3/5 Rev. A /01-2010
6. Operating Instructions
(6.1) Connect Vin to the positive point of DC power supply and GND to supply ground.
(6.2) Connect -Vout to the positive point of E-load and GND to supply ground or parallel an
appropriate resistor to pull up the loading.
(6.3) Importing a logic signal to EN pin will enable the AME5150. Logic high (V
EN
>1.5V) switches on
AME5150, logic low puts it into low current shutdown mode.
7. Application Information
(7.1) Setting Output Voltage & Current
(7.1 1) Output Voltage
The regulated output voltage is set by an external resistor divider (R4 and R5 in Figure 2.)
from the output to the V
NFB
pin and is determined by:
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
×
+
+
×
−
=
NFB
NFB
OUT
I
R
R
R
V
V
4
5
4
)
1
(
Where V
NFB
equals -1.23V and I
NFB
equals 2uA for AME5150.
(7.1.2) Duty Cycle & Output Current
According to input and output voltage to calculate duty cycle and switching frequency.
Selecting feasible inductance can calculate output current by following equations.
SW
DIODE
OUT
IN
DIODE
OUT
V
V
V
V
V
V
D
−
+
−
+
=
)
)(
(
)
(
Max
ON
DS
Typ
CL
SW
R
I
V
×
=
}
2
)
(
{
)
1
(
(min)
(max)
fL
V
V
D
I
D
I
SW
IN
CL
LOAD
−
×
−
×
−
=
Where:
V
IN
is input voltage
V
OUT
is output voltage
T
OFF
is the duration of switch off; for AME5150 T
OFF
is fixed 400ns
V
DIODE
is the forward voltage of Schottky Diode
V
SW
is (“switch current limit” times “switch on-Resistance”); See the datasheet to have
L is the inductance
f is the switching frequency
I
LOAD(max)
means the maximum ability of output driving
