MIC5163_09 Datasheet, PDF(9/15 Page) Micrel Semiconductor – Dual Regulator Controller for DDR3 GDDR3/4/5 Memory Termination

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

MIC5163_09 Datasheet, PDF (9/15 Pages) Micrel Semiconductor – Dual Regulator Controller for DDR3 GDDR3/4/5 Memory Termination

◁

Micrel, Inc.

Functional Description

The MIC5163 is a high performance linear controller,

utilizing scalable N-Channel MOSFETs to provide

JEDEC compliant bus termination. Termination is

achieved by dividing down the VDDQ voltage by a half,

providing the reference (VREF) voltage. The MIC5163

controls two external N-Channel MOSFETs to form two

separate regulators. It operates by switching between

either the high-side MOSFET or the low-side MOSFET,

depending on whether the current is being sourced to

the load or being sinked by the regulator.

VDDQ

The VDDQ pin on the MIC5163 provides the source

current through the high side N-Channel and the

reference voltage to the device. The MIC5163 can

operate at VDDQ input voltages as low as 0.75V. A

bypass capacitance will increase performance by

improving the source impedance at higher frequencies.

VTT

VTT is the actual termination point. VTT is regulated to

VREF. Due to high speed signaling, the load current seen

by VTT is constantly changing. To maintain adequate

large signal transient response, Oscons and ceramics

are recommended on VTT. The Oscon capacitors provide

bulk charge storage while the smaller ceramic capacitors

provide current during the fast edges of the bus

transition.

MIC5163

VREF

Two resistors dividing down the VDDQ voltage provide

VREF. The resistors are valued at around 17kâ¦. A

minimum capacitor value of 120pF from VREF to ground

is mandatory.

VCC

VCC supplies the internal circuitry of the MIC5163 and

provides the drive voltage to enhance the external N-

Channel MOSFETs. A small 1Î¼F capacitor is

recommended for bypassing the VCC pin.

Feedback and Compensation

The feedback provides the path for the error amplifier to

regulate the VTT. An external resistor must be placed

between the feedback and VTT. Feedback resistor values

should not exceed 10kâ¦ and compensation capacitors

should not be less than 40pF.

Enable

The MIC5163 features an active high enable input. In the

off mode state, leakage currents are reduced to

microamperes. The enable input has thresholds

compatible with TTL/CMOS for simple logic interfacing.

The enable pin can be tied directly to VDDQ or VCC for

functionality.

April 2009

M9999-042209-A

▷