LM2767
Switched Capacitor Voltage Converter
General Description
The LM2767 CMOS charge-pump voltage converter oper-
ates as a voltage doubler for an input voltage in the range of
+1.8V to +5.5V. Two low cost capacitors and a diode are
used in this circuit to provide at least 15 mA of output current.
The LM2767 operates at 11 kHz switching frequency to
avoid audio voice-band interference. With an operating cur-
rent of only 40 A (operating efficiency greater than 90% with
most loads), the LM2767 provides ideal performance for bat-
tery powered systems. The device is manufactured in a
SOT23-5 package.
Features
n
Doubles Input Supply Voltage
n
SOT23-5 Package
n
20
Typical Output Impedance
n
96% Typical Conversion Efficiency at 15mA
Applications
n
Cellular Phones
n
Pagers
n
PDAs, Organizers
n
Operational Amplifier Power Suppliers
n
Interface Power Suppliers
n
Handheld Instruments
Basic Application Circuit
Ordering Information
Order Number
Package
Number
Package
Marking
Supplied as
LM2767M5
MA05B
S17B (Note 1)
Tape and Reel (1000 units/reel)
LM2767M5X
MA05B
S17B (Note 1)
Tape and Reel (3000 units/reel)
Note 1: The small physical size of the SOT-23 package does not allow for the full part number marking. Devices will be marked with the designation shown in
the column Package Marking.
Voltage Doubler
DS101274-1
February 2000
LM2767
Switched
Capacitor
V
oltage
Converter
2000 National Semiconductor Corporation
DS101274
www.national.com
Absolute Maximum Ratings
(Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (V+ to GND, or V+ to V
OUT
)
5.8V
V
OUT
Continuous Output Current
30 mA
Output Short-Circuit Duration to GND (Note 3)
1 sec.
Continuous Power
Dissipation (T
A
= 25C)(Note 4)
400 mW
T
JMax
(Note 4)
150C
Operating Ratings
JA
(Note 4)
210C/W
Junction Temperature Range
-40C to 100C
Ambient Temperature Range
-40C to 85C
Storage Temperature Range
-65C to 150C
Lead Temp. (Soldering, 10 sec.)
240C
ESD Rating (Note 5)
Human Body Model
Machine Model
2kV
200V
Electrical Characteristics
Limits in standard typeface are for T
J
= 25C, and limits in boldface type apply over the full operating temperature range. Un-
less otherwise specified: V+ = 5V, C
1
= C
2
= 10 F. (Note 6)
Symbol
Parameter
Condition
Min
Typ
Max
Units
V+
Supply Voltage
1.8
5.5
V
I
Q
Supply Current
No Load
40
90
A
I
L
Output Current
1.8V
V+
5.5V
15
mA
R
OUT
Output Resistance (Note 7)
I
L
= 15 mA
20
40
f
OSC
Oscillator Frequency
(Note 8)
8
22
50
kHz
f
SW
Switching Frequency
(Note 8)
4
11
25
kHz
P
EFF
Power Efficiency
R
L
(5.0k) between GND and
OUT
98
%
I
L
= 15 mA to GND
96
V
OEFF
Voltage Conversion Efficiency
No Load
99.96
%
Note 2: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device
beyond its rated operating conditions.
Note 3: V
OUT
may be shorted to GND for one second without damage. For temperatures above 85C, V
OUT
must not be shorted to GND or device may be damaged.
Note 4: The maximum allowable power dissipation is calculated by using P
DMax
= (T
JMax
- T
A
)/
JA
, where T
JMax
is the maximum junction temperature, T
A
is the
ambient temperature, and
JA
is the junction-to-ambient thermal resistance of the specified package.
Note 5: The human body model is a 100pF capacitor discharged through a 1.5k
resistor into each pin. The machine model is a 200pF capacitor discharged directly
into each pin.
Note 6: In the test circuit, capacitors C
1
and C
2
are 10 F, 0.3
maximum ESR capacitors. Capacitors with higher ESR will increase output resistance, reduce output
voltage and efficiency.
Note 7: Specified output resistance includes internal switch resistance and capacitor ESR. See the details in the application information for positive voltage doubler.
Note 8: The output switches operate at one half of the oscillator frequency, f
OSC
= 2f
SW
.
LM2767
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3
Test Circuit
Typical Performance Characteristics
(Circuit of Figure 1, V
IN
= 5V, T
A
= 25C unless otherwise
specified)
DS101274-3
FIGURE 1. LM2767 Test Circuit
Supply Current vs
Supply Voltage
DS101274-4
Output Resistance vs
Capacitance
DS101274-5
Output Resistance vs
Supply Voltage
DS101274-6
Output Resistance vs
Temperature
DS101274-7
LM2767
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4
Typical Performance Characteristics
(Circuit of Figure 1, V
IN
= 5V, T
A
= 25C unless otherwise
specified) (Continued)
Output Voltage vs
Load Current
DS101274-8
Efficiency vs
Load Current
DS101274-9
Switching Frequency vs
Supply Voltage
DS101274-10
Switching Frequency vs
Temperature
DS101274-11
Output Ripple vs
Load Current
DS101274-23
LM2767
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5
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