TC1240AECHTR Microchip Technology, TC1240AECHTR Datasheet - Page 7

• Manufacturer Part Number: TC1240AECHTR
• Description: IC CHARGE PUMP CONV SOT23A-6
• Manufacturer: Microchip Technology
• Type: Switched Capacitor (Charge Pump), Doublerr

Specifications of TC1240AECHTR

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: -1.8 ~ -5.5 V, ±3.6 ~ ±11 V
• Current - Output: 20mA
• Frequency - Switching: 80kHz
• Voltage - Input: 2.5 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Power - Output: 600mW
• Primary Input Voltage: 5.5V
• No. Of Outputs: 1
• Output Current: 20mA
• Voltage Regulator Case Style: SOT-23A
• No. Of Pins: 6
• Operating Temperature Range: -40°C To +85°C
• Svhc: No SVHC (15-Dec-2010)
• Function: Step Up
• Output Voltage: 5 V to 11 V
• Maximum Operating Temperature: 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

4.0
The TC1240/TC1240A charge pump converter dou-
bles the voltage applied to the V
sists of a two-phase operation (Figure 4-1). During the
first phase, switches S
are closed. During this time, C
on V
second phase, S
are open.
During this second phase, C
V
C
needed. The actual voltage is slightly lower than 2 x V
since the four switches (S
and the load drains charge from reservoir capacitor C
FIGURE 4-1:
Charge Pump Doubler.
 2003 Microchip Technology Inc.
IN
2
, allowing energy to be delivered to the output as
volts. This connects C
IN
V
OSC
IN
and load current is supplied from C
DETAILED DESCRIPTION
S
S
3
1
2
and S
C1
2
Ideal Switched Capacitor
and S
4
S
S
1
4
are closed, while S
1
-S
2
1
to the reservoir capacitor
4
is level-shifted upward by
4
1
) have an on-resistance
V
are open and S
IN
charges to the voltage
IN
TC1240/TC1240A
pin. Conversion con-
C
2
V
OUT
2
. During the
= 2 x V
1
1
and S
and S
IN
IN
2
3
3
.
5.0
5.1
The TC1240/TC1240A performs voltage doubling but
does not provide regulation. The output voltage will
droop in a linear manner with respect to load current.
The value of this equivalent output resistance is approx-
imately 12Ω nominal at +25°C and V
TC1240A and 17Ω nominal at +25°C and V
for the TC1240. V
loads for the TC1240A and +5.6V for the TC1240, and
droops according to the equation below:
EQUATION
5.2
The overall power efficiency of the charge pump is
affected by four factors:
1.
2.
3.
4.
Most of the conversion losses are due to factors (2) and
(3) above. These losses are given by Equation 5-1.
EQUATION 5-1:
a)
b)
P
R
Losses from power consumed by the internal
oscillator, switch drive, etc. (which vary with
input
frequency).
I
MOSFET switches on-board the charge pump.
Charge pump capacitor losses due to effective
series resistance (ESR).
Losses that occur during charge transfer (from
commutation capacitor to the output capacitor)
when a voltage difference between the two
capacitors exist.
LOSS(2,3)
O UT
2
R losses due to the on-resistance of the
TYPICAL APPLICATIONS
Output Voltage Considerations
Charge Pump Efficiency
TC1240/TC1240A
=
V OUT
V DROOP
voltage,
--------------------- -
F
=
SW
I
1
OU T
(
2
C
OUT
=
1
)
2
×
temperature
×
is approximately +10.0V at light
=
+
R
V IN V DROOP
O UT
8R
I OUT
SWITCH
–
×
R OUT
+
4ESR
IN
and
DS21516C-page 7
= +5.0V for the
C1
oscillator
IN
+
= +2.8V
ESR
C2