TPS62150A-Q1_15 Datasheet, PDF (14/35 Pages) Texas Instruments – TPS6215xA-Q1 3V to 17-V 1A Step-Down Converter with DCS-ControlTM

TPS62150A-Q1, TPS62153A-Q1
SLVSCC3 – MAY 2014
www.ti.com
11 Application and Implementation
11.1 Application Information
TPS62150xA-Q1 are synchronous switch mode step-down converters, able to convert a 3V to 17V input voltage
into a lower, 0.9V to 6V, output voltage, providing up to 1A load current. The following section gives guidance on
choosing external components to complete the power supply design. Application Curves are included for the
typical application shown below.
11.2 Typical Application
space
11.2.1 TPS62150A-Q1 Point-Of-Load Step Down Converter
(3 .. 17) V
10uF
3.3nF
PVIN
SW
AVIN
VOS
EN
PG
TPS62150A-Q1
SS/TR
FB
DEF
AGND
LOG
PGND
2.2 µH
3.3V / 1A
100k
1.21M
22uF
383k
Figure 16. Typical Schematic for 3.3V Step-Down Converter
11.2.1.1 Design Requirements
The step-down converter design can be adapted to different output voltage and load current needs by choosing
external components appropriate. The following design procedure is adequate for whole VIN, VOUT and load
current range of TPS62150A-Q1. Using Table 2, the design procedure needs minimum effort.
11.2.1.2 Detailed Design Procedure
11.2.1.2.1 Programming The Output Voltage
The TPS6215xA-Q1 can be programmed for output voltages from 0.9V to 6V by using a resistive divider from
VOUT to AGND. The voltage at the FB pin is regulated to 800mV. The value of the output voltage is set by the
selection of the resistive divider from Equation 6 (see Figure 13). It is recommended to choose resistor values
which allow a current of at least 2uA, meaning the value of R2 shouldn't exceed 400kΩ. Lower resistor values
are recommended for highest accuracy and most robust design. For applications requiring lowest current
consumption, the use of fixed output voltage versions is recommended.
R =R
1
2
ççèæ
V
OUT
V
REF
- 1_{÷÷øö}
(6)
In case the FB pin gets opened, the device clamps the output voltage at the VOS pin internally to about 7.4V.
11.2.1.2.2 External Component Selection
The external components have to fulfill the needs of the application, but also the stability criteria of the device's
control loop. The TPS6215xA-Q1 is optimized to work within a range of external components. The LC output
filter's inductance and capacitance must be considered together, creating a double pole, responsible for the
corner frequency of the converter (see Output Filter And Loop Stability). Table 2 can be used to simplify the
output filter component selection.
14
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