TPS63000
TPS63001
TPS63002
www.ti.com
SLVS520–MARCH 2006
APPLICATION INFORMATION
DESIGN PROCEDURE
The TPS6300x dc/dc converters are intended for systems powered by one-cell Li-Ion or Li-Polymer with a typical
voltage between 2.3 V and 4.5 V. They can also be used in systems powered by a double or triple cell Alkaline,
NiCd, NiMH battery with a typical terminal voltage between 1.8 V and 5.5 V . Additionally, any other voltage
source with a typical output voltage between 1.8 V and 5.5 V can power systems where the TPS6300x is used.
Programming the Output Voltage
Within the TPS6300X family there are fixed and adjustable output voltages available. To properly configure the
fixed output voltage devices the FB pin is used to sense the output voltage. This means that it must be
connected directly to VOUT. At the adjustable output voltage versions and external resistor divider is used to
adjust the output voltage. The resistor divider must be connected between VOUT, FB and GND. When the output
voltage is regulated properly the typical value of the voltage at the FB pin is 500 mV. The maximum
recommended value for the output voltage is 5.5 V. The current through the resistive divider should be about 100
times greater than the current into the FB pin. The typical current into the FB pin is 0.01 µA, and the voltage
across the resistor between FB and GND, R2, is typically 500 mV. Based on those two values, the recommended
value for R2 should be lower than 500 kΩ, in order to set the divider current at 1 µA or higher. It is recommended
to keep the value for this resistor in the range of 200 kΩ. From that, the value of the resistor connected between
VOUT and FB, R1, depending on the needed output voltage (VO), can be calculated using Equation 1:
V
OUT
ǒ Ǔ
R ń R
) 1
1
2
V
FB
(1)
If as an example, an output voltage of 3.3 V is needed, a 1.0 MΩ resistor should be chosen for R1. To improve
control performance using a feedforward capacitor in parallel to R1 is recommended. The value for the
feedforward capacitor can be calculated using Equation 2.
10 qs
C
ff
R
1
(2)
L1
4.7 mF
L1
L2
V
OUT
V
IN
VIN
VOUT
1.8 V to
5.5 V
3.3 V up to
800 mA
R3
VINA
C1
4.7 mF
R1
R2
C2
10 mF
EN
FB
PS/SYNC
GND
C3
PGND
TPS63000
Figure 1. Typical Application Circuit for Adjustable Output Voltage Option
Inductor Selection
To properly configure the TPS6300X devices an inductor must be connected between pin L1 and pin L2. To
estimate the inductance value Equation 3 and Equation 4can be used.
8
Submit Documentation Feedback
TI [ TEXAS INSTRUMENTS ]
