isl97701 Intersil Corporation, isl97701 Datasheet - Page 9

• Manufacturer Part Number: isl97701
• Description: Boost Regulator With Integrated Schottky And Input Disconnect Switch
• Manufacturer: Intersil Corporation

Typical Application
Typical applications are passive- or active-matrix organic
light emitting diode displays (PMOLED, AMOLED) in
handheld devices. Applications with low power or screen
saver mode is directly supported.
Components Selection
The input capacitance is normally 10µf~15µF and the output
capacitor is 3.3µf to 6.6µF. X5R or X7R type of ceramic
capacitor with correct voltage rating is recommended. The
output capacitor value will affect the output voltage ripple.
Higher value of the output capacitor, lower ripple of the
output voltage.
When choosing an inductor, make sure the inductor can
handle the average and peak currents given by Equations 3,
4 and 5 (80% efficiency assumed):
Where:
• ΔI
• L inductance in H
• f
Optimal combination of the boost inductor L and the output
capacitor C
I
I
ΔI
LAVG
LPK
L
OSC
J2
GND_IN
J1
VDD_IN
J4
NSYNC
=
L
=
is the peak-to-peak inductor current ripple in Amperes
V
-------------------------------------------------- -
=
I
IN
L V
switching frequency, typically 1.0MHz
LAVG
I
--------------------------------- -
⋅
OUT
⋅
VDD
0.8 V
(
OUT
OUT
V
JP3
OUT
+
⋅
⋅
V
1
-- -
2
⋅
are listed in Table 2:
OUT
IN
⋅
f
–
OSC
ΔI
100n
V
L
IN
)
C1
VDD
9
10µ
C2
4.7µ/10V
C9
FIGURE 18. ISL97701 APPLICATION BOARD
1
2
3
4
5
U1
GND
VDDOUT
VDD
NSYNC
FB
(EQ. 3)
(EQ. 4)
(EQ. 5)
ISL97701
6.8µH
L1
ISL97701
VOUT
GND
NEN
NC
LX 10
9
8
7
6
Recommended Inductor and Ceramic capacitor
manufacturers are listed in Table 3:
PCB layout Considerations
The layout is very important for the converter to function
properly. To ensure the high pulse current in the power
ground does not interfere with the sensitive feedback
signals, the current loops (V
V
DFN package, there is no separated GND. All return GNDs
should be connected in GND pin but with no sharing branch.
The heat of the IC is mainly dissipated through the thermal
pad. Maximizing the copper area connected to the thermal
pad is preferable. In addition, a solid ground plane is helpful
for the EMI performance.
Sumida: www.sumida.com
TDK:
Toko:
OUT
TABLE 2. OPTIMAL COMBINATION OF BOOST INDUCTOR L
TABLE 3. RECOMMENDED INDUCTOR AND CERAMIC
INDUCTOR (µH)
-C
390k
39k
R6
R1
OUT
INDUCTOR
www.tdk.co.jp
www.tokoam.com
4.7
6.8
10
15
-GND) should be as short as possible. For the
AND OUTPUT CAPACITOR C
MANUFACTURERS
IN
Taiyo Yuden: www.t-yuden.com
AVX:
Murata:
-L1-LX-GND, and V
MIN
C8
100n
2.2
3.3
4.7
6.8
3.3µF/50V
R3
OPEN
CAPACITOR (µF)
CERAMIC CAPACITOR
C7
VDD
OUT
J1
www.avxcorp.com
www.murata.com
2
C6
1nF/50V
MAX
J7
VOUT
J3
GND_OUT
J6
NEN
IN
10
10
10
10
April 23, 2007
-L1-
FN6474.0