Datasheet

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SWN
TPS65120
D1
L1
10
C1
2.2
V
IN
2.7 V to 5.5 V
V
GL
down to −18 V/2 mA
C3
100 nF
R4
R3
SWP
FBL
VMAIN
FBM
C5
220 nF
R6
R5
V
MAIN
3.0 V to 5.3 V/25 mA
C4
1
BOOT
VGH
C2
100 nF
V
GH
up to 20 V/2 mA
PGND
AGND
FBH
RUN
V
AUX
3.3 V/20 mA
EN
VIN
A
A
GATE
LDOIN
LDOOUT
C6
220 nF
R1
R2
µF
µF
Hµ
INDUCTOR SELECTION
TPS65120, TPS65121, TPS65123, TPS65124
SLVS531A – JUNE 2004 – REVISED MARCH 2005
APPLICATION INFORMATION (continued)
The larger the feed-forward capacitor the worse the load regulation of the device. Therefore, when concern for
load regulation is paramount, select a capacitor value as small as possible. Another possibility to further reduce
ripple voltage on VGH and VGL outputs is to increase output-capacitor values (C2, C3).
Figure 22. Typical Application
Since the control scheme of the TPS6512x device is inherently stable, the inductor value does not affect the
stability of the converter. To operate the TPS6512x properly at full performance, choose inductors in the range
8.2 µH to 10 µH.
The selection of the inductor is primarily based on the required output power. The variable peak current PWM
control scheme used in TPS6512x automatically adapts the peak inductor current (between 65mA typ. and
150mA typ.) depending on output power and input voltage.
At moderate loads, the converter typically operates with a peak inductor current in the range of 65mA to 100mA,
allowing the use of inductors in the 0603 case size. In order not to saturate the inductor when operating at a
higher output power, select an inductor with a higher saturation-current rating.
The inductor series in Table 1 from various suppliers have been used with the TPS6512x converter.
Table 1. List of Inductors
MANUFACTURER SERIES DIMENSIONS
LQ LB1608 1.6 x 0.8 x 0.8 = 1.02 mm
3
TAIYO YUDEN LQ CB2012 2.0 x 1.2 x 1.2 = 2.88 mm
3
LQ CBL2012 2.0 x 1.2 x 1.0 = 2.40 mm
3
GLF1608 1.6 x 0.8 x 0.8 = 1.02 mm
3
TDK
GLF2012 2.0 x 1.2 x 1.2 = 2.88 mm
3
18