TC682EOA Microchip Technology, TC682EOA Datasheet - Page 5

• Manufacturer Part Number: TC682EOA
• Description: IC INVERTING VOLT DOUBLER 8SOIC
• Manufacturer: Microchip Technology
• Type: Switched Capacitor (Charge Pump), Doubler, Invertingr

Specifications of TC682EOA

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: -4.8 ~ -11 V
• Current - Output: 10mA
• Frequency - Switching: 12kHz
• Voltage - Input: 2.4 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Power - Output: 470mW
• Primary Input Voltage: 5.5V
• No. Of Outputs: 1
• Output Current: 10mA
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +85°C
• Peak Reflow Compatible (260 C): Yes
• Switching Frequency Max: 12kHz
• Function: Inverting
• Output Voltage: - 10 V
• Maximum Operating Temperature: 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

4.0
4.1
The most common application of the TC682 is as a
charge pump voltage converter which provides a
negative output of two times a positive input voltage
(Figure 4-1).
FIGURE 4-1:
4.2
The output resistance of the TC682 is determined, in
part, by the ESR of the capacitors used. An expression
for R
Assuming all switch resistances are approximately
equal:
R
μF low ESR capacitors. The fixed term (16R
about 80-90Ω. It can be seen easily that increasing or
decreasing values of C1 and C2 will affect efficiency by
changing R
term can quickly become dominant with large electro-
lytic capacitors. Table 4-1 shows R
values of C1 and C2 (assume 0.5Ω ESR). C1 must be
rated at 6VDC or greater while C2 and C3 must be
rated at 12VDC or greater.
© 2006 Microchip Technology Inc.
R
R
OUT
OUT
OUT
C
C
1
2
+
+
OUT
= 2(R
= 16R
is typically 140Ω at +25°C with V
+2(R
+1/(f
+ESR
+1/(f
22 μF
22 μF
TYPICAL APPLICATIONS
Negative Doubling Converter
Capacitor Selection
is derived as shown below:
SW1
PUMP
SW
SW1
PUMP
OUT
C3
+ 4ESR
+ R
+ R
2
3
4
1
. However, be careful about ESR. This
x C1) +1/(f
C
C
C
V –
x C1) +1/(f
SW2
1
2
2
SW2
–
+
–
OUT
TC682
C1
+ ESR
+ ESR
Inverting Voltage Doubler
+ 4ESR
GND
PUMP
C
V
PUMP
1
IN
+
C1
C1
7
6
5
+ R
+ R
x C2)
C2
x C2)
+ ESR
SW3
SW3
+
22 μF
C
+ R
+ R
OUT
3
IN
C3
SW4
= +5V and 3.3
SW4
for various
+ ESR
+ ESR
V –
SW
V
GND
IN
OUT
C2
) is
C2
)
)
Output voltage ripple is affected by C3. Typically the
larger the value of C3 the less the ripple for a given load
current. The formula for
V
For a 10 μF (0.5Ω ESR) capacitor for C3, f
kHz and I
at the output will be less then 60 mV. In most
applications (I
1-5 μF pump capacitors will suffice. Table 4-2 shows
V
TABLE 4-1:
TABLE 4-2:
RIPPLE
RIPPLE
C1, C2 (μF)
for different values of C3 (assume 1Ω ESR).
= {1/[2(f
OUT
C3 (μF)
100.00
100.00
10.00
22.00
10.00
22.00
0.05
0.10
0.47
1.00
3.30
5.00
0.50
1.00
3.30
5.00
OUT
= 10 mA the peak-to-peak ripple voltage
PUMP
< = 10 mA) a 10-20 μF capacitor and
OUTPUT RESISTANCE
VS. C1, C2
V
VS. C3 (I
RIPPLE
x C3)] + 2(ESR
P-P
PEAK-TO-PEAK
V
OUT
RIPPLE
10mA)
V
RIPPLE
is given below:
R
C3
DS21453C-page 5
TC682
OUT
4085
2084
1020
510
285
145
125
105
520
172
120
94
87
70
43
25
)} (I
(Ω)
(mV)
OUT
PUMP
)
= 10