LM2663M National Semiconductor, LM2663M Datasheet - Page 8

• Manufacturer Part Number: LM2663M
• Description: DC/DC Charge Pump Converter IC
• Manufacturer: National Semiconductor

Specifications of LM2663M

• Output Current: 200mA
• No. Of Pins: 8
• Power Dissipation Pd: 735mW
• Mounting Type: Surface Mount
• Peak Reflow Compatible (260 C): No
• Supply Voltage Max: 5.5V
• Leaded Process Compatible: No
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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Application Information
CAPACITOR SELECTION
As discussed in the Simple Negative Voltage Converter section, the output resistance and ripple voltage are dependent on the
capacitance and ESR values of the external capacitors. The output voltage drop is the load current times the output resistance,
and the power efficiency is
Where I
resistance, the two external capacitors and their ESRs.
Low ESR capacitors ( Table 3 ) are recommended for both capacitors to maximize efficiency, reduce the output voltage drop and
voltage ripple. For convenience, C
The output resistance varies with the oscillator frequency and the capacitors. In Figure 3 , the output resistance vs. oscillator fre-
quency curves are drawn for four difference capacitor values. At very low frequency range, capacitance plays the most important
role in determining the output resistance. Once the frequency is increased to some point (such as 100 kHz for the 47 µF capaci-
tors), the output resistance is dominated by the ON resistance of the internal switches and the ESRs of the external capacitors.
A low value, smaller size capacitor usually has a higher ESR compared with a bigger size capacitor of the same type. Ceramic
capacitors can be chosen for their lower ESR. As shown in Figure 3 , in higher frequency range, the output resistance using the
10 µF ceramic capacitors is close to these using higher value tantalum capacitors.
Q
(V+) is the quiescent power loss of the IC device, and I
Nichicon Corp.
AVX Corp.
Sprague
Sanyo
Murata
Taiyo Yuden
Tokin
Manufacturer
FIGURE 3. Output Source Resistance vs Oscillator Frequency
1
and C
(800)-831-9172
(800)-348-2496
(408)-432-8020
(708)-843-7500
(803)-448-9411
(207)-324-4140
(619)-661-6835
TABLE 3. Low ESR Capacitor Manufacturers
(Continued)
Phone
2
are usually chosen to be the same.
PL, PF series, through-hole aluminum electrolytic
TPS series, surface-mount tantalum
593D, 594D, 595D series, surface-mount tantalum
OS-CON series, through-hole aluminum electrolytic
Ceramic chip capacitors
Ceramic chip capacitors
Ceramic chip capacitors
8
L
2
R
OUT
is the conversion loss associated with the switch on-
Capacitor Type
DS100003-36