Datasheet

OUT FB
R1 R1
V = V 1 + = 0.8 V 1 +
R2 R2
æ ö æ ö
´ ´
ç ÷ ç ÷
è ø è ø
FB
FB
V
0.8 V
R2 = = 160 kΩ
I 5 μA
»
OUT OUT
FB
V V
R1 = R2 1 = R2 1
V 0.8V
æ ö
æ ö
´ - ´ -
ç ÷
ç ÷
è ø
è ø
2.5V to 6V
C1
10 Fm
C3
C4
10nF
10nF
Vout
1.2V/3A
Vin
PVIN
PVIN
EN FB
L1
470nH
C2
22 Fm
R1
75k
SW
TPS62090
SW
Power Good
AVIN
R2
150k
SS
R3
500k
AGND
PG
VOS
FREQ
CP
CN
1
2
3
4
5
6
PGND PGND
7
8
9
10
11
12
13
14 15
16
TPS62090, TPS62091
TPS62092, TPS62093
SLVSAW2A –MARCH 2012–REVISED MARCH 2012 www.ti.com
Setting the Output Voltage
The output voltage is set by an external resistor divider according to the following equations:
(9)
(10)
(11)
When sizing R2, in order to achieve low quiescent current and acceptable noise sensitivity, use a minimum of 5
µA for the feedback current I
FB
. Larger currents through R2 improve noise sensitivity and output voltage
accuracy. Lowest quiescent current and best output voltage accuracy can be achieved with the fixed output
voltage versions. For the fixed output voltage versions, the FB pin can be left floating or connected to GND to
improve the thermal package performance.
Layout Guideline
It is recommended to place all components as close as possible to the IC. The VOS connection is noise sensitive
and needs to be routed as short and directly to the output terminal of the inductor. The exposed thermal pad of
the package, analog ground (pin 6) and power ground (pin 14, 15) should have a single joint connection at the
exposed thermal pad of the package. This minimizes switch node jitter. The charge pump capacitor connected to
CP and CN should be placed close to the IC to minimize coupling of switching waveforms into other traces and
circuits. Refer to the evaluation module User Guide (SLVU670) for an example of component placement, routing
and thermal design.
TYPICAL APPLICATIONS
Figure 29. 1.2 V Adjustable Version Operating at 2.8 MHz
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Product Folder Link(s): TPS62090 TPS62091 TPS62092 TPS62093