BD3537F-E2

TECHNICAL NOTE High-performance Regulator IC Series for PCs Termination Regulators for DDR-SDRAMs BD3537F Description BD3537F is a termination regulator compatible with JEDEC DDR-SDRAM, which functions as a linear power supply incorporating an N-channel MOSFET and provides a sink/source current capability up to 1.8A respectively. A built-in high-speed OP-AMP specially designed offers an excellent transient response. Requires 5.0 volts as a bias power supply to drive the N-channel MOSFET. For BD3537F, ceramic capacitor can be used as output capacitor. Thus, the BD3537F is designed to enable significant package profile downsizing as the total regulator part. Features 1) Incorporates a push-pull power supply for termination (VTT) 2) Incorporates an enabler 3) Incorporates an undervoltage lockout (UVLO) 4) Employs SOP8 package 5) Incorporates a thermal shutdown protector (TSD) 6) Compatible with Dual Channel (DDR-II) 7) Operates with input voltage from 4.75 to 5.25 volts 8) Incorporates soft start function Use Power supply for DDR I/II - SDRAM Oct. 2008 ●ABSOLUTE MAXIMUM RATINGS Parameter Symbol Limits Unit VCC 7 *1 V REF *1 V 7 *1 V Input Voltage REF Input Voltage Termination Input Voltage 7 VTT_IN Output Current ITT 3 A Power Dissipation1 Pd1 560 *2 mW Power Dissipation2 Pd2 690 *3 mW Operating Temperature Range Topr -30～+100 ℃ Storage Temperature Range Tstg -55～+150 ℃ Tjmax +150 ℃ Maximum Junction Temperature *1 Should not exceed Pd. *2 Reduced by 4.48mW for each increase in Ta of 1℃ over 25℃ (no heat sink). *3 Reduced by 5.52mW for each increase in Ta of 1℃ over 25℃ (when mounted on 70mm x 70mm x 1.6mm Glass-epoxy PCB). ●OPERATING CONDITIONS (Ta=25℃) Parameter Input Voltage Termination Input Voltage Reference Voltage Symbol MIN MAX Unit VCC 4.75 5.25 V VTT_IN 1.746 1.854 V VEN 0.6 1.6 V ★ No radiation-resistant design is adopted for the present product. ●ELECTRICAL CHARACTERISTICS (unless otherwise noted, Ta=25℃, VCC=5V, REF=0.9V, VTT_IN=1.8V) Standard Value Parameter Symbol Unit Condition MIN TYP MAX Standby Current IST - 50 90 uA REFTerminal A>Terminal B, or ・a parasitic transistor if the electric potentials at the terminals satisfy the following relationship; Terminal B>GND Terminal A. The structure of the IC inevitably forms parasitic elements, the activation of which may cause interference among circuits, and/or malfunctions contributing to breakdown. It is therefore requested to take care not to use the device in such manner that the voltage lower than GND (at P-substrate) may be applied to the input terminal, which may result in activation of parasitic elements. Resistor Transistor (NPN) Pin A Pin B C Pin B B E Pin A N P+ N P+ P N N Parasitic element P+ P substrate Parasitic element GND B N P+ P N C E Parasitic element P substrate Parasitic element 7/10 GND GND GND Other adjacent elements 10. GND wiring pattern When both a small-signal GND and high current GND are present, single-point grounding (at the set standard point) is recommended, in order to separate the small-signal and high current patterns, and to be sure the voltage change stemming from the wiring resistance and high current does not cause any voltage change in the small-signal GND. In the same way, care must be taken to avoid wiring pattern fluctuations in any connected external component GND. 11. Output capacitor (C3) Do not fail to connect a output capacitor to VTT output terminal for stabilization of output voltage. The capacitor connected to VTT output terminal works as a loop gain phase compensator. Insufficient capacitance may cause an oscillation. It is recommended to connect a 10 μF ceramic capacitor (X5R or X7R) near to VTT and GND, though it depends on ambient temperature and other conditions. A low ESR ceramic capacitor may reduce a loop gain phase margin and may cause an oscillation, which may be improved by connecting a resistor in series with the OS-capacitor (several-hundred μF). It is therefore requested to carefully check under the actual temperature and load conditions to be applied. 