34704_11 Datasheet, PDF (17/54 Pages) Freescale Semiconductor, Inc – Multiple Channel DC-DC Power Management IC

FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
REG5 BOOST STAGE BOOTSTRAP CAPACITOR
INPUT PIN (BT5U)
Connect a 1.0 μF capacitor between this pin and SW5U
pin to enhance the gate of the Switch Power MOSFET.
REG4 BUCK STAGE BOOTSTRAP CAPACITOR
INPUT PIN (BT4D)
Connect a 0.01 μF capacitor between this pin and SW4D
pin to enhance the gate of the Switch Power MOSFET.
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.
REG4 BUCK STAGE SWITCHING NODE (SW4D)
The inductor is connected between this pin and the SW4U
pin.
REG4 REGULATED OUTPUT VOLTAGE PIN
(VOUT4)
Connect this pin to the load and to the output filter as close
to the pin as possible.
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)
Connect a 0.01 μF capacitor between this pin and SW4U
pin to enhance the gate of the Switch Power MOSFET.
REG4 VOLTAGE FEEDBACK INPUT FOR
VOLTAGE REGULATION/PROGRAMMING (FB4)
Connect the feedback resistor divider to this pin.
REG4 COMPENSATION NETWORK CONNECTION
(COMP4)
REG4 compensation network connection.
REG3 BOOTSTRAP CAPACITOR INPUT PIN (BT3)
Connect a 0.01 μF capacitor between this pin and SW3 pin
to enhance the gate of the Switch Power MOSFET.
REG3 POWER SUPPLY INPUT VOLTAGE (PVIN3)
This is the connection to the drain of the high side switch
FET. Input decoupling /filtering is required for proper REG3
operation.
REG3 SWITCHING NODE (SW3)
The inductor is connected between this pin and the
regulated REG3 output.
REG3 OUTPUT VOLTAGE RETURN PIN (VOUT3)
This is the discharge path of REG3 output voltage.
REG3 VOLTAGE FEEDBACK INPUT FOR
VOLTAGE REGULATION/PROGRAMMING (FB3)
Connect the feedback resistor divider to this pin.
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.
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 F_SW1 value.
REG8 VOLTAGE FEEDBACK INPUT FOR
VOLTAGE REGULATION/PROGRAMMING (FB8)
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 I_SET
resistor to GND to force the operating current. Refer to
Figure 10 and Figure 11. Exclude the components not used.
REG8 BOOTSTRAP CAPACITOR INPUT PIN (BT8)
Connect a 0.01 μF capacitor between this pin and SW8 pin
to enhance the gate of the Synchronous Power MOSFET.
REG8 REGULATED OUTPUT VOLTAGE PIN
(VOUT8)
Connect this pin directly to the load directly and to the
output filter as close to the pin as possible.
REG8 SWITCHING NODE (SW8)
The inductor is connected between this pin and VIN pin.
REG1 SWITCHING NODE (SW1)
The inductor is connected between this pin and VIN pin.
REG1 REGULATED OUTPUT VOLTAGE BEFORE
THE CUT-OFF SWITCH (VG)
REG1 regulated output voltage before the cutoff switch.
This supplies the internal circuits and the gate drive.
Analog Integrated Circuit Device Data
Freescale Semiconductor
34704
17