For assistance or to order, call (800) 531-5782 Revised 1/12/99 PT7750 Series Application Notes Mechanical Outline Product Selector Guide 15 AMP 24V INPUT “BIG-HAMMER III” PROGRAMMABLE ISR The PT7750 series is a new +24V input, 15 Amp output, high-performance Integrated Switching Regulator (ISR) housed in a 27-pin SIP package. The 15A capability allows easy integration of the latest high-speed, low-voltage µPs and bus drivers into +24V distributed power systems. The PT7750 series has been designed to work in parallel with one or more of the PT7747 current boosters for increased Iout in increments of 15A. The output voltage of the PT7750 series can be easily programmed over a wide range with a 5-bit input. A differential remote sense is provided which automatically compensates for any voltage drop from the ISR to the load. 2000µF of output capacitance is required for proper operation. Pin-Out Information Standard Application PROGRAMMING PINS VID0 VID1 VID2 VID3 VID4 VIN REMOTE SENSE (+) 6 4 3 2 1 L1 PT7750 7 - 11 1µH CIN + 26 27 13 - 19 5 VOUT 20 - 25 12 COUT + LOAD SYNC OUT GND GND STBY* REMOTE SENSE (-) Cin = Required 560µF electrolytic (See input filter note) C out = Required 2000µF electrolytic L1 = Optional 1µH input choke Features Pin Function Pin Function 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Remote Sense Vout 27 Sync Out VID0 VID1 VID2 VID3 STBY* - Stand-by VID4 Vin Vin Vin Vin Vin Remote Sense Gnd GND For STBY* pin: open = output enabled ground = output disabled. • +24V bus input • High Efficiency • Differential Remote Sense • 27-pin SIP Package • Parallelable with PT7747 15A current boosters GND GND GND GND GND GND Vout Vout Vout Vout Vout Vout Specifications PT7750 SERIES Characteristics (Ta = 25°C unless noted) Symbols Conditions Min Typ Max Units Output Current Io Ta = +60°C, 200 LFM Ta = +25°C, natural convection 0.1 * 0.1 * — — 15** 15** A A Input Voltage Range Vin 0.1A ≤ Io ≤ Io max 20.0 — 28.0 V Undervoltage Lockout Threshold Vuvl 0.1A ≤ Io ≤ Io max — 18.7 — V Output Voltage Tolerance ∆Vo Vin = +24V, Io = 15A PT7751 0°C ≤ Ta ≤ +55°C PT7756 — — — — ±80 ±160 mV mV Line Regulation Regline 20V ≤ Vin ≤ 28V, Io = Io max (w/remote sense) — ±15 — mV Load Regulation Regload Vin = +24V, 0.1 ≤ Io ≤ Io max (w/remote sense) — ±10 — mV Vo Ripple/Noise Vn Vin = +24V, Io = Io max — 75 — mV Transient Response with Cout = 2000µF t tr Vos Io step between 7.5A and 15A Vo over/undershoot — — 100 200 — — µSec mV — — — 88 84 80 — — — % % % 300 350 400 kHz 0 — +85 °C °C Efficiency η Switching Frequency ƒo Absolute Maximum Operating Temperature Range Ta Recommended Operating Temperature Range Ta Forced Air Flow = 200 LFM At Vin = +24V, Io = 12A 0 — +65*** Storage Temperature Ts — -40 — +125 °C Weight — Vertical/Horizontal — 53/66 — grams Vin = +24V, Io = 10A 20V ≤ Vin ≤ 28V 0.1A ≤ Io ≤ 15A Vo = 5.0V Vo = 3.3V Vo = 2.5V * ISR-will operate down to no load with reduced specifications. Please note that this product is not short-circuit protected. ** The PT7750 series can be easily paralleled with one or more of the PT7747 Current Boosters to provide increased output current in increments of 15A. *** See safe operating area chart. Output Capacitors: The PT7750 series requires a minimum output capacitance of 2000µF for proper operation. Do not use Oscon type capacitors. The maximum allowable output capacitance is (42,000 ÷ Vout)µF for the PT7751, (96,000 ÷ Vout)µF for the PT7756, or 15,000µF, whichever is less. Input Filter: An input inductor is optional for most applications. The input inductor must be sized to handle 9ADC with a typical value of 1µH. The input capacitance must be rated for a minimum of 8.0 Arms of ripple current when operated at maximum output current and maximum output voltage. Contact an applications engineer for input capacitor selection for applications at other output voltages and output currents. 