MAX619 Ver la hoja de datos (PDF) - Maxim Integrated
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MAX619 Datasheet PDF : 7 Pages
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Regulated 5V Charge-Pump
DC-DC Converter
__________Applications Information
Capacitor Selection
Charge-Pump Capacitors C1 and C2
The values of charge-pump capacitors C1 and C2 are
critical to ensure adequate output current and avoid
excessive peak currents. Use values in the range of
0.22µF to 1.0µF. Larger capacitors (up to 50µF) can
be used, but larger capacitors will increase output rip-
ple. Ceramic or tantalum capacitors are recommend-
ed.
Input and Output Capacitors, C3 and C4
The type of input bypass capacitor (C3) and output fil-
ter capacitor (C4) used is not critical, but it does affect
performance. Tantalums, ceramics, or aluminum elec-
trolytics are suggested. For smallest size, use Sprague
595D106X0010A2 surface-mount capacitors, which
measure 3.7mm x 1.8mm (0.146in x 0.072in). For low-
est ripple, use large, low effective-series-resistance
(ESR) ceramic or tantalum capacitors. For lowest cost,
use aluminum electrolytic or tantalum capacitors.
Figure 2 shows the component values for proper oper-
ation using minimal board space. The input bypass
capacitor (C3) and output filter capacitor (C4) should
both be at least 10µF when using aluminum electrolyt-
ics or Sprague’s miniature 595D series of tantalum chip
capacitors.
When using ceramic capacitors, the values of C3 and
C4 can be reduced to 2µF and 1µF, respectively. If the
input supply source impedance is very low, C3 may not
be necessary.
Many capacitors exhibit 40% to 50% variation over
temperature. Compensate for capacitor temperature
coefficient by selecting a larger nominal value to
ensure proper operation over temperature. Table 1 lists
capacitor suppliers.
C2
0.22µF
2
CELLS
C3
10µF
1
C1+
4
C2+
MAX619
8 C1–
5
C2–
2
IN
7
SHDN
6
GND
3
OUT
C1
0.22µF
5V ±4%
@ 20mA
C4
10µF
Figure 2. Two-Cell to 5V Application Circuit
Table 1. Capacitor Suppliers
SUPPLIER
Murata Erie
Sprague Electric
(smallest size)
PHONE NUMBER
(814) 237-1431
(603) 224-1961
(207) 327-4140
FAX NUMBER
(814) 238-0490
(603) 224-1430
(207) 324-7223
CAPACITOR
GRM42-6Z5U10M50
GRM42-6Z5U22M50
RPI123Z5U105M50V
RPE121Z5U104M50V
595D106X0010A2
* Note: (SM) denotes surface-mount component, (TH) denotes through-hole component.
CAPACITOR TYPE*
0.1µF ceramic (SM)
0.22µF ceramic (SM)
1.0µF ceramic (TH)
0.1µF ceramic (TH)
10µF tantalum (SM)
6 ________________________________________________________________________________________
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