34704_11 Datasheet, PDF (5/54 Pages) Freescale Semiconductor, Inc – Multiple Channel DC-DC Power Management IC

PIN CONNECTIONS
Table 2. 34704 Pin Definitions (continued)
A functional description of each pin can be found in the Functional Pin Description section beginning on page 17.
Pin Number Device Pin Name Pin Function
Formal Name
Definition
11
A/B PVIN3
Power
REG3 power supply input This is the connection to the drain of the high side switch FET.
voltage
Input decoupling /filtering is required for proper REG3 operation.
Use a 10uf decoupling capacitor for better performance.
12
A/B
SW3
Output ^{REG3 switching node}
The inductor is connected between this pin and the regulated
REG3 output.
13
A/B VOUT3
Output
REG3 output voltage
This is the discharge path of REG3 output voltage.
return pin
14
A/B
FB3
Input
REG3 voltage feedback Connect the feedback resistor divider to this pin.
input for voltage
regulation/programming
15
A/B
SS
Input
Soft start time
The soft start time for all regulators can be adjusted by
connecting this pin to an external resistor divider between VDDI
and AGND pins.
16
A/B FREQ
Input
Oscillator frequency
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.
17
A/B
FB8
Input
REG8 voltage feedback Connect the feedback resistor divider to this pin.
input for voltage
regulation/programming
18
A/B
BT8
Passive ^{REG8 bootstrap capacitor Connect a 0.01 μF capacitor between this pin and SW8 pin to}
input pin
enhance the gate of the Synchronous Power MOSFET.
19
A/B VOUT8
Output
REG8 regulated output Connect this pin directly to the load directly and to the output
voltage pin
filter as close to the pin as possible.
20
21
22
23⁽¹⁾
A/B
SW8
A/B
SW1
A/B
VG
A
VOUT1
Output
Output
Passive
Output
REG8 switching node
REG1 switching node
REG1 regulated output
voltage before the cutoff
switch
REG1 regulated output
voltage pin.
The inductor is connected between this pin and the VIN pin.
The inductor is connected between this pin and the VIN Pin.
REG1 regulated output voltage before the cut-off switch. This
supplies the internal circuits and the gate drive
Connect this pin directly to the load directly and to the output
filter as close to the pin as possible.
B
NC0 No Connect -
Pin 23 is not connected.
24
A/B
BT1
Passive ^{REG1 bootstrap capacitor Connect a 1.0 μF capacitor between this pin and SW1 pin to}
input pin
enhance the gate of the Switch Power MOSFET.
25
A/B
SCL Input/Output I²C serial interface clock I²C serial interface clock input.
input
26
A/B
SDA _Input/Output I²C serial interface data I²C serial interface data input.
input
27
A/B
RST _{Open Drain} Power reset output signal This is an open drain output and must be pulled up by an
(Microprocessor Reset) external resistor to a supply voltage like V_IN.
28
A COMP7 Passive REG7 compensation
REG7 compensation network connection.
network connection
B
NC1 No Connect ^-
Pin 28 is not connected
29
A
VREF7
Output
REG7 resistor feedback Connect this pin to the bottom of the feedback resistor divider.
network reference voltage
B
NC2 _{No Connect} -
Pin 29 is not connected
Analog Integrated Circuit Device Data
Freescale Semiconductor
34704
5