FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
REG5 BOOST STAGE BOOTSTRAP CAPACITOR REG3 SWITCHING NODE (SW3)
INPUT PIN (BT5U)
The inductor is connected between this pin and the
regulated REG3 output.
Connect a 1μF capacitor between this pin and SW5U pin
to enhance the gate of the Switch Power MOSFET.
REG3 OUTPUT VOLTAGE RETURN PIN (VOUT3)
REG4 BUCK STAGE BOOTSTRAP CAPACITOR
INPUT PIN (BT4D)
This is the discharge path of REG3 output voltage.
REG3 VOLTAGE FEEDBACK INPUT FOR
VOLTAGE REGULATION/PROGRAMMING (FB3)
Connect a 0.01μF capacitor between this pin and SW4D
pin to enhance the gate of the Switch Power MOSFET.
Connect the feedback resistor divider to this pin.
REG4 POWER SUPPLY INPUT VOLTAGE (PVIN4)
This is the connection to the drain of the high side switch
FET. Input decoupling /filtering is required for proper REG4
operation.
SOFT START TIME (SS)
The soft start time for all regulators can be adjusted by
connecting this pin to an external resistor divider between
VDDI and AGND pins.
REG4 BUCK STAGE SWITCHING NODE (SW4D)
The inductor is connected between this pin and the SW4U
pin.
OSCILLATOR FREQUENCY (FREQ)
The oscillator frequency can be adjusted by connecting
this pin to an external resistor divider between VDDI and
AGND pins. This pin sets FSW1 value.
REG4 REGULATED OUTPUT VOLTAGE PIN
(VOUT4)
REG8 VOLTAGE FEEDBACK INPUT FOR
VOLTAGE REGULATION/PROGRAMMING (FB8)
Connect this pin to the load and to the output filter as close
to the pin as possible.
Connect the feedback resistor divider to this pin, when
voltage mode control is used. When current mode control is
used, connect this pin between the LED string and an ISET
resistor to GND to force the operating current. Refer to
Figure 7 and Figure 8. Exclude the components not used.
REG4 BOOST STAGE SWITCHING NODE (SW4U)
The inductor is connected between this pin and the SW4D
pin.
REG4 BOOST STAGE BOOTSTRAP CAPACITOR
INPUT PIN (BT4U)
REG8 BOOTSTRAP CAPACITOR INPUT PIN (BT8)
Connect a 0.01μF capacitor between this pin and SW8 pin
to enhance the gate of the Synchronous Power MOSFET.
Connect a 0.01μF capacitor between this pin and SW4U
pin to enhance the gate of the Switch Power MOSFET.
REG8 REGULATED OUTPUT VOLTAGE PIN
(VOUT8)
REG4 VOLTAGE FEEDBACK INPUT FOR
VOLTAGE REGULATION/PROGRAMMING (FB4)
Connect this pin directly to the load directly and to the
output filter as close to the pin as possible.
Connect the feedback resistor divider to this pin.
REG4 COMPENSATION NETWORK CONNECTION
(COMP4)
REG8 SWITCHING NODE (SW8)
The inductor is connected between this pin and VIN pin.
REG4 compensation network connection.
REG1 SWITCHING NODE (SW1)
REG3 BOOTSTRAP CAPACITOR INPUT PIN (BT3)
The inductor is connected between this pin and VIN pin.
Connect a 0.01μF capacitor between this pin and SW3 pin
to enhance the gate of the Switch Power MOSFET.
REG1 REGULATED OUTPUT VOLTAGE BEFORE
THE CUT-OFF SWITCH (VG)
REG3 POWER SUPPLY INPUT VOLTAGE (PVIN3)
REG1 regulated output voltage before the cutoff switch.
This supplies the internal circuits and the gate drive.
This is the connection to the drain of the high side switch
FET. Input decoupling /filtering is required for proper REG3
operation.
34704
Analog Integrated Circuit Device Data
Freescale Semiconductor
17
FREESCALE [ Freescale ]
