el7516 Intersil Corporation, el7516 Datasheet - Page 11

• Manufacturer Part Number: el7516
• Description: 600khz/1.2mhz Pwm Step-up Regulator
• Manufacturer: Intersil Corporation

where:
ΔI
V
f
I
D = MOSFET turn-on ratio:
Table 1 gives typical maximum I
switching frequency and 22µH inductor:
D
S
L-AVG
DIODE
L
I
I
ΔI
= switching frequency, 600kHz or 1.2MHz
=
L
L-AVG
=
L
= MOSFET current limit
1
= inductor ripple current
V
------------------------------------------------------------------------------
–
V
=
IN
--------------------------------------------
V
IN
L
= Schottky diode forward voltage, typically, 0.6V
2.5
2.5
2.5
3.3
3.3
3.3
= average inductor current
OUT
5
5
I
-------------
1 D
×
×
OUT
(V)
–
[
(
(
V
V
V
+
O
O
IN
V
+
+
DIODE
V
V
DIODE
DIODE
)
) V
TABLE 1.
V
×
–
OUT
f
11
S
12
12
12
5
9
5
9
9
IN
(V)
]
OUT
values for 1.2MHz
I
OMAX
570
325
250
750
435
330
650
490
(EQ. 10)
(EQ. 8)
(EQ. 9)
(mA)
EL7516
Thermal Performance
The EL7516 uses a fused-lead package, which has a
reduced θ
on a two-layer board. Maximizing copper around the ground
pins will improve the thermal performance.
This device also has internal thermal shut-down set at
around +130°C to protect the component.
Layout Considerations
To achieve highest efficiency, best regulation and the most
stable operation, a good printed circuit board layout is
essential. It is strongly recommended that the demoboard
layout be followed as closely as possible. Use the following
general guidelines when laying out the print circuit board:
The demo board is a good example of layout based on these
principles; it is available upon request.
Differences Between EL7516 and ISL97516
ISL97516 is the replacement for EL7516, and it is pin-to-pin
compatible to EL7516, but there are differences between the
two parts, as shown in the Table 2:
From Table 2, it shows that ISL97516 can provide more
output current at the same conditions, and work in higher
ambient temperature. The fixed logic level also helps reduce
the system design complexity.
Current Limit
Over-Temperature
Protection
Logic High or Low Level Refer to Ground,
1. Place C
2. Keep the C
3. Keep the two high current paths a) from C
4. High current traces should be as short and as wide as
5. Place the feedback resistor close to the FB pin to avoid
6. Place the compensation network close to the COMP pin.
TABLE 2. DIFFERENCES BETWEEN EL7516 AND ISL97516
supply bypass capacitor of the device.
possible.
the LX pin and GND and b) from C
C
possible.
noise pickup.
2
as short as possible.
JA
4
of 100°C/W on a four-layer board and 115°C/W
as close to the V
1
ground, GND pin and C
2.0A (typical value)
+150°C
Fixed.
ISL97516
DD
pin as possible. C
1
2
through L
ground as close as
1.5A (typical value)
+130°C
Refer to input
voltage, Varying
1
through L
EL7516
October 9, 2007
1
, D
4
is the
FN7333.6
1
, and
1
, to