KIT33730EKEVBE Evaluation Board
, Rev. 1.0
6
Freescale Semiconductor
Using Hardware
4.2.2
VDD3 Jumper
In the state where VDD3 is desired to be in standby, the VDD3 jumper is used to short the Base of the
VDD3 transistor to ground. The default case (
Normal
) is to leave the base connected to VDD3_B.
Jumper should be connected to Normal except for the cases where P1, P2, and P3 are as follows:
4.2.3
Slew Rate (SR) Jumper
The Slew Rate Control Jumper Allows For Configurable Slew Rates For The Switching Regulator.
Connected To Boot The Slow Slew Rate Is Active And Connected To Sw The Fast Slew Rate Is Selected.
The Pin Can Be Left Open Which Results In The Medium Slew Rate Control.
Setup Pins
The 33730 has multiple pins used to do initial setup for the IC. When the IC is powered up a series of
checks are done to determine the P1, P2, P3, HRT, SR and FREQ state.
The P1, P2, and P3 states are connected to jumpers to allow the user to configure the supply rails easily.
Once the IC has determined their state at startup, the status is latched into registers and changing the
jumpers does not affect the operation until the next POR or start up occurs.
The HRT pin is set to 10k. The resistor connected to HRT is R1.
The SR state is determined by the SR jumper. The slew rate of the switching regulator can be selected
to range from slow, medium and fast depending on the location (or open) of the jumper.
The FREQ pin is connected to ground via a 10kohm resistor. This pin resistance to ground determines
the frequency operation of the switching regulator. The resistor connected to FREQ is R9.
Output Supply Pins
There are multiple output power supplies integrated into the integrated circuit.
The main switching regulator, VDDH, uses a fixed frequency PWM voltage mode control. It has a 3.5A
current limit (typical) and the slew-rate is adjustable via a control pin to reduce switching noise. The
switching regulator has an adjustable frequency oscillator, which allows the user to optimize its operation
over a wide range of input voltages and component values. The VDDH regulator supplies a 5v rail and is
used as the internal power supply for VREF1 and VREF2 along with the external rail for VDD3 and VDDL.
Associated with the VDDH regulator is the INV and VCOMP pins which have been connected to optimize
the compensation for the step down regulator. A bootstrap capacitor is connected from the VSW pin to
the BOOT pin.
The linear regulators can be configured either as two normal mode regulators (VDD3, VDDL) and one
standby regulator (VKAM), or as one normal mode linear regulator (VDDL) and two standby regulators
(VKAM and VDD3 Standby). Two protected outputs, VREF1 and VREF2, are used to provide power to
external sensors.
P1
P2
P3
VDD3
Low
High
High
3.3V Standby
Low
Low
High
2.6V Standby
Low
Low
Low
2.6V Standby
SR
CONDITION FOR SLEW RATE
Boot
Slow Slew rate
Open
Medium Slew rate
SW
Fast Slew rate
