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.
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
voltage-mode control. It drives integrated 45 mΩ N-channel
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.
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
The 34713 has the ability to supply up to 5.0 A of
continuous current, making it suitable for many high current
applications.
34713
Analog Integrated Circuit Device Data
Freescale Semiconductor
11
FREESCALE [ Freescale ]
