IRU3138 Datasheet | International Rectifier

FEATURES 1A Peak Output Drive Capability 0.8V Precision Reference Voltage Available Shuts off both drivers at shorted output and shutdown 200KHz to 400KHz operation set by an external resistor ..Soft-Start Function Unmitted Error Amplifier available for DDR voltage tracking application Protects the output when control FET is shorted Synchronous Controller in 14-Pin Package DESCRIPTION The IRU3138 controller IC is designed to provide a low cost synchronous Buck regulator for voltage tracking applications such DDR memory and general purpose on-board DC to DC converter. Modern micro processors bined with DDR memory, need high-speed bandwidth data bus which requires a particular bus termination voltage. This voltage will be tightly regulated to track the half of chipset voltage for best performance. The IRU3138 together with two N-channel MOSFETs, provide a low cost solution for such applications. This device features a programmable frequency set from 200KHz to 400KHz, under-voltage lockout for both Vcc and Vc supplies, an external programmable soft-start function as well as output under-voltage detection that latches off the device when an output short is detected. APPLICATIONS DDR memory source sink Vtt application Graphic Card Low cost on-board DC to DC such as 5V to 3.3V, 2.5V or 1.8V TYPICAL APPLICATION 5V VDDQ (2.5V) C1 0.1u F 12V C2 1u F C3 2x 47u F L1 1u H C4 47u F DDR Memory R1 1K Vcc VREF VP Vc HDrv Q1 IRF7460 D1 BAT54 L2 3.3u H R2 1K SS/SD C5 0.1u F U1 IRU3138 LDrv PGnd Fb Vtt 1.25V @ 10A C6 2x 150u F 40m V Q2 IRF7456 Rt p C7 3300p F R3 13K Gnd Figure 1 - Typical application of IRU3138 when VTT tracks the VDDQ. PACKAGE ORDER INFORMATION TA (°C) 0 To 70 DEVICE IRU3138CS PACKAGE 14-Pin Plastic SOIC NB (S) Rev. 1.0 01/29/04 .irf. ABSOLUTE MAXIMUM RATINGS VCC Supply Voltage -0.5V - 25V VC Supply Voltage -0.5V - 25V Storage Temperature...