Analog Integrated Circuit Device Data

Freescale Semiconductor

11

34713

FUNCTIONAL DESCRIPTION

FUNCTIONAL INTERNAL BLOCK DESCRIPTION

threshold, this block will alert the system control for

further commands.

• Output Overvoltage and Undervoltage Monitoring: This

block monitors the buck converter output voltage to

ensure it is within regulation boundaries. If not, this

block alerts the system control for further commands.

CONTROL AND SUPERVISORY FUNCTIONS

This block is used to interface with an outside host. It

contains the following circuits:

• Shutdown Control Input: An outside host can put the

34713 device into shutdown mode by sending a logic

“0” to the SD pin.

• Power Good Output Signal PG: The 34713 can

communicate to an external host that a fault has

occurred by releasing the drive on the PG pin high,

allowing the signal/pin to be pulled high by the external

pull-up resistor.

TRACKING AND SEQUENCING

This block allows the output of the 34713 to track the

voltage applied at the VREFIN pin in different tracking

configurations. This will be discussed in further details later in

this document. For power down during a shutdown mode, the

34713 uses internal discharge MOSFET (Figure 2) to

discharge the output. The discharge MOSFET is only active

during shutdown mode. Using this block along with

controlling the SD pin can offer the user power sequencing

capabilities by controlling when to turn the 34713 output on or

off.

BUCK CONVERTER

This block provides the main function of the 34713: DC to

DC conversion from an un-regulated input voltage to a

regulated output voltage used by the loads for reliable

operation. The buck converter is a high performance, fixed

frequency (externally adjustable), synchronous buck PWM

power MOSFETs saving board space and enhancing

efficiency. The switching regulator output voltage is

adjustable with an accuracy of less than ±2 % to meet today’s

requirements. Its output has the ability to track the voltage

applied at the VREFIN pin. The regulator's voltage control

loop is compensated using a type III compensation network,

with external components to allow for optimizing the loop

compensation, for a wide range of operating conditions. A

typical Bootstrap circuit with an internal PMOS switch is used

to provide the voltage necessary to properly enhance the

high-side MOSFET gate.

The 34713 has the ability to supply up to 5.0 A of

continuous current, making it suitable for many high current

applications.