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PRODUCT SPECIFICATION
RC5031
3
P
Pin Assignments
Pin Descriptions
Pin
Name
NC
VREF
Pin
Number
1
2
Pin Function Description
No connection.
Voltage reference test point.
This pin provides access to the internal precision 1.5V
bandgap reference and should be decoupled to ground using a 0.1
m
F ceramic capacitor.
No load should be connected to this pin.
High side current feedback for switching regulator.
Pins 3 and 4 are used as the inputs
for the current feedback control loop and as the short circuit current sense points. Careful
layout of the traces from these pins to the current sense resistor is critical for optimal
performance of the short circuit protection scheme. See Applications Information for details.
Low side current feedback for switching regulator.
See Applications Information for
details.
Voltage feedback for switching regulator.
This input is active when a logic level LOW is
input on pin 16 (SWCTRL). Using two external resistors, it sets the output voltage level for
the switching regulator. See Applications Information for details.
Switching Regulator V
cc
.
Power supply for switching regulator control circuitry and
voltage reference. Connect to system 5V supply and decouple to ground with 0.1
m
F
ceramic capacitor.
No connection.
Power Ground.
Return pin for high currents flowing in pins 9, 10 and 12 (SDRV, VCCP and
LDRV). Connect to a low impedance ground. See Application Information for details.
FET driver output for switching regulator.
Connect this pin to the gate of the N-channel
MOSFET M1 as shown in Figure 11. The trace from this pin to the MOSFET gate should be
kept as short as possible (less than 0.5"). See Applications Information for details.
Switching regulator gate drive V
cc
.
Power supply for SDRV output driver. Connect to
system 12V supply with R-C filter shown in Figure 11. See Applications Information for
details.
No connection.
Analog ground.
All low power internal circuitry returns to this pin. This pin should be
connected to system ground so that ground loops are avoided. See Applications
Information for details.
External capacitor.
A 180pF capacitor is connected to this pin as part of the constant
on-time pulse width circuit. Careful layout of this pin is critical to system performance.
See Applications Information for details.
Switching regulator control input.
Accepts TTL/open collector input levels. A logic level
HIGH on this pin presets the switching regulator output voltage at 3.5V using internal
resistors. A logic level LOW on this pin will select the output voltage set by two external
resistors and the voltage feedback control pin 5 (VFBSW). See Applications Information for
details.
IFBH
3
IFBL
4
FBSW
5
VCCA
6
NC
7
8
GNDP
SDRV
9
VCCP
10
NC
GNDA
11–13
14
CEXT
15
SWCTRL
16
NC
VREF
IFBH
IFBL
FBSW
VCCA
NC
SWCTRL
CEXT
GNDA
NC
NC
NC
VCCP
1
2
3
4
5
6
7
16
65-5031-02
15
14
13
12
11
10
GNDP
SDRV
8
9