CAT661 Datasheet, PDF (10/16 Pages) Catalyst Semiconductor – High Frequency 100mA CMOS Charge Pump, Inverter/Doubler

CAT661
CAPACITOR SUPPLIERS
The following manufacturers supply low-ESR capacitors:
Manufacturer Capacitor Type Phone
WEB
Email
Comments
AVX/Kyocera TPS/TPS3
843-448-9411 www.avxcorp.com [e-mail] Tantalum
Vishay/Sprague 595
402-563-6866 www.vishay.com
—
Aluminum
Sanyo
MV-AX, UGX 619-661-6835 www.sanyo.com
[e-mail] Aluminum
Nichicon
F55
847-843-7500 www.nichicon-us.com
—
Tantalum
HC/HD
Aluminum
Capacitor manufacturers continually introduce new series
and offer different package styles. It is recommended
that before a design is finalized capacitor manufacturers
should be surveyed for their latest product offerings.
CONTROLLING LOSS IN CAT661 APPLICATIONS
There are three primary sources of voltage loss:
1. Output resistance
VLOSS = ILOAD x ROUT, where ROUT is the
CAT661 output resistance and ILOAD is the
load current.
2. Charge pump (C1) capacitor ESR:
VLOSSC1 ≈ 4 x ESRC1 x ILOAD, where
ESRC1 is the ESR of capacitor C1.
3. Output or reservoir (C2) capacitor ESR:
VLOSSC2 = ESRC2 x ILOAD, where ESRC2
is the ESR of capacitor C2.
Increasing the value of C2 and/or decreasing its ESR will
reduce noise and ripple.
The effective output impedance of a CAT661 circuit is
approximately:
Rcircuit ≈ Rout 661 + (4 x ESRC1) + ESRC2
VOLTAGE INVERSION POSITIVE-TO-NEGATIVE
The CAT661 easily provides a negative supply voltage
from a positive supply in the system. Figure 8 shows a
typical circuit. The LV pin may be left floating for positive
input voltages at or above 3.3V.
TYPICAL APPLICATIONS
Doc. No. 5003, Rev. J
NC
+
C1
1
BOOST/FC
8
V+
2
7
CAP+
OSC
3
CAT661 ₆
GND
LV
4 _CAP-
OUT ⁵
VIN
1.5V to 5.5V
C2 ^{VOUT = -VIN}
+
Figure 8: Voltage Inverter
10