Setup and Operation
5
SLVUAQ5 – April 2016
Copyright © 2016, Texas Instruments Incorporated
TPS65320C-Q1-EVM User Guide
2.4
Operation
The input voltage range for the converter is 4 V to 40 V. Since the Buck configuration is for a 5 V output, a
higher voltage (approximately 6 V minimum) needs to be applied for normal performance. Also, the part
has an initial start-up-voltage of 6 V minimum, so even if the board is modified for lower-output voltages,
at first power-on, a supply-voltage of a minimum of 6 V needs to be applied once, before it can be
lowered.
For proper operation of the TPS65320C-Q1-EVM, properly configure BUCK_EN, LDO_EN, VIN_LDO, and
J6 using the jumper terminals as follows.
•
BUCK_EN – enabled (left)
•
LDO_EN – enabled (left)
•
JP4 - 2.0 MHz (R10)
•
VIN_LDO - installed
In this configuration, both regulators will turn on when power is applied. Disable regulators by moving the
enable jumpers to the right. If the BUCK is disabled, the LDO is supplied from VIN, consider the power-
dissipation at high VIN, VIN_LDO will be at GND-level in this condition. To change the switching
frequency, power-down the device before moving the jumper. To apply an external clock, install jumpers
to set the frequency to the set-point closest to the external clock. In case of a loss of the external clock,
the part falls back to the frequency created by the jumpers.
Configure the regulator using to the following settings in
Table 3. Regulator Configuration
REGULATOR
OUTPUT VOLTAGE
MAXIMUM OUTPUT CURRENT
BUCK
5 V
3.2 A
LDO
3.3 V
0.28 A
NOTE:
The output capacitors of the BUCK regulator are 25-V types, supporting up to 18 V of Vout.
In case of higher output voltage, the recommendation is to replace those with capacitors
providing higher-voltage ratings.
At low-switching frequencies, high load-transients and limited allowed deviation of Vout, larger
capacitance-values may be required. If needed, use the footprints of the unassembled electrolytic
capacitors C9 and C10. Low-ESR-capacitors will also further reduce the coupled noise from the buck to
the LDO.
On the EVM, a soft-start capacitor (C6) of 3.3 nF is installed, setting the time to approximately 1 ms. For
other soft-start times, the capacitor may be replaced.
3
Board Layout
,
, and
show the board layout for the TPS65320C-Q1-EVM. The EVM offers
resistors and jumpers to program the switching frequency. Jumpers are also provided to enable the
individual regulators.
The TPS65320C-Q1 converter offers high efficiency, but does dissipate power. The PowerPAD™ package
offers an exposed thermal pad to enhance thermal performance. This must be soldered to the copper
landing on the PCB, which is preferably connected to the GND-plane with multiple thermal vias for optimal
performance.
