ICL7660SIBAZ Intersil, ICL7660SIBAZ Datasheet - Page 9

• Manufacturer Part Number: ICL7660SIBAZ
• Description: IC VOLTAGE CONVERTER CMOS 8-SOIC
• Manufacturer: Intersil
• Type: Switched Capacitor (Charge Pump), Doubler, Invertingr

Specifications of ICL7660SIBAZ

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Frequency - Switching: 10kHz, 35kHz
• Voltage - Input: 1.5 ~ 12 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Primary Input Voltage: 12V
• No. Of Outputs: 1
• Output Voltage: 22.8V
• Output Current: 20mA
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +85°C
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Output: -
• Power - Output: -

every cycle. In a typical application where f
C = C
R
Since the ESRs of the capacitors are reflected in the output
impedance multiplied by a factor of 5, a high value could
potentially swamp out a low 1/(f
increase in switching frequency or filter capacitance ineffective.
Typical electrolytic capacitors may have ESRs as high as 10Ω.
R
Since the ESRs of the capacitors are reflected in the output
impedance multiplied by a factor of 5, a high value could
potentially swamp out a low 1/(f
increase in switching frequency or filter capacitance ineffective.
Typical electrolytic capacitors may have ESRs as high as 10Ω.
Output Ripple
ESR also affects the ripple voltage seen at the output. The
total ripple is determined by 2 voltages, A and B, as shown in
Figure 14. Segment A is the voltage drop across the ESR of
C
flow into C
flowing out of C
2• I
B is the voltage change across C
the cycle when C
is l
of these voltage drops:
Again, a low ESR capacitor will reset in a higher
performance output.
Paralleling Devices
Any number of ICL7660 and ICL7660A voltage converters
may be paralleled to reduce output resistance. The reservoir
capacitor, C
its own pump capacitor, C
would be approximately:
O
O/
2
OUT
at the instant it goes from being charged by C
OUT
≅ 46 + 20 + 5 (ESR
≅ 46 + 20 + 5 (ESR
1
= C
• t2/C
, hence the total drop is 2• I
2
2
) to being discharged through the load (current
2
= 10µF:
, serves all devices while each device requires
2
V. The peak-to-peak ripple voltage is the sum
2
). The magnitude of this current change is
2
supplies current to the load. The drop at B
C
C
)
)
1
. The resultant output resistance
9
PUMP
PUMP
2
OUT
during time t
• C
• C
1
1
• eSR
) term, rendering an
) term, rendering an
OSC
C2
= 10kHz and
2
V. Segment
, the half of
1
(current
Cascading Devices
The ICL7660 and ICL7660A may be cascaded as shown to
produced larger negative multiplication of the initial supply
voltage. However, due to the finite efficiency of each device,
the practical limit is 10 devices for light loads. The output
voltage is defined by:
V
where n is an integer representing the number of devices
cascaded. The resulting output resistance would be
approximately the weighted sum of the individual ICL7660
and ICL7660A R
Changing the ICL7660/ICL7660A Oscillator
Frequency
It may be desirable in some applications, due to noise or
other considerations, to increase the oscillator frequency.
This is achieved by overdriving the oscillator from an
external clock, as shown in Figure 17. In order to prevent
possible device latchup, a 1kΩ resistor must be used in
series with the clock output. In a situation where the
designer has generated the external clock frequency usinP.7(osc5.8(sin)
OUT
= -n (V
IN
),
OUT
values.
October 10, 2005
FN3072.7