www.ti.com
3
Schematic
Notes
R6 =26.7k for 3.3 Vout, R6 = 16.2k for 5.0 Vout
+
+
D3 : Do not populate. SOT 23 Common Cathode Dual Schottky
3.1
Adjusting Output Voltage (R6 and R10)
V
vout
V
ref
1
R
10
R
6
(1)
3.2
Using Remote Synchronizing (TP6)
Schematic
NOTE: For reference only; see Table 2, Bill of Materials for specific values
Figure 1. TPS40200EVM-001 Schematic
The regulated output voltage can be adjusted within a limited range by changing the ground resistor in the
feedback resistor divider (R6 and R10). The output voltage is given by
Equation 1
.
Where V
REF
= 0.700 V and R10 = 100 k
Ω
Table 1
contains common values for R6 to generate popular output voltages. TPS40200EVM-001 is stable
through these output voltages with the efficiency rising with output voltage.
Table 1. Adjusting V
OUT
With R6 Rounded to
Standard 1% Resistor Values
V
OUT
- Output Voltage (V)
R6 - Feedback Resistor Divider
(k
Ω
)
5
16.2
3.3
26.7
2.5
39
2
53.6
1.8
63.4
1.5
86.6
1.2
140
The TPS40200EVM-001 board has a synchronizing circuit that uses TP6 as an input. A logic high at this
input turns on a small signal FET (Q1) whose drain is connected to the oscillator setting node (RC) on the
TPS40200. The switching of this transistor over-drives the ramp associated with the internal oscillator and
causes the PWM switching to follow the input clock frequency. For reliable operation, the external clock
SLVU147A – February 2006 – Revised March 2006
Using the TPS40200
3
Submit Documentation Feedback
