Datasheet

3.1 ADJUSTING OUTPUT VOLTAGE (R1)
The regulated output voltage can be adjusted within a limited range by changing the ground resistor in the
feedback resistor divider (R1). The output voltage is given by the formula
1
15
R
RR
VREFVOUT
VV
+
×
=
Where V
VREF
= 0.591V and R5 = 10KΩ
Table 2 contains common values for R1 to generate popular output voltages. TPS40190EVM-001 is stable
through these output voltages but the efficiency may suffer as the power stage is optimized for the 1.5V output.
V
OUT
R1
3.3V
1
2.15K
2.5V
1
3.09K
2.25V 3.57K
2.0V 4.22K
1.8V 4.87K
1.5V 6.49K
1.2V 9.76K
Table 2: Adjusting V
OUT
with R1
3.2 ADJUSTING SHORT CIRCUIT PROTECTION (R6)
The TPS40190 uses a selectable current limit for short circuit protection. The current limit is selected from 3
levels by placing a resistor at R6. The TPS40190 compares the voltage drop across the high-side FET (VDD to
SW) to an internal reference voltage selected during start-up. The voltage levels are shown in Table 3.
V
SCP
R6
160mV 3.9 K
320mV OPEN
420mV 12 K
Table 3: Adjusting V
SCP
with R6
The current before declaring short circuit protection can be determined by dividing the V
SCP
by the R
DS(ON)
of the
High-Side FET (Q2)
3.3 DISABLE (TP1 & SW1)
TPS40190EVM-001 provides both a Disable input (TP1) and a Disable switch (SW1) to allow the user to evaluate
the TPS40190’s Enable Function. When the switch is ON or TP1 is pulled high, Q1 pulls EN (U1 Pin 1) to ground
and disables the TPS40190 IC.
1
For Output Voltages greater than 2.5V, Change C11 to 330μF 4V or higher PosCAP