MIC5164 Datasheet, PDF (8/23 Pages) Micrel Semiconductor – Dual Regulator Controller for DDR3 GDDR3/4/5 Memory and High-Speed Bus Termination

Micrel, Inc.
Functional Description
The MIC5164 is a high-performance linear controller,
utilizing scalable N-Channel MOSFETs to provide
JEDEC-compliant bus termination. Termination is
achieved by dividing down the V_DDQ voltage half,
providing the reference (V_REF) voltage. The MIC5164
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 sunk by the regulator.
VDDQ
The VDDQ pin on the MIC5164 provides the source
current through the high side N-Channel and the
reference voltage to the device. The MIC5164 can
operate at V_DDQ input voltages as low as 1.35V. A
bypass capacitance will increase performance by
improving the source impedance at higher frequencies.
VREF
Two resistors divide down the V_DDQ voltage to provide
V_REF. The resistors are valued at around 21kΩ. A
minimum capacitor value of 120pF from V_REF to ground
is mandatory.
MIC5164
VCC
VCC supplies the internal circuitry of the MIC5164 and
provides the voltage to drive the external N-Channel
MOSFETs. A small 1μF ceramic capacitor is
recommended for bypassing the VCC pin.
FB and COMP
The feedback (FB) pin provides the path for the error
amplifier to regulate V_TT. A feedback resistor is
recommended and resistor values should not exceed
10kΩ. The compensation capacitors should not be less
than 40pF.
EN
The MIC5164 features an active-high enable (EN) input.
In the off-mode state, leakage currents are reduced to
microamperes. EN has thresholds compatible with
TTL/CMOS for simple logic interfacing.
PG
MIC5164 features a Power Good (PG) output. PG is an
open-drain output with an active-high signal. PG requires
a pull-up resistor to VCC.
June 2010
8
M9999-061510