TC1267_13 Datasheet, PDF (1/14 Pages) Microchip Technology – 400mA PCI LDO

TC1267
400mA PCI LDO
Features
• Glitch Free Transition Between Input Sources
• Automatic Input Source Selection
• External PMOS Bypass Switch Control
• Built-in 5V Detector
• 1% Regulated Output Voltage Accuracy
• 400mA Load Current Capability
• Kelvin Sense Input
• Low Ground Current, Independent of Load
Applications
• PCMCIA
• PCI
• Network Interface Cards (NICs)
• Cardbus^TM Technology
• Desktop Computers
Device Selection Table
Part Number
TC1267VET
Package
5-Pin DDPAK
Junction
Temp. Range
-5°C to +95°C
Pin Configuration
5-Pin DDPAK
Tab is GND
TC1267
1 234 5
General Description
The TC1267 is an application-specific, low dropout
regulator (LDO), specifically intended for use in PCI
peripheral card applications complying with PCI Power
Management (PCI 2.0). It provides an uninterrupted,
3.3V output voltage when the main (5V) or auxiliary
(3.3V) input voltage supplies are present.
The TC1267 consists of an LDO, a voltage threshold
detector, external switchover logic and gate drive
circuitry. It functions as a conventional LDO as long as
the voltage on the main supply input (V_IN) is above the
lower threshold (3.90V typical). Should the voltage on
V_IN fall below the lower threshold, the LDO is disabled
and an external P-channel MOSFET is automatically
turned on, connecting the auxiliary supply input to
V_OUT, and ensuring an uninterrupted 3.3V output. The
main supply is automatically selected, if both the main
and auxiliary input supplies are present, and transition
from one input supply to the other is ensured glitch-
free. High integration, automatic secondary supply swi-
tchover, Kelvin sensing, and small size make the
TC1267 the optimum LDO for PCI 2.0 applications.
Functional Block Diagram
V_IN
V_AUX
Detect
Bandgap
Reference
GND
–
E/A
+
D_R
V_OUT
 2001-2012 Microchip Technology Inc.
DS21378C-page 1