LM2686
Regulated Switched Capacitor Voltage Converter
General Description
The LM2686 CMOS charge-pump voltage converter oper-
ates as an input voltage doubler and a +5V regulator for an
input voltage in the range of +2.85V to +6.5V. Three low cost
capacitors are used in this circuit to provide up to 50mA of
output current at +5.0V (
5%). The LM2686 operates at a
130 kHz switching frequency to reduce output resistance
and voltage ripple. With an operating current of only 450A
(operating efficiency greater than 80% with most loads) and
6.0A typical shutdown current, the LM2686 is ideal for use
in battery powered systems. The device is in a small 14-pin
TSSOP package.
Features
n
+5V regulated output
n
Doubles input supply voltage
n
TSSOP 14 package
n
80% typical conversion efficiency at 25mA
n
Input voltage range of 2.85V to 6.5V
n
Independent shutdown control pins
Applications
n
Cellular phones
n
Pagers
n
PDAs
n
Handheld Instrumentation
n
3.3V to 5V Voltage Conversion Applications
Typical Application and Connection Diagram
Ordering Information
Order Number
Package Type
NSC Package
Drawing
Supplied As
LM2686MTC
TSSOP-14
MTC14
94 Units, Rail
LM2686MTCX
TSSOP-14
MTC14
2.5k Units, Tape and Reel
DS101141-1
DS101141-2
14-Pin TSSOP
November 1999
LM2686
Regulated
Switched
Capacitor
V
oltage
Converter
1999 National Semiconductor Corporation
DS101141
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Pin Description
Pin No.
Name
Function
1
V
IN
*
Power supply input voltage.
2
GND
**
Power supply ground.
3
GND
**
Power supply ground.
4
GND
**
Power supply ground.
5
CE
Chip enable input. This pin is high for normal operation and low for shutdown and V
PSW
load disconnect.
6
SD
Shutdown input. This pin is low for normal operation and high for shutdown and V
PSW
load disconnect.
7
V
IN
*
Power supply input voltage.
8
NC
No connection.
9
NC
No connection.
10
V
05
Regulated +5V output.
11
V
PSW
V
05
output connected through a series switch, PSW.
12
V
DBL
Output of doubled input voltage.
13
C
1
+
The positive terminal of doubling charge-pump capacitor, C1.
14
C
1
-
The negative terminal of doubling charge-pump capacitor, C1.
*
All V
IN
pins, pin 1 and pin 7 must be tied together for proper operation.
**
All ground pins, pin 2, pin 3 and pin 4 must be tied together for proper operation.
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Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (V
IN
to GND)
6.8V
SD, CE
(GND - 0.3V) to
(V
In
+ 0.3V)
V
05
Continuous Output Current
80mA
V
05
Short-Circuit Duration to GND
(Note 2)
Indefinite
Continuous Power Dissipation (T
A
= 25C) (Note 3)
600mW
T
JMAX
(Note 3)
150C
JA
(Note 3)
140C/W
Operating Ambient Temp. Range
-40C to 85C
Operating Junction Temperature
Range
-40C to 125C
Storage Temp. Range
-65C to 150C
Lead Temp. (Soldering, 10 sec.)
300C
ESD Rating (Note 4)
2kV
Electrical Characteristics
Limits with standard typeface apply for T
J
= 25C, and limits in boldface type apply over the full temperature range. Unless
otherwise specified V
IN
= 3.6V, C
1
= C
3
= 2.2F. C
2
= 4.7F. (Note 5)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
V
+
Supply Voltage
2.85
6.5
V
I
Q
Supply Current
No Load
450
950
A
I
SD
Shutdown Supply Current
V
IN
= 6.5V
6
30
A
V
SD
Shutdown Pin Input Voltage for
CE, SD
Logic Input High
@
6.5V
2.4
V
Logic Input Low
@
6.5V
0.8
I
L
(+5V)
Output Current at V
05
2.85V
<
V
IN
<
6.5V
50
mA
F
SW
Switch Frequency
85
130
180
kHz
P
EFF
Average Power Efficiency at V
05
2.85V
<
V
IN
<
6.5V
I
L
= 25mA to GND
82
%
V
05
Output Regulation
1mA
<
I
L
<
50mA, V
IN
= 6.5V
(Note 6)
4.848
5.05
5.252
V
1mA
<
I
L
<
50mA, V
IN
= 6.5V
(Note 6)
4.797
5.05
5.303
V
G
LINE
Line Regulation
2.85V
<
V
IN
<
3.6V
0.25
%/V
3.6V
<
V
IN
<
6.5V
0.05
G
LOAD
Load Regulation
1mA
<
I
L
<
50mA, V
IN
= 6.5V
0.3
1.0
%
R
SW
Series Switch Resistance from
V
05
to V
PSW
V
IN
>
2.85V
5.0
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is in-
tended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: V
05
may be shorted to GND without damage. For temperature above 85C, V
05
must not be shorted to GND or device may be damaged.
Note 3: 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 4: The human body model is a 100pF capacitor discharged through a 1.5k
resistor into each pin.
Note 5: In the typical operating circuit, capacitors C
1
and C
3
are 2.2F, 0.3
maximum ESR capacitors. Capacitors with higher ESR will increase output resistance,
reduce output voltage and efficiency.
Note 6: The 50mA maximum current assumes no current is drawn from V
DBL
pin. See Voltage Doubler section in the Detailed Device Description.
LM2686
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Typical Performance Characteristics
Unless otherwise specified, T
A
= 25C, V
IN
= 3.6V.
Supply Current vs Input Voltage
DS101141-6
Supply Current vs Temperature
DS101141-7
Efficiency vs Load Current (V
IN
=
3.0V)
DS101141-8
Output Resistance (VDBL) vs.
Temperature (V
IN
= 3.6V)
DS101141-12
Switch Frequency vs. Temperature
(V
IN
= 3.6V)
DS101141-13
Line Transient Response (with 5mA
Load)
DS101141-14
A: INPUT VOLTAGE: V
IN
= 3.2V to 6.0V, 5V/div
B: OUTPUT VOLTAGE: V
PSW
: 100mV/div
V
05
Load Transient Response
DS101141-15
A: LOAD CURRENT: I
LOAD
= 5mA to 39.6mA,
10mA/div
B: OUTPUT VOLTAGE: V
05
: 10mV/div
V
PSW
Response to CE
(with 5mA Load)
DS101141-17
A: CE INPUT: 5V/div
B: OUTPUT VOLTAGE: V
PSW
: 5V/div
V
05
Response to SD (with 5mA
Load)
DS101141-18
A: SD INPUT: 5V/div
B: OUTPUT VOLTAGE: 5V/div
LM2686
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Typical Performance Characteristics
Unless otherwise specified, T
A
= 25C, V
IN
=
3.6V. (Continued)
Output Voltage (V
05
) vs. Load
Current
(V
IN
= 3.6V)
DS101141-9
Output Resistance (VDBL) vs. Input
Voltage
DS101141-11
V
05
Voltage vs. Input Voltage
DS101141-19
LM2686
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