TC1220 Microchip Technology, TC1220 Datasheet - Page 6

• Manufacturer Part Number: TC1220
• Description: (TC1219) Switched Capacitor Voltage Converters with Shutdown in SOT Packages
• Manufacturer: Microchip Technology

TC1219/TC1220
4.3
In order to maintain the lowest output resistance and
output ripple voltage, it is recommended that low ESR
capacitors be used. Additionally, larger values of C1
will lower the output resistance and larger values of
C2 will reduce output ripple. (Equation 4-1(b) and
Equation 4-3).
Table 4-1 shows various values of C1 and the
corresponding output resistance values @ +25°C. It
assumes a 0.1Ω ESR
shows the output voltage ripple for various values of
C2. The V
current and 0.1Ω ESR
TABLE 4-1:
TABLE 4-2:
4.4
The V
reduce AC impedance and minimize noise effects due
to
recommended capacitor depends on the configuration
of the TC1219/TC1220.
DS21366B-page 6
C1 (µF)
C2 (µF)
the
3.3
3.3
IN
10
30
10
30
1
1
Capacitor Selection
Input Supply Bypassing
input should be capacitively bypassed to
internal
RIPPLE
OUTPUT RESISTANCE VS.
C1 (ESR = 0.1 Ω )
OUTPUT VOLTAGE RIPPLE
VS. C2 (ESR = 0.1 Ω )
I
values assume 10mA output load
OUT
V
switching
RIPPLE
R
TC1219
TC1219
C2
C1
OUT
19.3
10mA
100
419
128
.
42
25
44
16
and 2Ω R
(Ω)
(mV)
of
the
SWITCH
V
RIPPLE
R
TC1220
TC1220
device
OUT
19.4
17.5
145
. Table 4-2
45
25
45
16
7
(Ω)
(mV)
The
4.5
The TC1219/TC1220 is enabled when SHDN is high,
and disabled when SHDN is low. This input cannot be
allowed to float. (If SHDN is not required, see the
TCM828/829 data sheet.) The SHDN input can be only
driven to 0.5V above V
flows.
4.6
The most common application for charge pump
devices is the inverter (Figure 4-3). This application
uses two external capacitors: C1 and C2 (plus a power
supply bypass capacitor, if necessary). The output is
equal to -V
Refer to Table 4-1 and Table 4-2 for capacitor
selection.
FIGURE 4-3:
3
5
1
2
Device
TC1219
TC1220
IN
OUT
C1 –
SHDN
Shutdown Input
Voltage Inverter
TC1219
TC1220
IN
plus any voltage drops due to loading.
GND
C1 +
C3
6
4
VOLTAGE INVERTER
TEST CIRCUIT
10µF
3.3µF
C1
 2002 Microchip Technology Inc.
IN
C1
+
to avoid significant current
+
10µF
3.3µF
C2
+
C2
V
R
IN
L
10µF
3.3µF
C3
V
OUT