Datasheet

4 5 6 7 3 2 1
PGND/EP
VOUT
SS SYNC FB
VIN
EN AGND
V
IN
C
IN
2,3
10 PF
Enable
7V to 20V
U1
R
FBB
1.07k
LMZ22003TZ
3.3V
O
@ 3A
C
O
1,6
0.047 PF
C
O
5
220 PF
R
ENH
OPT
100Ö
R
ENT
42.2k
R
ENB
12.7k
R
FBT
3.32k
C
IN
1,5
0.047 PF
C
O
2
100 PF
OPT
+
D1 OPT
5.1V
SYNC
R
SN
OPT
1.50 kÖ
C
SS
0.47µF
C
IN
6 OPT
150 PF
+
R
FRA
OPT
23.7Ö
LMZ22003
www.ti.com SNVS658H –MARCH 2011–REVISED OCTOBER 2013
Figure 50. CCM and DCM Operating Modes
V
IN
= 12V, V
O
= 3.3V, I
O
= 3A/0.3A 2 μsec/div
The approximate formula for determining the DCM/CCM boundary is as follows:
I
DCB
≊V
O
*(V
IN
–V
O
)/(2*3.3 μH*f
SW(CCM)
*V
IN
) (13)
The inductor internal to the module is 3.3 μH. This value was chosen as a good balance between low and high
input voltage applications. The main parameter affected by the inductor is the amplitude of the inductor ripple
current (I
LR
). I
LR
can be calculated with:
I
LR P-P
=V
O
*(V
IN
- V
O
)/(3.3µH*f
SW
*V
IN
) (14)
Where V
IN
is the maximum input voltage and f
SW
is typically 812 kHz.
If the output current I
O
is determined by assuming that I
O
= I
L
, the higher and lower peak of I
LR
can be
determined.
Typical Application Schematic Diagram
Figure 51. Typical Application Schematic
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