Datasheet

OUT
FB
V
R1 = R2 × - 1
V
æ ö
ç ÷
è ø
RHPZ
2
(1 D) Vout
=
2 Iout L
- ´
´ ´
f
p
TPS63036
www.ti.com SLVSB76 –AUGUST 2012
(7)
With,
D =Duty Cycle in Boost mode
Note: The calculation must be done for the minimum input voltage which is possible to have in boost mode
Table 3. Inductor Selection
INDUCTOR VALUE COMPONENT SUPPLIER SIZE (LxWxH mm) Isat/DCR
1 µH TOKO 1286AS-H-1R0M 2x1.6x1.2 2.3A/78mΩ
1 µH Coilcraft XFL4020-102 4 x 4 x 2.1 5.1A/10.8 mΩ
1 µH Coilcraft XFL3012-102 3 x 3 x 1.2 2.2 A/35 mΩ
1.5µH TOKO, 1286AS-H-1R5M 2 x 1.6 x 1.2 4.4A/ 14.40mΩ
1.5µH Coilcraft, LPS3015-152MLC 3 x 3 x 1.5 2.1A/100mΩ
1.5µH TOKO, 1269AS-H-1R5M 2.5 x 2 x 1 2.1A/108mΩ
2.2µH TOKO D1286AS-H-2R2M 2 x 1.6 x 1.2 1.6A/192mΩ
Capacitor selection
Input Capacitor
At least a 10μF input capacitor is recommended to improve transient behavior of the regulator and EMI behavior
of the total power supply circuit. A ceramic capacitor placed as close as possible to the VIN and GND pins of the
IC is recommended.
Output Capacitor
For the output capacitor, use of a small ceramic capacitors placed as close as possible to the VOUT and GND
pins of the IC is recommended. If, for any reason, the application requires the use of large capacitors which can
not be placed close to the IC, use a smaller ceramic capacitor in parallel to the large capacitor. The small
capacitor should be placed as close as possible to the VOUT and GND pins of the IC. The recommended typical
output capacitor value is 30 µF.
There is also no upper limit for the output capacitance value. Larger capacitors will cause lower output voltage
ripple as well as lower output voltage drop during load transients.
When choosing input and output capacitors, it needs to be kept in mind, that the value of capacitance
experiences significant losses from their rated value depending on the operating temperature and the operating
DC voltage. It's not uncommon for a small surface mount ceramic capacitor to lose 50% and more of it's rated
capacitance. For this reason could be important to use a larger value of capacitance or a capacitor with higher
voltage rating in order to ensure the required capacitance at the full operating voltage.
Setting the Output Voltage
The output voltage of the TPS63036 is set by an external resistor divider. The resistor divider must be connected
between VOUT, FB and GND. When the output voltage is regulated, the typical value of the voltage at the FB pin
is 500mV. The maximum recommended value for the output voltage is 5.5V. The typical current into the FB pin is
0.01μA, and the voltage across the resistor between FB and GND, R
2
, is typically 500 mV. Based on these two
values, the recommended value for R2 should be lower than 100kΩ, in order to set the divider current at 5μA or
higher. From that, the value of the resistor connected between VOUT and FB, R1, depending on the needed
output voltage (V
OUT
), can be calculated using Equation 8:
(8)
A small capacitor C3=10pF, in parallel with R1 needs to be placed when using the Power Save Mode, to improve
considerably the output voltage ripple.
Copyright © 2012, Texas Instruments Incorporated Submit Documentation Feedback 17
Product Folder Links: TPS63036