33730_10 Datasheet, PDF (13/26 Pages) Freescale Semiconductor, Inc – Switch Mode Power Supply with Multiple Linear Regulators

FUNCTIONAL DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
MC33730 - Functional Block Diagram
Input Functions
Voltage Programmming Input
Protection FET Driver
Ignition Input
Internal Functions
Band Gap Reference
Sleep/Wake Circuitry
Output Functions
5 Volt Buck Switching
Regulator
5 Volt Protected Outputs
(VREF1, VREF2)
Linear Regulator Outputs
(VDDL, VDD3, VKAM)
Ignition Driver
Oscillator
Reset Circuitry
5.0 VOLT BUCK REGULATOR
This is the main regulator that supplies 5.0 Volts to the
following protected and regulated outputs, VREF1, VREF2,
VDD3, and VDDL.
OSCILLATOR
This is the frequency source for the switching (buck) 5 Volt
regulator. The frequency of oscillation is selected by an
external resistor to ground.
BAND GAP REFERENCE
This is the main voltage reference, which is used as the
standard for all the current and voltage sources in the
MC33730.
PROTECTION FET DRIVER
The protection FET is used to prevent reverse battery
connections from damaging the MC33730. The gate drive for
the Protection FET is provided by this driver circuit.
SLEEP/WAKE CIRCUITRY
This circuitry is responsible for the two main modes of
operation for the MC33730, Sleep mode and Wake mode. In
the Sleep mode, only the keep alive outputs are active, and
the rest of the circuitry is in a low power drawing sleep state.
In the Wake mode, the MC33730 is fully functional and
normal current is being consumed.
IGNITION DRIVER
This block of circuitry controls all the voltage outputs,
except for the keep alive voltage output(s). It also provides an
output signal to indicate that the ignition switch has been
activated.
VREF1
This output is one of two protected 5.0 volt outputs that can
be used to supply external sensors or other analog circuits
requiring a regulated, short-circuit protected 5.0 volt supply.
VREF2
This output is one of two protected 5.0 volt outputs that can
be used to supply external sensors or other analog circuits
requiring a regulated, short-circuit protected 5.0 volt supply.
VDD3 REGULATOR
This is one of three, voltage programmable, regulated
supplies. This supply is controlled by the ignition switch.
VDDL REGULATOR
This is one of three, voltage programmable, regulated
supplies. This supply is controlled by the ignition switch.
VKAM
This is one of three, voltage programmable, regulated
supplies. This supply is NOT controlled by the ignition switch.
VOLTAGE PROGRAMMING
P1, P2, and P3 are three logic level inputs that control the
voltage that is available on the VDD3, VDDL and VKAM
outputs.
Table 6 indicates the 8 different combinations of P1, P2,
and P3 and the resultant voltage values.
Analog Integrated Circuit Device Data
Freescale Semiconductor
33730
13