NSC LM2685MTCX, LM2685MTC Datasheet
LM2685
Dual Output Regulated Switched Capacitor Voltage
Converter
LM2685 Dual Output Regulated Switched Capacitor Voltage Converter
May 2000
General Description
The LM2685 CMOS charge-pump voltage converter operates as an input voltage doubler, +5V regulator and inverter
for aninput voltage in the range of +2.85V to +6.5V. Five low
cost capacitors are used in this circuit to provide up to 50mA
of output current at +5V (
LM2685 operates at a 130 kHz switching frequency to reduce output resistance and voltage ripple. With an operating
current of only 800µA (operating efficiency greater than 80%
with most loads) and 6µA typical shutdown current, the
LM2685 is ideal for use in battery powered systems. The device is in a small 14-pin TSSOP package.
±
5%), and 15mA at −5V. The
Features
n +5V regulated output
n Inverts V
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
(+5V) to V
05
NEG
(−5V)
DS101100-2
14-Pin TSSOP
DS101100-1
Ordering Information
Order Number Package Type
LM2685MTC TSSOP-14 MTC14 94 Units, Rail
LM2685MTCX TSSOP-14 MTC14 2.5k Units, Tape and Reel
© 2000 National Semiconductor Corporation DS101100 www.national.com
NSC Package
Drawing
Supplied As
Pin Description
LM2685
Pin No. Name Function
1V
IN
2 GND Power supply ground.
3V
4V
NEG
NSW
5 CE Chip enable input. This pin is high for normal operation and low for shutdown. (See
6 SDP Positive side shutdown input. This pin is low for normal operation and high for positive
7 SDN Negative side shutdown input. This pin is low for normal operation and high for negative
8C
9C
10 V
11 V
12 V
13 C
14 C
−
2
+
2
05
PSW
DBL
+
1
−
1
Power supply input voltage.
Negative output voltage created by inverting V05.
V
output connected through a series switch, NSW.
NEG
Shutdown and Load Disconnect section in the Detailed Device Description division).
side shutdown and V
load disconnect. (See Shutdown and Load Disconnect section
PSW
in the Detailed Device Description division).
side shutdown and V
load disconnect. (See Shutdown and Load Disconnect section
NSW
in the Detailed Device Description division).
The negative terminal of inverting charge-pump capacitor, C2.
The positive terminal of inverting charge-pump capacitor, C2.
Regulated +5V output.
V05output connected through a series switch, PSW.
Voltage Doubler Output. (2.85V ≤ VIN≤ 5.4V. See Voltage Doubler section).
The positive terminal of doubling charge-pump capacitor, C1.
The negative terminal of doubling charge-pump capacitor, C1.
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LM2685
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
GND to V
NEG
SDN, SDP, CE (GND − 0.3V) to
V
Continuous Output Current 80mA
05
V
Short-Circuit Duration to GND
05
to GND or
IN
) 6.8V
(V
+ 0.3V)
IN
Continuous Power Dissipation (T
A
= 25˚C) (Note 3) 600mW
T
(Note 3) 150˚C
JMAX
θ
(Note 3) 140˚C/W
JA
Operating Ambient Temp. Range −40˚C to 85˚C
Operating Junction Temp. Range −40˚C to 125˚C
Storage Temp. Range −65˚C to 150˚C
Lead Temp. (Soldering, 10 sec.) 300˚C
ESD Rating (Note 4) 2kV
(Note 2) Indefinite
Electrical Characteristics
Limits with standard typeface apply for TJ= 25˚C, and limits in boldface type apply over the full temperature range. Unless
otherwise specified V
Symbol Parameter Conditions Min Typ Max Units
+
V
I
Q
I
SD
V
SD
Supply Voltage 2.85 6.5 V
Supply Current No Load 800 1600
Shutdown Supply Current VIN= 6.5V 6 30 µA
Shutdown Pin Input Voltage for
CE, SDP, SDN
I
(+5V) Output Current at V
L
R
(−5V) Output Resistance at V
O
F
SW
P
EFF
V
05
G
LINE
G
LOAD
R
SW
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: V
85˚C, V
Note 3: The maximum allowable power dissipation is calculated by using P
ambient temperature and θ
Note 4: The human body model is a 100 pF capacitor discharged through a 1.5kΩ resistor into each pin.
Note 5: In the typical operating circuit, capacitors C
reduce output voltage and efficiency.
Note 6: Specified output resistance includes internal switch resistance and ESR of capacitors. See the Detailed Device Description section.
Note 7: The 50 mA maximum current assumes no current is drawn from V
Switch Frequency 85 130 180 kHz
Average Power Efficiency at V
Output Regulation 1mA<I
Line Regulation 2.85V<V
Load Regulation 1mA<I
Series Switch Resistance V
V
NSW
V
05
may be shorted to GND without damage. However, shorting V
05
must not be shorted to GND or device may be damaged.
05
= 3.6V, C1=C2=C3=C5= 2.2µF. C4= 4.7µF (Note 5)
IN
No Load, V
= 6.5V 300 600
IN
Logic Input High@6.5V 2.4
Logic Input Low
05
NEG
2.85V<V
IL= 15mA (Note 6) 20 40 Ω
2.85V ≤ VIN≤ 6.5V
05
= 25mA to GND
I
L
<
6.5V 50 mA
IN
<
50mA, VIN= 6.5V
L
(Note 7)
<
1mA
<
I
50mA, VIN= 6.5V
L
(Note 7)
<
3.6V 0.25
IN
<
<
V
3.6V
to
NEG
to V
PSW
is the junction-to-ambient thermal resistance of the specified package.
JA
and C2are 2.2µF,0.3ΩmaximumESR capacitors. Capacitors with higher ESR will increase output resistance,
1
>
V
IN
6.5V 0.05
IN
<
50mA, VIN= 6.5V 0.3 1.0 %
L
2.85V 1.5
to V05may damage the device and must be avoided. Also, for temperature above
NEG
=(T
DMAX
pin. See Voltage Doubler section in the Detailed Device Description.
DBL
@
6.5V 0.8
82 %
4.848 5.05 5.252
4.797 5.05 5.303
5.0
JMAX—TA
)/θJA, where T
is the maximum junction temperature, TAis the
JMAX
µA
V
V
%/V
Ω
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