MP20073 MPS, MP20073 Datasheet - Page 7

• Manufacturer Part Number: MP20073
• Description: 2a, 1.3v?6.0v Ddr Memory Termination Regulator
• Manufacturer: MPS

DETAILED OPERATING DESCRIPTION
Control Logic
The internal control logic is powered by VDRV.
The IC is enabled whenever VDDQ UVLO is
pulled low. VTTREF output begins to track
VREF/2. When the VTTEN pin is high, the VTT
regulator is activated.
VTTREF Output
The VTTREF output tracks VREF/2 with ±2%
accuracy. It has source current capability of up to
15mA. VTTREF should be bypassed to analog
ground of the device by 1.0µF ceramic capacitor
for stable operation.
The VTTREF is turned on as long as VDDQ is
higher the UVLO threshold. VTTREF features a
soft-start and tracks VREF/2.
Output Voltages Sensing
The VTT output voltage is sensed across the
VTTSEN and GND pins. The VTTSEN should be
connected to the VTT regulation point, which is
MP20073 Rev. 0.9
10/22/2010
VREF
3.3V
GND
VEN
EN
REF
MP20073 – 2A, 1.3V-6.0V INPUT, DDR MEMORY TERMINATION REGUALTOR
VDRV
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
DDQ
UVLO
DDQ
Figure 1—Functional Block Diagram
© 2010 MPS. All Rights Reserved.
Soft-Start
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& Deadband
Regulation
Control
VTT
usually the VTT local bypass capacitor, via a
direct
connected via a direct sense trace to the ground
of the VTT local bypass capacitor for load.
VDDQ UVLO Protection
For
protection, the MP20073 monitors VDDQ voltage.
When the VDDQ voltage is lower than UVLO
threshold voltage, the VTT regulator is shut off.
Current Protection of VTT Active Terminator
To provide protection for the internal FETs, over
current limit(OCL) of 3A is implemented.
The LDO has a constant overcurrent limit (OCL)
at 3A. This trip point is reduced to 1.0 A if the
output voltage drops below 1/3 of the target
voltage.
VDDQ
sense
undervoltage
trace.
Current
Current
Limiter
Limiter
The
VTT
VTTSEN
VTTREF
DDQ
GND
lockout
VDDQ
VTT
VTTSEN
VTTREF
should
(UVLO)
be
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