Datasheet

TPS2359

www.ti.com

SLUS792H –FEBRUARY 2008–REVISED MAY 2013

APPLICATION INFORMATION

Introduction

The TPS2359 controls two 12-V power paths and two 3.3-V power paths. Each power path can draw from a

single common supply, or from two independent supplies. The TPS2359 occupies a 36-pin QFN package. An I

interface not only enables the implementation of two AdvancedMC™ slots using one small integrated circuit, but

it also provides many opportunities for design customization. The following sections describe the main functions

of the TPS2359 and provide guidance for designing systems around this device.

Control Logic and Power-On Reset

The TPS2359's circuitry, including the I

C interface, draws power from an internal bus fed by a preregulator. A

capacitor attached to the VINT pin provides decoupling and output filtering for this preregulator. It can draw

power from any of four inputs (IN12A, IN12B, IN3A, or IN3B) or from any of four outputs (OUT12A, OUT12B,

OUT3A, or OUT3B). This feature allows the internal circuitry to function regardless of which channels receive

power, or from what source. The four external FET drive pins (PASSA, PASSB, BLKA, and BLKB) are held low

during startup to ensure that the two 12-V channels remain off. The internal 3.3-V channels are also held off.

When the voltage on the internal VINT rail exceeds approximately 1 V, the power-on reset circuit loads the

internal registers with the default values listed in Detailed Description of Registers section.

Enable Functions

Table 13 lists the specific conditions required to enable each of the four channels of the TPS2359. The 3.3-V

channels each have an active-high enable pin with a 200-kΩ internal pullup resistor. The enable pin must be

pulled high, or allowed to float high, in order to enable the channel. The I

C interface includes an enable bit for

each of the four channels. The bit corresponding to a channel must be set in order to enable it. All four channels

also include bleed down threshold comparators. Setting the bleed down control bit ensures that a channel cannot

turn on until its output voltage drops below about 100 mV. This feature supports applications in which removal

and restoration of power re-initializes the state of downstream loads. The 12-V channels also include a cross-

connection feature to support PICMG.AMC™ and MicroTCA™ requirements. When enabled, this feature ensures

that when a 3.3-V output drops below 2.85 V the associated 12-V channel will automatically shut off. This feature

can be disabled by setting the DCC bit in Register 6.

Table 13. Enable Requirements

Channel Enable pins Enable bits Bleed down Cross connection

3A EN3A > 1.4 V 3AEN = 1 OUT3A < 0.1 V or 3AUV = 0

3B EN3B > 1.4 V 3BEN = 1 OUT3B < 0.1 V or 3BUV = 0

12A 12AEN = 1 OUT12A < 0.1 V or 12AUV = 0 3APG = 0 or DCC = 1

12B 12BEN = 1 OUT12B < 0.1 V or 12BUV = 0 3BPG = 0 or DCC = 1

Product Folder Links: TPS2359