NSC LM3351MMX, LM3351MM Datasheet
LM3351
Switched Capacitor Voltage Converter
General Description
The LM3351 is a CMOS charge-pump voltage converter
which efficiently provides a 3.3V to 5V step-up, or 5V to 3.3V
step-down. The LM3351 is pin for pin compatible with the
LM3350 but consumes 66%less quiescent current. The
LM3351 uses four small, low cost capacitors to provide the
voltage conversion. It eliminates the cost, size and radiated
EMI related to inductor based circuits, or the power loss of a
linear regulator. Operating power conversion efficiency
greater than 90%provides ideal performance for battery
powered portable systems.
The architecture provides a fixed voltage conversion ratio of
3/2 or 2/3. Thus it can be used for other DC-DC conversions
as well.
Key Specifications
n 200 kHz switch frequency allows use of very small,
inexpensive capacitors.
Ordering Information
n 4.2Ω typical step-up output impedance
n 1.8Ω typical step-down output impedance
n 95%typical power conversion efficiency at 50 mA
n 250 nA typical shutdown current
n Low quiescent current extends battary life
Features
n Conversion of 3.3V to 5V, or 5V to 3.3V
n Small Mini SO-8 package
n No inductor required
Applications
n Any mixed 5V and 3.3V system
n Laptop computers and PDAs
n Handheld instrumentation
n PCMCIA cards
LM3351 Switched Capacitor Voltage Converter
December 1999
Order Number Package Type
LM3351MMX Mini SO-8 MUA08A S05A 3500 Units on Tape and Reel
LM3351MM Mini SO-8 MUA08A S05A 1000 Units on Tape and Reel
NSC Package
Drawing
Package
Marking
Supplied As
Basic Operating Circuits
Step-Up Converter
DS100146-1
Step-Down Converter
Connection Diagram
Mini SO8 Package
DS100146-3
Top View
DS100146-2
© 1999 National Semiconductor Corporation DS100146 www.national.com
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
LM3351
please contact the National SemiconductorSalesOffice/
Distributors for availability and specifications.
Maximum Input Voltage, Step-Down 5.5V
Maximum Input Voltage, Step-Up 3.65V
Power Dissipation (P
(Note 2))
(Note 2) 250˚C/W
θ
ja
)(TA=25˚C,
D
500 mW
Storage Temperature −65˚C to +150˚C
Lead Temperature (Soldering, 10
secs)
ESD Susceptibility (Note 3) 2kV
Not short circuit protected.
Operating Conditions (Note 1)
Ambient Temperature Range −40˚C to + 85˚C
Tj Max (Note 2) 150˚C
Electrical Characteristics
3/2 Step-Up Voltage Converter
Specifications in standard type face are for Tj= 25˚C, and those with boldface type apply over full operating temperature
range. Unless otherwise specified, V
= 3.3V, V
in
Enable
= 3.3V, I
= 50 mA, C1,C2,Cinand C
load
Symbol Parameter Conditions Typ (Note 4) Limits (Note 5) Units
V
V
V
I
Q1
I
Q2
Z
f
SW
V
I
Enable
P
out
out
in
out
Enable
η
Output Voltage at
NL
No Load
Output Voltage at
FL
50 mA
Input Supply
Voltage Range
Quiescent Current Shutdown Mode, V
Quiescent Current Normal Mode, I
Output Source
Impedance
Switching
Frequency
Enable Threshold
Voltage
Leakage Current Current into ENABLE pin; ENABLE =
Power Efficiency 95
I
= 0 A 5.0 V
load
I
=50mA 4.7 V
load
3.3 V
= 0V,
=0 A; Current into pin V
I
load
pin V
Iow
I
=50mA 4.2 Ω
load
Enable
= 0A; Current into
Ioad
low
0.025 µA
1.1 mA
(Note 6) 200 kHz
1.7 V
0.025 µA
5V and all other pins at ground
=
1 µF.
out
2.5 V(Min)
3.65 V(Max)
3 µA(Max)
1.5 mA(Max)
6.25 Ω (Max)
125 kHz(Min)
275 kHz(Max)
1.0 V(Min)
2.5 V(Max)
1 µA(Max)
260˚C
%
Electrical Characteristics
2/3 Step-Down Voltage Converter
Specifications in standard type face are for Tj= 25˚C, and those with boldface type apply over full operating temperature
range. Unless otherwise specified, V
high
= 5V, V
Enable
= 5V, I
= 50 mA, C1,C2,Cinand C
load
Symbol Parameter Conditions Typ (Note 4) Limits (Note 5) Units
V
out
V
out
V
in
I
Q1
www.national.com 2
Output Voltage at
NL
No Load
Output Voltage at
FL
50 mA
Input Supply
Voltage Range
Quiescent Current Shutdown Mode, V
I
= 0 A 3.3 V
load
I
=50 mA 3.2 V
load
5V
=0 A; Current into pin V
I
load
Enable
= 0V,
high
0.25 µA
=
1 µF.
out
2.2 V(Min)
5.5 V(Max)
3 µA(Max)
Electrical Characteristics
2/3 Step-Down Voltage Converter
Specifications in standard type face are for Tj= 25˚C, and those with boldface type apply over full operating temperature
range. Unless otherwise specified, V
Symbol Parameter Conditions Typ (Note 4) Limits (Note 5) Units
I
Q2
Z
out
f
SW
V
Enable
I
Enable
P
η
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 befunctional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 2: For operation at elevated temperatures, LM3351 must be derated based on package thermal resistance of θ
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kW resistor into each pin.
Note 4: Typical numbers are at 25˚C and represent the most likely parametric norm.
Note 5: Limits are 100%production tested at 25˚C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control
(SQC) methods. The limits are used to calculate National’s Averaging Outgoing Quality Level (AOQL).
Note 6: The internal oscillator runs at 1.6 MHz, the output switches operate at one eighth of the oscillator frequency, f
Quiescent Current Normal Mode, I
Output Source
Impedance
Switching
Frequency
Enable Threshold
Voltage
Leakage Current Current into ENABLE pin; ENABLE =
Power Efficiency 95
= 5V, V
high
pin V
high
I
=50mA 1.8 Ω
load
(Note 6) 200 kHz
5V and all other pins at ground
(Continued)
= 5V, I
Enable
= 0A; Current into
Ioad
= 50 mA, C1,C2,Cinand C
load
0.8 mA
1.7 V
0.025 µA
=
1 µF.
out
1.0 mA(Max)
3 Ω(Max)
125 kHz(Min)
275 kHz(Max)
1.0 V(Min)
2.5 V(Max)
1 µA(Max)
and Tjmax, Tj=TA+θjaPD.
ja
=
.
8f
OSC
SW
%
LM3351
Typical Performance Characteristics
V
vs I
load
(Step-Up)
DS100146-4
out
Pηvs I
load
(Step-Up)
DS100146-5
Output Source Impedance vs
Temperature (Step-Up)
DS100146-6
www.national.com3
Loading...