el7581 Intersil Corporation, el7581 Datasheet - Page 15

• Manufacturer Part Number: el7581
• Description: 3-channel Dc/dc Converter
• Manufacturer: Intersil Corporation

Two-Stage Negative Charge Pump Circuit
The maximum V
R
Where V
Over-Temperature Protection
An internal temperature sensor continuously monitors the
die temperature. In the event that die temperature exceeds
the thermal trip point, the device will shut down and disable
itself. The upper and lower trip points are typically set to
130°C and 90°C respectively.
PCB Layout Guidelines
Careful layout is critical in the successful operation of the
application. The following layout guidelines are
recommended to achieve optimum performance.
• V
• Place the boost converter diode and inductor close to the
• Place the boost converter output capacitor close to the
• Locate feedback dividers close to their respected
• Place the charge pump feedback resistor network after the
V
V
V
21
OFF
OFF
DDN
to the pins.
LX pins.
PGND pins.
feedback pins to avoid switching noise coupling into the
high impedance node.
diode and output capacitor node to avoid switching noise.
REF
and R
(
max
=
- N
and V
–
REF
V
×
22
)
REF
V
≥
LX
I
determine V
is nominal 1.310V.
OUT
DDB
(
×
max
OFF
R
--------- -
R
×
21
22
bypass capacitors should be placed next
2
)
output voltage for N+1 stage charge pump is:
+
×
N
(
R
×
OFF
ONN


2
15
×
output voltage:
+
V
R
DIODE
ONP
V
R
R
+
DRVN
V
-
DDN
ONP
ONN
SSN
FBN
)
+
+
I
2
OUT
×
V
DIODE
×
--------------------------------------------
0.5
C
CPN
×
5V-17V
- I
F
S
OUT
1
×
C
C
CPN
×
OUT2
EL7581
--------------------------------------------
0.5
+
×
I
F
OUT
S
1
×
• Thermal pad needs to be connected to PGND pins
• All low-side feedback resistors should be connected
A demo board is available to illustrate the proper layout
implementation.
×
C
CPN
----------------------------------------------- -
0.5
electrically, and it should be soldered to PCB with thermal
vias connecting to ground plane for maximum heat
dissipation.
directly to V
ground close at one point only.
V
LX
C
×
CPN
C
- I
F
OUT2
S
OUT
1
×
C
OUT2
×
SSB
----------------------------------------------- - -
0.5
V
. V
×


REF
F
SSB
R
R
S
21
22
1
×
C
V
should be connected to the power
OUT2
OFF