el7581 Intersil Corporation, el7581 Datasheet - Page 13

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

Positive Charge Pump Design Considerations
A single stage charge pump is shown above. The maximum V
where:
• R
If additional stage is required, the LX switching signal is
recommended to drive the additional charge pump diodes.
The drive impedance at the LX switching is typically 150mΩ.
The figure on the next page illustrates an implementation for
two-stage positive charge pump circuit.
V
ON
voltage levels. For 12V supply, R
6V supply, R
V
ONN
OFF
(
max
5V to
and R
17V
)
≤
2
×
R
ON
ONP
21
V
R
C
3.3µF
DDCPP
22
OUT2
is typically 45Ω.
resistance values depend on the V
0.1µF
C
V
(1.32V)
- I
CPN
REF
OUT
13
×
V
DRVN
V
FBN
DDN
2
SSN
R
R
×
ON
ONP
ONN
(
R
ONN
is typically 33Ω. For
+
R
+
-
ONP
R
) - 2
ON
is 30 - 40Ω for V
DDP
×
V
DIODE
EL7581
ON
OSC
- I
output voltage is determined by the following equation:
OUT
DD
6V to 17V
×
------------------------------------------- -
0.5
×
F
S
1
×
C
+
-
CPP
+
-
- I
V
R
R
FBP
OUT
ONP
ONN
DRVP
V
V
FBP
DDP
SSP
×
----------------------------------------------- -
0.5
×
F
S
1
×
C
0.1µF
OUT1
R
12
C
CPP
R
11
C
2.2µF
OUT1
5V to
17V
V
ON