12. Input capacitors (C1 and C2) These input capacitors are used to reduce the output impedance of power supply to be connected to the input terminals (VCC and VTT_IN). Increase in the power supply output impedance may result in oscillation or degradation in ripple rejecting characteristics. It is recommended to use a low temperature coefficient 1μF (for VCC) and 10μF (for VTT_IN) capacitor, but it depends on the characteristics of the power supply input, and the capacitance and impedance of the pc board wiring pattern. It is therefore requested to carefully check under the actual temperature and load conditions to be applied. 13. Input terminals (VCC, VTT_IN and REF) VCC, VTT_IN and REF terminals of this IC are made up independent one another. To VCC terminal, the UVLO function is provided for malfunction protection. REF pin includes the Enable circuit. Irrespective of the input order of the inputs terminals, VTT output is activated to provide the output voltage when UVLO voltages reach the threshold voltage while REF voltage reaches the threshold of EN pin. 14.REF pin (R1 , R2 , C4) REF pin controls this IC’s status ON or OFF. When REF voltage reaches EN-ON voltage, the output voltage operates. Then BD3537F does not include “soft start function” so set the start up time by the value of extra components R1, R2 and C4. 15. Operating range Within the operating range, the operation and function of the circuits are generally guaranteed at an ambient temperature within the range specified. The values specified for electrical characteristics may not be guaranteed, but drastic change may not occur to such characteristics within the operating range. 16. Allowable loss Pd For the allowable loss, the thermal derating characteristics are shown in the Exhibit, which should be used as a guide. Any uses that exceed the allowable loss may result in degradation in the functions inherent to IC including a decrease in current capability due to chip temperature increase. Use within the allowable loss. 17. Built-in thermal shutdown protection circuit Thermal shutdown protection circuit is built-in to prevent thermal breakdown. Turns VTT output to OFF when the thermal shutdown protection circuit activates. This thermal shutdown protection circuit is originally intended to protect the IC itself. It is therefore requested to conduct a thermal design not to exceed the temperature under which the thermal shutdown protection circuit can work. 18. The use in the strong electromagnetic field may sometimes cause malfunction, to which care must be taken. In the event that load containing a large inductance component is connected to the output terminal, and generation of back-EMF at the start-up and when output is turned OFF is assumed, it is requested to insert a protection diode. 19. In the event that load containing a large inductance component is (Example) connected to the output terminal, and generation of back-EMF at the OUTPUT PIN start-up and when output is turned OFF is assumed, it is requested to insert a protection diode. 20. We are certain that examples of applied circuit diagrams are recommendable, but you are requested to thoroughly confirm the characteristics before using the IC. In addition, when the IC is used with the external circuit changed, decide the IC with sufficient margin provided while consideration is being given not only to static characteristics but also variations of external parts and our IC including transient characteristics. 8/10 ●POWER DISSIPATION ◎SOP8(BD3537F) [mW] 700 Power Dissipation [Pd] 600 (1) 690mW (1) 70mm×70mm×1.6mm Glass-epoxy PCB θj-c=181℃/W (2) With no heat sink θj-a=222℃/W 500 (2) 560mW 400 100℃ 300 200 100 0 0 25 50 75 100 125 150 [℃] Ambient Temperature [Ta] ●Ordering part number B D 3 5 3 7 F Package Type Part Number E ― 2 E2 Emboss tape reel Pin 1 opposite draw-out side ・F : SOP8 ・BD3537 SOP8 1 4 1234 1234 1234 1Pin 1234 (Unit:mm) 1234 Reel 1234 1234 1.27 0.4±0.1 E2 (The direction is the 1pin of product is at the upper left when you hold reel on the left hand and you pull out the tape on the right hand) 0.15±0.1 0.1 1234 1.5±0.1 0.11 6.2±0.3 4.4±0.2 0.3Min. 5 Embossed carrier tape 2500pcs Direction of feed 5.0±0.2 8 Tape Quantity Direction of feed ※When you order , please order in times the amount of package quantity. 9/10 10/10 Catalog No.08T425A '08.10 ROHM © Appendix Notes No copying or reproduction of this document, in part or in whole, is permitted without the consent of ROHM CO.,LTD. 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