to no load with reduced specifications. Please note that this product is not short-circuit protected. The PT7705 series can be easily paralleled with one or more of the PT7749 Current Boosters to provide increased output current in increments of 18A. The minimum input voltage is 4.5V or Vout+1.2V, whichever is greater. See SOA curves or consult the factory for the appripriate derating. Output Capacitors: The PT7705 series requires a minimum ouput capacitance of 1200µF for proper operation. Do not use Oscon type capacitors. The maximum allowable output capacitance is 15,000µF. See Capacitor Application Note. Input Filter: An input filter is optional for most applications. The input inductor must be sized to handle 15ADC with a typical value of 1µH. The input capacitance must be rated for a minimum of 1.3Arms of ripple current. For transient or dynamic load applications, additional capacitance may be required. For technical support and more information, see inside back cover or visit www.ti.com/powertrends PT7705—5V 18 Amp “Big-Hammer” Programmable Integrated Switching Regulator Ordering Information Programming Information Features • Single-Device: +5V input • 5-bit Programmable: 1.3V to 3.5V@18A • High Efficiency • Input Voltage Range: 4.5V to 5.5V • Differential Remote Sense • 27-pin SIP Package • Parallelable with PT7749 18A “Current Boosters” VID3 VID2 VID1 VID0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 PT7705o = 1.3 to 3.5 Volts VID4=1 VID4=0 Vout Vout 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 2.0V 2.1V 2.2V 2.3V 2.4V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V 3.4V 3.5V (For dimensions and PC board layout, see Package Styles 800 and 810.) 1.30V 1.35V 1.40V 1.45V 1.50V 1.55V 1.60V 1.65V 1.70V 1.75V 1.80V 1.85V 1.90V 1.95V 2.00V 2.05V PT Series Suffix (PT1234X) Case/Pin Configuration Vertical Through-Hole N Horizontal Through-Hole A Horizontal Surface Mount C Logic 0 = Pin 12 potential (remote sense gnd) Logic 1 = Open circuit (no pull-up resistors) VID3 and VID4 may not be changed while the unit is operating. T Y P I C A L PT7705, Vo = 3.3 VDC C H A R A C T E R I S T I C S PT7705, Vo = 3.3 VDC (See Note B) Safe Operating Area Curves (@Vin=+5V) (See Note A) Efficiency vs Output Current 100 PKG SUFFIX N Ambient Temperature (°C) 80 70 Airflow Nat Conv 60 Efficiency - % 90 90 80 Vin 4.5V 70 5.0V 5.5V 60 60LFM 100LFM 50 50 200LFM 40 40 0 30 3 6 9 12 15 18 Iout-(Amps) 20 0 2 4 6 8 10 12 14 16 18 Ripple vs Output Current Output Current (Amps) 60 PKG SUFFIX A, C 50 Vin 40 80 Airflow 70 Nat Conv 60LFM 60 Ripple-(mV) Ambient Temperature (°C) 90 100LFM 50 5.5V 30 5.0V 4.5V 20 10 200LFM 0 40 0 3 30 6 9 12 15 18 Iout-(Amps) 20 0 2 4 6 8 10 12 14 16 18 Power Dissipation vs Output Current Output Current (Amps) 14 PD-(Watts) 12 10 Vin 5.5V 8 5.0V 4.5V 6 4 2 0 0 3 6 9 12 15 18 Iout-(Amps) Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the ISR. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures. For technical support and more information, see inside back cover or visit www.ti.com/powertrends Application Notes PT7705/7706 Series Pin-Coded Output Voltage Adjustment on the “Big Hammer” Series ISRs 4. If active devices are used to ground the voltage control pins, low-level open drain MOSFET devices should be used over bipolar transistors. The inherent Vce(sat) in bipolar devices introduces errors in the device’s internal divider network. Discrete transistors such as the BSS138, 2N7002, IRLML2402, or the 74C906 hex open-drain buffer are examples of appropriate devices. The ISRs related to Power Trends’ PT7705 incorporate pin-coded voltage control to adjust the ouput voltage. The control pins are identified VID0 - VID4 (pins 1, 2, 3, 4, & 6) respectively. When the control pins are left open-circuit, the ISR output will regulate at its factory trimmed output voltage. Each pin is internally connected to a precision resistor, which when grounded changes the output voltage by a set amount. By selectively grounding VID0 -VID4, the output voltage these ISRs can be programmed in incremental steps over the specified output voltage range. In each case, the program code and output voltage range offered by these ISRs are compatible with the voltage ID specification defined by Intel Corporation for voltage regulator modules (VRMs) used to power Pentium® microprocessors. Refer to Figure 1 below for the connection schematic, and the respective device Data Sheet for the appropriate programming code information. Active Voltage Programming: Special precautions should be taken when making changes to the voltage control progam code while the unit is powered. It is highly recommended that the ISR be either powered down or held in standby. Changes made to the program code while Vout is enabled induces high current transients through the device. This is the result of the electrolytic output capacitors being either charged or