Ceramic capacitors are recommended because they
have low ESR and the lowest profile. Typical ceramic
capacitors are the C3225X5R series from TDK and
JMK325 series from Taiyo Yuden. See Table 3 for more
information on the manufacturers who provide surface-
mount ceramic capacitors.
PLL Compensation
In most applications, the recommended compensation
component values shown in Figure 4 will give optimal
system performance. If no backplane clock is used,
connect PLLC to REF.
_____________Applications Information
Increasing V
OUT
Above 5.5V
For V
OUT1
output voltages above 5.5V, connect the
supplemental charge pump circuit shown in Figure 5.
The connection shown supplies a 10V 150mA output,
but other voltages from 2 x V
IN
to 10V can be set by
selecting the appropriate values for R1 and R2 (see
DC-DC 1 Output
section). C2–C4 are shown as parallel
combinations of 3.3µF ceramic capacitors so that a
1.1mm height restriction can be met. If height is not
restricted, then larger values can be used instead of
parallel capacitor combinations.
3.3V to -20V Charge-Pump Configuration
For applications requiring negative voltages down to
-20V, an inverting charge-pump block can be added to
the V
OUT2-
output (Figure 6). Typical values for C
F
and
C
OUT
are 0.47µF to 1µF and 4.7µF to 10µF, respective-
ly. As a general rule, C
OUT
should be ten times greater
than C
F
. This circuit operates as follows:
1) During the first PFM cycle, the voltage at V1 is
charged by inductor L2 to some fraction of its final
steady-state voltage, in the normal manner described
in the
Detailed Description
.
2) During the first half of subsequent PFM cycles, pin
LX2P is pulled to V
INP
, and capacitor C
F
is charged
to (V
INP
+V
1
- V
D
), where V
D
is a diode forward
voltage.
3) During subsequent second half-cycles when LX2P
flies negatively below V1, capacitor C
F
transfers
some of its energy to output capacitor C
OUT
, which
then is charged to a negative voltage of approxi-
mately (V
INP
+ 2 x V
1
- 2x V
D
).
4) This process continues until V
OUT
reaches the
desired voltage, as determined by the ratio of the
FB2- feedback resistors.
5) During steady-state (in-regulation) operation, the
magnitude of the voltage at LX2P is equal to
(V
OUT
/ 2 - V
INP
/ 2 + V
D
), which must be limited to
less than 10V.
MAX1664
Active-Matrix Liquid Crystal Display
(AMLCD) Supply
______________________________________________________________________________________ 13
MANUFACTURER PHONE FAX
Dale Inductors (605) 668-4131 (605) 665-1627
Sumida USA (847) 956-0666 (847) 956-0702
Central Semiconductor (516) 435-1110 (516) 435-1824
International Rectifier (310) 322-3331 (310) 322-3232
TDK (847) 390-4373 (847) 390-4428
Vishay/Vitramon (203) 268-6261 (203) 452-5670
Table 3. Component Manufacturers
(18 Seiten)
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
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