Application Brief
Linear Products
DCĆtoĆDC Converter Parallel Operation Using
Droop Compensation of TPS5210
When a power supply is designed to produce a high output current, a distributed structure of power supplies is sometimes
preferred over a single bulky power converter. Figure 1 shows the application circuit of the TPS5210 in parallel operation.
To operate the paralleled-circuitry, the voltage reference (Vref) of each module should be set to the same value with the
voltage identification code (VID).
The TPS5210 has a droop-compensation feature, which can be easily implemented for parallel operation of dc-to-dc
converters without any additional circuitry. The TPS5210 senses the load current using the internal on-resistance between
the drain and source of the MOSFET such that the output voltage falls slightly as the load current increases (droop
compensation). When one of the modules drives a higher output current (see Figure 1), the TPS5210 of that module
produces a proportionally decreased output voltage, and the output voltages of the other modules increase. This results
in balanced load sharing.
On-resistance current sensing will work when precision load sharing is not required. In order to obtain higher-accuracy
load sharing, a precision resistor is inserted in series with the upper-side MOSFET as shown in Figure 2. The application
circuit of each module is identical to Figure 18 in the TPS5210 data sheet (SLVS171), except for the extra resistor that
is used for current sensing. A resistance value of 0.01 Ω with tight tolerance is recommended for this application.
Usually n+1 modules are recommended for parallel operation of dc-to-dc converters, where n is the minimum number
of modules required to deliver the load power. This redundancy is desirable for high-reliability applications.
Input
12 V
DC/DC Converter
Using
TPS5210
DC/DC Converter
Using
TPS5210
DC/DC Converter
Using
TPS5210
Output
Io1
Output
Io2
Io
Load
Output
Ion+1
Figure 1. Application Circuit of TPS5210 in Parallel Operation
SLVA060
Application Brief
Standard Method of
Sensing Load Current
TPS5210
HISENSE
IOUTLO
Input
12 V
HIGHDR
+
LOSENSE
TPS5210
12 V
VCC
IOUTLO
R1
3.3 kΩ
0.033 µf
LOWDR
0.01 Ω
LOSENSE
IOUT
Output
Q3-Q5
LOWDR
DROOP
R2
1 kΩ
Q1-Q2
HIGHDR
HISENSE
+
150 Ω
DRVGND
VSENSE
10 kΩ
1000 pF
Precision Method of
Sensing Load Current
Figure 2. DC-to-DC Converter Using the TPS5210
Printed in U.S.A.
SLVA060