Datasheet

22uF
Vout / 2A
10uF
1 / 2.2 µH
(3 .. 17)V
3.3nF
PVIN
AVIN
EN
SS/TR
DEF
FSW
SW
VOS
PG
FB
AGND
PGND
R3
R1
R2
TPS62140A
TPS62140
PVIN
AVIN
EN
SS/TR
DEF
FSW
SW
VOS
PG
FB
AGND
PGND
2.2µH
(3 .. 13.7)V
10uF
383k
1.21M
22uF
-3.3V
10uF
3.3nF
maxINOUTIN
VVV £+
TPS62140, TPS62140A
TPS62141, TPS62142, TPS62143
www.ti.com SLVSAJ0B –NOVEMBER 2011–REVISED JUNE 2013
Application Example As Inverting Power Supply
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The TPS62140 can be used as inverting power supply by rearranging external circuitry as shown in Figure 50.
As the former GND node now represents a voltage level below system ground, the voltage difference between
V
IN
and V
OUT
has to be limited for operation to the maximum supply voltage of 17V (see Equation 16).
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(16)
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Figure 50. –3.3V Inverting Power Supply
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The transfer function of the inverting power supply configuration differs from the buck mode transfer function,
incorporating a Right Half Plane Zero additionally. The loop stability has to be adapted and an output
capacitance of at least 22µF is recommended. A detailed design example is given in SLVA469.
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Active Output Discharge
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The TPS62140A pulls the PG pin Low, when the device is shut down by EN, UVLO or thermal shutdown.
Connecting PG to Vout through a resistor can be used to discharge Vout in those cases (see Figure 51). The
discharge rate can be adjusted by R3, which is also used to pull up the PG pin in normal operation. For reliability,
keep the maximum current into the PG pin less than 10mA.
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Figure 51. Discharge Vout through PG pin
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