LOW VOLTAGE STEP-UP
DC-DC CONVERTER
January 29, 1998
SC1633
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DESCRIPTION
The SC1633 is a high efficiency step up DC-DC
converter. Only four external components are required
to deliver a fixed voltage of 3V, 3.3V, or 5V. Efficiency
beyond 83% can be easily achieved at 70mA load with
2.2V to 3V input voltages.
A logic-controlled shutdown mode is provided for
power saving. Switch current limit can be programmed
with a resistor. The low battery detector can be
configured as a linear regulator or a burst mode
controller providing extremely low supply current
operation.
A switching rate of 120kHz reduces the inductor size -
inductors of 47µH to 150µH inductance are
recommended for most applications.
FEATURES
•
High efficiency 87%
•
Power-saving shutdown mode (7µA typical)
•
Internal 0.8A switch
•
120kHz switching rate
•
Adjustable switch current limit
•
On-chip low battery detector
APPLICATIONS
•
Pocket organizers
•
Electronic dictionaries
•
Cameras
•
Pagers
•
Bar code scanners
•
LCD displays
•
Battery backup supplies
•
Portable instruments
ORDERING INFORMATION
BLOCK DIAGRAM
DEVICE
(1)
VOLTAGE
3.3V
3.0V
5.0V
PACKAGE
SO-8
SC1633CS
SC1633-3CS
SC1633-5CS
Note:
(1) Add suffix ‘TR’ for tape and reel.
ABSOLUTE MAXIMUM RATINGS
Parameter
Supply Voltage
Operating
Temperature Range
Storage
Temperature Range
Symbol
V
IN
T
A
T
STG
Maximum
7.0
0 to 70
-65 to 125
Units
V
°C
°C
PIN CONFIGURATION
TYPICAL APPLICATION CIRCUIT
© 1997 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE STEP-UP
DC-DC CONVERTER
January 29, 1998
SC1633
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, T
A
= 25°C, V
IN
= 3.0V
Parameter
Input Voltage
Output Voltage
SC1633
SC1633-3
SC1633-5
Switch Off Current
No Load Current
SC1633/SC1633-3
SC1633-5
Shutdown Mode Current
Shutdown Recovery Time
Efficiency
SC1633/SC1633-3
SC1633-5
Line Regulation
SC1633
SC1633-3
SC1633-5
Load Regulation
SC1633/SC1633-3
SC1633-5
Oscillator Frequency
LBI Pin Trip Point
LBO “On Resistance”
SW “On Resistance”
SC1633/SC1633-3
SC1633-5
SW Off Leakage
Input Pin Bias Current
Output Pin Leakage
V
IN
= 2V
V
IN
=2.0 - 3.3V
V
IN
=2.0 - 3.0V
V
IN
=2.2 - 4.5V
V
IN
=2.5V
I
L
=70mA
I
L
=70mA
I
L
= 70mA
V
IN
I
L
Min
1.8
3.16
2.88
4.80
3.30
3.00
5.00
105
160
250
7
1.8
87
86
0.6
0.6
0.5
0.6
0.5
90
1.17
120
1.22
45
1.75
1.25
1
10
10
150
1.27
15
Typ
Max
7.0
3.44
3.12
5.20
140
Units
V
V
µA
µA
µA
msec
%
I
L
=40mA
%V
OUT
I
L
=1mA - 70mA
%V
OUT
kHz
V
Ω
Ω
µA
nA/Pin
nA/Pin
© 1997 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE STEP-UP
DC-DC CONVERTER
January 29, 1998
SC1633
TYPICAL PERFORMANCE CHARACTERISTICS (cont.)
APPLICATION EXAMPLES
Figure 1. 3V Output Step-Up Converter
© 1997 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE STEP-UP
DC-DC CONVERTER
January 29, 1998
SC1633
APPLICATION EXAMPLES (cont.)
Figure 2. 5V Output Step-Up Converter
Figure 3. 1-Cell Input 3V Output Step-Up Converter
Figure 4. 4-Cell Input Step-Up/Step-Down Converter
© 1997 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
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