PTV03020W_15 Datasheet, PDF (8/19 Pages) Texas Instruments – 18-A, 3.3-V INPUT NONISOLATED WIDE-OUTPUT ADJUST SIP MODULE

PTV03020W
SLTS243A – FEBRUARY 2005 – REVISED OCTOBER 2007
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Capacitor Vendor,
Type/Series (Style)
TDK, Ceramic X5R (SMD)
Table 1. Input/Output Capacitors (continued)
Working
Voltage
(V)
Value
(µF)
6.3
100
6.3
47
16
22
16
10
Capacitor Characteristics
Max ESR
at 100 kHz
(Ω)
Max Ripple
Current at
85°C (Irms)
(mA)
0.002
—
Physical Size
(mm)
3225
Quantity
Input
Bus
Optional
Output
Bus
Vendor
Part Number
≥1 ⁽³⁾
≥1 ⁽³⁾
≥1 ⁽³⁾
≥2 ⁽³⁾
≤3
C3225X5R0J107MT
≤5
C3225X5R0J476MT
≤5
C3225X5R1C226MT
≤5
C3225X5R1C106MT
Designing for Fast Load Transients
The transient response of the dc/dc converter has been characterized using a load transient with a di/dt of
1 A/µs. The typical voltage deviation for this load transient is given in the data sheet specification table using the
optional value of output capacitance. As the di/dt of a transient is increased, the response of a converter
regulation circuit ultimately depends on its output capacitor decoupling network. This is an inherent limitation with
any dc/dc converter once the speed of the transient exceeds its bandwidth capability. If the target application
specifies a higher di/dt or lower voltage deviation, the requirement can only be met with additional output
capacitor decoupling. In these cases special attention must be paid to the type, value, and ESR of the capacitors
selected.
If the transient performance requirements exceed that specified in the data sheet, or the total amount of load
capacitance is above 3000 µF, the selection of output capacitors becomes more important.
Adjusting the Output Voltage
The V_O Adjust control (pin 8) sets the output voltage of the PTV03020W product to a value over the range, 0.8 V
to 2.5 V. The adjustment method requires the addition of a single external resistor, R_SET, that must be connected
directly between the V_O Adjust and the regulator's output GND (pin 1 or 2). Without an adjust resistor, the output
voltage is set to its lowest value. Table 2 gives the preferred value of the external resistor for a number of
standard voltages, along with the actual output voltage that this resistance value provides. Figure 6 shows the
placement of the required resistor.
Table 2. Nearest Standard Values of R_SET for Common Output Voltages
V_O
(Required)
2.5 V ⁽¹⁾
R_SET
(Standard Value)
2.21 kΩ
V_O
(Actual)
2.502 V
2V
4.12 kΩ
2.010 V
1.8 V
5.49 kΩ
1.803 V
1.5 V
8.87 kΩ
1.504 V
1.2 V
17.4 kΩ
1.202 V
1V
36.5 kΩ
1.005 V
0.8 V
Open
0.800 V
(1) For V_O =2.5 V, the minimum input voltage is 3.15 V. See Electrical Characteristics for additional
information.
For other output voltages, the value of the required resistor can either be calculated or simply selected from the
range of values given in Table 3. Equation 1 may be used for calculating the adjust resistor value.
R_SET + 10 kW
0.8 V
V_O * 0.8
V
*
2.49
kW
(1)
8
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