discharged to the new output voltage setpoint. The transient current can be minimized by making only incremental changes to the binary code, i.e. one LSB at a time. A minimum of 100µs settling time between each program state is also recommended. Making non-incremental changes to VID3 and VID4 with the output enabled is discouraged. If they are changed, the transients induced can overstress the device resulting in a permanent drop in efficiency. If the use of active devices prevents the program code being asserted prior to powerup, pull pin 5 (STBY) to the device GND during the period that the input voltage is applied to Vin. Releasing pin 5 will then allow the device output to execute a softstart power-up to the programmed voltage. Notes: 1. The programming convention is as follows:Logic 0: Connect to pin12 (Remote Sense Ground). Logic 1: Open circuit/open drain (See notes 2, & 4) 2. Do not connect pull-up resistors to the voltage programming pins. 3. To minimize output voltage error, always use pin 12 (Remote Sense Ground) as the logic “0” reference. While the regular ground (pins 13-19) can also be used for programming, doing so will degrade the load reglation of the product. Figure 1 6 +5V 7-11 1µH (Optional) 4 3 2 1 VID4 - VID0 26 SNS(+) PT7705 Vin STBY 5 Synch Out 27 GND 13-19 Vo 20-25 SNS(-) 12 + Cin STBY COM For technical support and more information, see inside back cover or visit www.ti.com/powertrends + Cout L O A D Application Notes PT7705/7706 Series Using the Standby Function on the “Big Hammer” Programmable ISR Series For applications requiring output voltage On/Off control, the PT7705 “Big Hammer” ISRs incorporate a standby function1 . This feature may be used for power-up/shutdown sequencing, and to change the output voltage while input power is applied. See related notes: “Pin-coded Output Voltage Adjustment on the ‘Big Hammer’ Series ISRs.” The standby function is provided by the STBY* control, pin 5. If pin 5 is left open-circuit the regulator operates normally, providing a regulated output whenever a valid supply voltage is applied to Vin (pins 7-11) with respect to GND (pins 13-19). Connecting pin 5 to ground 2 will set the regulator output to zero volts3 . This places the regulator in standby mode, and reduces the input current to typcially 45mA (75mA max). If a ground signal is applied to pin 5 prior to power-up, the regulator output will be held at zero volts during the period that input power is applied. The standby input must be controlled with an opencollector (or open-drain) discrete transistor (See Figure 1). Table 1 gives the threshold requirements. Table 1 Inhibit Control Threshold 2 Parameter Min Max Disable (VIL) –0.1V 0.3V Notes: 1. The Standby/Inhibit control logic is similar for all Power Trends’ modules, but the flexibility and threshold tolerances will be different. For specific information on this function for other regulator models, consult the applicable application note. 2. The Standby input on the PT7705 regulator series must be controlled using an open-collector (or open-drain) discrete transistor. Do Not use a pull-up resistor. The control input has an open-circuit voltage of about 1.5Vdc. To set the regulator output to zero, the control pin must be “pulled” to less than 0.3Vdc with a low-level 0.1mA sink to ground. 3. When placed in the standby mode, the regulator output discharges the output capacitance with a low impedance to ground. If an external voltage is applied to the output, it will sink current and possibly over-stress the part. 4. The turn-off time of Q1, or rise time of the standby input is not critical on the PT7705 series. Turning Q1 off slowly, over periods up to 100ms, will not affect regulator operation. However, a slow turn-off time will increase both the initial delay and rise-time of the output voltage. Figure 1 6 4 3 2 1 26 VID4 - VID0 7-11 5V Rem Sns (+) 20-25 PT7705 Vin Synch STBY Out 27 5 GND V o =2.5V Vo Rem Sns (–) 13-19 12 + L O A D + C in C out Q1 BSS138 Inhibit COM COM Turn-On Time: Turning Q1 in Figure 1 off, removes the lowvoltage signal at pin 5 and enables the output. Following a brief delay of 5-10ms, the output voltage of the PT7705 series regulators rise to full regulation within 15ms4 . Figure 2 shows the typical output voltage waveform of a PT7705 following the prompt turn-off of Q1 at time t =0 secs. The output voltage in Figure 1 is set to 2.5V by connecting VID0 (pin 1), and VID2 (pin 3) to the Remote Sense Gnd (pin 12)*. The waveform in Figure 2 was measured with a 5V input source voltage, and 10A resistive load. Figure 2 Vo (2V/Div) Iin (5A/Div) 0 5 10 15 20 25 t (milli - secs) * Consult the data sheet for details on other VID codes. For technical support and more information, see inside back cover or visit www.ti.com/powertrends IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. 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