ISL97650 Intersil Corporation, ISL97650 Datasheet - Page 15

• Manufacturer Part Number: ISL97650
• Description: 4-Channel Integrated LCD Supply
• Manufacturer: Intersil Corporation

In voltage doubler configuration, the maximum V
given by the following equation:
For Voltage Tripler:
V
Negative Charge Pump Design Consideration
The negative charge pump consists of an internal switcher
M1, M2 which drives external steering diodes D2 and D3 via
a pump capacitor (C12) to generate the negative V
supply. An internal comparator (A1) senses the feedback
voltage on FBN and turns on M1 for a period up to half a
CLK period to maintain V
0.2V. External feedback resistor R6 is referenced to V
Faults on V
are detected by comparator (A2) and cause the fault
detection system to start a fault ramp on C
cause the chip to power down if present for more than the
time TFD (see "Electrical Specification" section and also
Figure “V
V
V
V
ON
ON_MAX(2x)
ON_MAX(3x)
ON
output voltage is determined by the following equation:
=
V
ON
FBP
OFF
=
FUNCTION DIAGRAM” on page 15).
=
•
3
⎛
⎜
⎝
2
which cause V
•
1
1.2MHz
(
•
+
V
(
0.9V
V
R
------ -
R
SUP
V
REF
8
9
SUP
⎞
⎟
⎠
–
(FBN)
–
V
DIODE
V
DIODE
15
FBN
in regulated operation at
)
–
)
to rise to more than 0.4V,
FB
2 I
Error
–
Control
•
2 I
•
OUT
OUT
DLY
•
(
•
3 R
FIGURE 16. V
pin which will
(
•
2 R
ON
•
ONH
OFF
is as
ONH
REF
+
VSUP
2 R
+
.
ISL97650
•
R
(EQ. 17)
(EQ. 18)
(EQ. 19)
M1
ON
ONL
ONL
FUNCTION DIAGRAM
VSUP
)
VSUP
)
D3
M3
M5
M2
M4
D2
D1
C1-
C1+
POUT
C2+
C2-
FBP
C21
C22
C7
C8
External Connections
C14
and Components
x2 Mode
x3 Mode
Both
R8
R9
November 28, 2006
FN9198.3