Datasheet

Modifications
1-4
1.3 Modifications
Whereas the TPS54010EVM−067 is designed to demonstrate the small size
that can be attained when designing with the TPS54010, many of the features,
which allow for extensive modifications, have been included in this EVM.
1.3.1 Output Voltage Set Point
To change the output voltage of the EVM, it is necessary to change the value
of resistor R2. Changing the value of R2 can change the output voltage in the
range of 0.9 V to 2.5 V. The value of R2 for a specific output voltage can be
calculated by using Equation 1−1.
Equation 1−1.
R
2
+ 10 kW
0.891 V
V
O
* 0.891 V
Table 1−3 lists the R2 values for some common output voltages. Note that
PVIN must be greater than 3 V to generate a 2.5-V output.
Table 1−3.Output Voltages Available
Output Voltage (V) R2 Value (W)
1.2 28.5 k
1.5 14.7 k
1.8 9.76 k
2.5 5.49 k
The minimum output voltage is limited by the minimum controllable on time of
the device, 200 ns, and depends on the duty cycle and operating frequency.
The approximate minimum output voltage can be calculated using
Equation 1−2.
Equation 1−2.
V
OUTMIN
+ 200 nsec ƒ
s
V
INMAX
1.3.2 Switching Frequency
The switching frequency of the EVM is set to 700 kHz by setting R4 to 71.5 kΩ.
The switching frequency can be trimmed to any value between 250 kHz and
700 kHz by changing the value of R4 using Equation 1−1. The EVM also can
be set to one of the two internally programmed frequencies. Remove R4 and
use a jumper on the J4 pin 3 header to select 350−kHz or 550−kHz operation.
The jumper settings are conveniently silk-screened on the EVM printed-circuit
board. Note that decreasing the switching frequency results in increased
output ripple unless the value of L1 is increased.
Equation 1−3.
ƒ
SW
+
100 kW
R
4
500(kHz)