Datenblatt-Suchmaschine für elektronische Bauteile |
|
MC34716EP Datenblatt(PDF) 11 Page - Freescale Semiconductor, Inc |
|
MC34716EP Datenblatt(HTML) 11 Page - Freescale Semiconductor, Inc |
11 / 25 page Analog Integrated Circuit Device Data Freescale Semiconductor 11 34716 FUNCTIONAL DESCRIPTION INTRODUCTION FUNCTIONAL DESCRIPTION INTRODUCTION In modern microprocessor/memory applications, address commands and control lines require system level termination to a voltage (VTT) equal to 1/2 the memory supply voltage (VDDQ). Having the termination voltage at midpoint, the power supply insures symmetry for switching times. Also, a reference voltage (VREF) that is free of any noise or voltage variations is needed for the DDR SDRAM input receiver, VREF is also equal to 1/2 VDDQ. Varying the VREF voltage will effect the setup and hold time of the memory. To comply with DDR requirements and to obtain best performance, VTT and VREF need to be tightly regulated to track 1/2 VDDQ across voltage, temperature, and noise margins. VTT should track any variations in the DC VREF value (VTT = VREF +/- 40 mV), (See Figure 4) for a DDR system level diagram. The 34716 supplies the VDDQ, VTT and a buffered VREF output. To ensure compliance with DDR specifications, the VDDQ line is applied to the VREFIN pin and divided by 2 internally through a precision resistor divider. This internal voltage is then used as the reference voltage for the VTT output. The same internal voltage is also buffered to give the VREF voltage at the VREFOUT pin for the application to use without the need for an external resistor divider. The 34716 provides the tight voltage regulation and power sequencing/ tracking required along with handling the DDR peak transient current requirements. It gives the user a complete DDR power supply solution with optimum performance. Buffering the VREF output helps its immunity against noise and load changes. The 34716 utilizes a voltage mode synchronous buck switching converter topology with integrated low RDS(ON) (50 m Ω) N-channel power MOSFETs to provide an output voltage with an accuracy of less than ±2.0 % output voltage. It has a programmable switching frequency that allows for flexibility and optimization over the operating conditions and can operate at up to 1.0 MHz to significantly reduce the external components size and cost. The 34716 can supply up to 5.0 A from one output and sink and source up to 3.0 A of continuous current from the other output. It provides protection against output overcurrent, overvoltage, undervoltage, and overtemperature conditions. It also protects the system from short circuit events. It incorporates a power good output signal to alert the host when a fault occurs. For boards that support the Suspend-To-RAM (S3) and the Suspend-To-Disk (S5) states, the 34716 offers the STBY and the SD pins respectively. Pulling any of these pins low, puts the IC in the corresponding state. By integrating the control/supervisory circuitry along with the Power MOSFET switches for the buck converter into a space-efficient package, the 34716 offers a complete, small- size, cost-effective, and simple solution to satisfy the needs of DDR memory applications. Besides DDR memory termination, the 34716 can be used to supply termination for other active buses and graphics card memory. It can be used in Netcom/Telecom applications like servers. It can also be used in desktop motherboards, game consoles, set top boxes, and high end high definition TVs. Figure 4. DDR System Level Diagram FUNCTIONAL PIN DESCRIPTION BOOTSTRAP INPUT (BOOT1, BOOT2) Bootstrap capacitor input pin. Connect a capacitor (as discussed in Bootstrap capacitor on page 20) between this pin and the SW pin of the respective channel to enhance the gate of the high-side Power MOSFET during switching. POWER INPUT VOLTAGE (PVIN1, PVIN2) Buck converter power input voltage. This is the drain of the buck converter high-side power MOSFET. SWITCHING NODE (SW1, SW2) Buck converter switching node. This pin is connected to the output inductor. POWER GROUND (PGND1, PGND2) Buck converter and discharge MOSFETs power ground. It is the source of the buck converter low-side power MOSFET. COMPENSATION INPUT (COMP1, COMP2) Buck converter external compensation network connects to this pin. Use a type III compensation network. VDDQ VDDQ VTT VREF BUS DDR Memory Controller DDR Memory Input Receiver RS RT |
Ähnliche Teilenummer - MC34716EP |
|
Ähnliche Beschreibung - MC34716EP |
|
|
Link URL |
Privatsphäre und Datenschutz |
ALLDATASHEETDE.COM |
War ALLDATASHEET hilfreich? [ DONATE ] |
Über Alldatasheet | Werbung | Kontakt | Privatsphäre und Datenschutz | Linktausch | Hersteller All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |