EL7516
Typical Performance Curves
(Continued)
1
POWER DISSIPATION (W)
V
IN
= 3.3V
V
OUT
= 12V
I
OUT
= 50mA TO 300mA
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.1ms/DIV
JEDEC JESD51-7 HIGH EFFECTIVE THERMAL
CONDUCTIVITY TEST BOARD
870mW
θ
JA
=
200mV/DIV
SO
11 P8
5°
C/
W
M
0
25
50
75 85
100
125
AMBIENT TEMPERATURE (°C)
FIGURE 25. TRANSIENT RESPONSE - 1.2MHz
FIGURE 26. PACKAGE POWER DISSIPATION vs AMBIENT
TEMPERATURE
0.6
POWER DISSIPATION (W)
0.5
JEDEC JESD51-3 LOW EFFECTIVE THERMAL
CONDUCTIVITY TEST BOARD
486mW
0.4
0.3
0.2
0.1
0
θ
M
JA
=
P8
20
6°
C/
W
SO
0
25
50
75 85
100
125
AMBIENT TEMPERATURE (°C)
FIGURE 27. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE
Applications Information
The EL7516 is a high frequency, high efficiency boost
regulator operated at constant frequency PWM mode. The
boost converter stores energy from an input voltage source
and deliver it to a higher output voltage. The input voltage
range is 2.5V to 5.5V and output voltage range is 5V to 18V.
The switching frequency is selectable between 600KHz and
1.2MHz allowing smaller inductors and faster transient
response. An external compensation pin gives the user
greater flexibility in setting output transient response and
tighter load regulation. The converter soft-start characteristic
can also be controlled by external C
SS
capacitor. The SHDN
pin allows the user to completely shut-down the device.
the boost converter operates in two cycles. During the first
cycle, as shown in Figure 29, the internal power FET turns
on and the Schottky diode is reverse biased and cuts off the
current flow to the output. The output current is supplied
from the output capacitor. The voltage across the inductor is
V
IN
and the inductor current ramps up in a rate of V
IN
/ L, L
is the inductance. The inductance is magnetized and energy
is stored in the inductor. The change in inductor current is:
V
IN
∆I
L1
=
∆T1 ×
---------
L
D
-
∆T1
= -----------
F
SW
D
=
Duty Cycle
I
OUT
-
∆V
O
= ---------------
× ∆T
1
C
OUT
Boost Converter Operations
Figure 28 shows a boost converter with all the key
components. In steady state operating and continuous
conduction mode where the inductor current is continuous,
8
FN7333.3
IRF [ INTERNATIONAL RECTIFIER ]