56 Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com For assistance or to order, call (800) 531-5782 PT7750 Series Programming Information Ordering Information PT7751 VID3 VID2 VID1 VID0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V 3.4V 3.5V 3.6V 3.7V 3.8V 3.9V 4.0V 4.1V 4.2V 4.3V 4.4V 4.5V 4.6V 4.7V 4.8V 4.9V 5.0V 5.1V 5.2V 5.3V 5.4V 5.5V 5.6V 6.6V 6.8V 7.0V 7.2V 7.4V 7.6V 7.8V 8.0V 8.2V 8.4V 8.6V 8.8V 9.0V 9.2V 9.4V 9.6V (For dimensions and PC board layout, see Package Styles 1000 and 1010.) 9.8V 10.0V 10.2V 10.4V 10.6V 10.8V 11.0V 11.2V 11.4V 11.6V 11.8V 12.0V 12.2V 12.4V 12.6V 12.8V PT Series Suffix (PT1234X) Case/Pin Configuration Vertical Through-Hole Horizontal Through-Hole Horizontal Surface Mount N A 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. C H A R A C T E R I S T I C PT7751 Safe Operating Area (@Vin=+24V, Over Vo Range) 100 90 90 80 Vout 80 12.0V 5.0V 70 3.3V 2.5V 60 50 Ambient Temperature (°C) Efficiency (%) Efficiency vs Output Current (@Vin=+24V) D A T A 40 Recommended Maximum Operating Temperature 70 Airflow Nat conv 60 60LFM 120LFM 50 200LFM 40 30 20 0 3 6 9 12 0 15 3 Output Current (A) Ouput Ripple vs Output Current (@Vin=+24V) 9 12 15 PT7756 Safe Operating Area (@Vin=+24V, Over Vo Range) 90 60 80 Vout 12.0V 40 5.0V 3.3V 30 2.5V 20 10 Ambient Temperature (°C) 70 50 Riplle (mV) 6 Output Current (A) Recommended Maximum Operating Temperature 70 Airflow Nat conv 60 60LFM 120LFM 50 200LFM 40 30 20 0 0 3 6 9 12 0 15 3 6 9 12 15 Output Current (A) Output Current (A) Power Dissipation vs Output Current (@Vin=+24V) 16 14 Pd (Watts) 12 Vout 10 12.0V 5.0V 8 3.3V 2.5V 6 4 2 0 0 3 6 9 12 15 Output Current (A) Note: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures. Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com 57 DATA SHEETS 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 VID4=1 VID4=0 VID4=1 VID4=0 Vout Vout Vout Vout 24V Bus Products 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 PT7751❏ ❏ = 2.5 to 5.6 Volts ❏ = 6.6 to 12.8 Volts PT7756❏ PT7756 For assistance or to order, call Application Notes (800) 531-5782 PT7750 Series More Application Notes Pin-Coded Output Voltage Adjustment on the “Big Hammer III” 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. Power Trends PT7750 series ISRs incorporating pin-coded voltage control, use pins 1, 2, 3, 4, & 6 to adjust the ouput voltage. The control pins are identified VID0 - VID4 respectively. When the control pins are left open-circuit, the ISR output will regulate at its factory trimmed output voltage. Each control pin is internally connected to a precision resistor, and when grounded increases the output voltage by a set amount. The internal resistors are binary code weighted, allowing the output voltage of the ISR to be programmed as a function of a binary code. VID0 represents the LSB, and VID4 the MSB (or range change bit). The output voltage ranges offered by these regulators are compatible with some microprocessors, and provide a convenient method of output voltage selection for many other applications. Refer to Figure 1 below for the connection schematic, and the PT7750 Data Sheet for the 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 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 set-point. 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 power-up, 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 soft-start power-up to the programmed voltage. Notes: 1. The programming convention is as follows:Logic 0: Logic 1: Connect to pin12 (Remote Sense Ground). 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 4 3 2 1 26 VID4 - VID0 +24V 7-11 1µ H (Optional) SNS(+) PT7750 Vin STBY 5 Synch Out 27 GND 13-19 20-25 Vo SNS(-) 12 + Cin + Cout L O A D STBY COM Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com 3