TPS62065_15 Datasheet, PDF (12/28 Pages) Texas Instruments – TPS6206x 3-MHz, 2-A, Step-Down Converter in 2-mm × 2-mm SON Package

TPS62065, TPS62067
SLVS833C – MARCH 2010 – REVISED JULY 2015
9 Application and Implementation
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NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The TPS62065 and TPS62067 are highly efficient synchronous step down DC/DC converters providing up to 2-A
output current.
9.2 Typical Application
V_IN = 2.9 V to 6 V
PVIN
AVIN
C_IN
10 µF
EN
MODE
AGND
PGND
L
1.0 mH
SW
R₁
360 kΩ
FB
R₂
180 kΩ
V_OUT = 1.8 V
up to 2 A
C_ff
22 pF
C_OUT
10 µF
Figure 9. TPS62065 1.8-V Adjustable Output Voltage Configuration
9.2.1 Design Requirements
The device operates over an input voltage range from 2.9 V to 6 V. The output voltage is adjustable using an
external feedback divider.
9.2.2 Detailed Design Procedure
9.2.2.1 Output Voltage Setting
The output voltage can be calculated to:
V_OUT
=
V_REF
´
æç_{1 +}
è
R₁
R₂
ö
÷
ø
R₁ =
æ
ç
V_OUT
è ^VREF
-
ö
1_÷
ø
´
R₂
with an internal reference voltage V_REF typically 0.6 V.
To minimize the current through the feedback divider network, R₂ should be within the range of 120 kΩ to 360
kΩ. The sum of R₁ and R₂ should not exceed approximately 1 MΩ, to keep the network robust against noise. An
external feed-forward capacitor C_ff is required for optimum regulation performance. Lower resistor values can be
used. R₁ and C_ff places a zero in the loop. The right value for C_ff can be calculated as:
1
f_z = _{2 ´ p ´ R1 ´ Cff} = 25 kHz
1
C_ff = _{2 ´ p ´ R1 ´ 25 kHz}
9.2.2.2 Output Filter Design (Inductor and Output Capacitor)
The internal compensation network of TPS6206x is optimized for a LC output filter with a corner frequency of:
f_c = _{2 ´ p ´}
1
(1μH ´10μF)
= 50kHz
(2)
12
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