© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE MULTI-MODE
DC-DC CONVERTER
SC1630
January 30, 1998
Note:
(1) Add suffix ‘TR’ for tape and reel.
FEATURES
• Default +5V output voltage
• Adjustable output voltage with two resistors
• Power-saving shutdown mode (7µA typical)
• 120kHz switching rate
• On-chip low battery detector
DESCRIPTION
The SC1630 is a DC-DC converter designed to drive
an external power switch for more flexibility, especially
in higher voltage and larger power applications.
Typically six components are required to set up a
step-up configuration easily achieving an efficiency
beyond 80%. A few more components are required to
set up a step down configuration delivering 4A load
current with 83% typical efficiency, 86% at 2A load,
and 300µA quiescent current.
The output voltage can be internally set to 5V or
externally set to an arbitrary value below breakdown
voltage of the power switch. Logic-controlled
shutdown mode is provided for power-saving. The low
battery detector can also be configured as a linear
regulator.
A 120kHz switching rate reduces the inductor size.
Inductors of 25µH to 50µH inductance are
recommended for most applications.
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
BLOCK DIAGRAM
APPLICATIONS
• Palmtop and notebook computers
• Battery charger supply
• Cellular telephones
• LCD contrast supply
• Flash memory programmer
• Battery backup supplies
• Portable instruments
ABSOLUTE MAXIMUM RATINGS
Parameter Symbol Maximum Units
Supply Voltage V
IN
7.0 V
Operating
Temperature Range
T
A
0 to 70 °C
Storage Temperature
Range
T
STG
-65 to 125 °C
PIN CONFIGURATION
DEVICE
(1)
PACKAGE
SC1630CS SO-8
ORDERING INFORMATION
© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE MULTI-MODE
DC-DC CONVERTER
SC1630
January 30, 1998
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, TA = 25°C, VIN = 3.0V
Parameter Conditions Min Typ Max Units
Input Voltage 1.8 7.0 V
Default Output Voltage I
L
= 200mA 4.80 5.00 5.20 V
Switch Off Current 105 140 µA
Shutdown Mode Current 7 15 µA
Recovery Time from Shutdown V
IN
= 2.5V,IL = 200mA 0.4 ms
Efficiency I
L
= 300mA (5V Output Step-Up
Converter)
85 %
Line Regulation V
IN
= 2.2 - 3.3V
V
OUT
= 5V, IL = 100mA
0.6 %V
OUT
Load Regulation IL = 10mA - 500mA
V
OUT
= 5V
2.5 %V
OUT
Oscillator Frequency 90 120 150 kHz
LBI Pin Trip Point 1.22 V
EXT Pin Driving Capabilities Pin 8 = 5V, Pin 3 = 0.85V
Sourcing
Sinking
80
50
mA
mA
LBO “ON Resistance” V
IN
= 2V 45
Ω
Input Pin Bias Current 10 nA/Pin
Output Pin Leakage 10 nA/Pin
TYPICAL APPLICATIONS
© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE MULTI-MODE
DC-DC CONVERTER
SC1630
January 30, 1998
TYPICAL APPLICATIONS (cont.)
5V Output Step-Up Converter
12V Output Step-Up Converter for Flash Memory
36V Output Step-Up Converter for Color LCD
© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE MULTI-MODE
DC-DC CONVERTER
SC1630
January 30, 1998
TYPICAL APPLICATIONS (cont.)
-24V Output Inverting Converter for LCD
2V Input 20mA Load -24V Output Inverting Converter for LCD
±12V Dual Output Converter for Computer Interfacing
© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE MULTI-MODE
DC-DC CONVERTER
SC1630
January 30, 1998
TYPICAL APPLICATIONS (cont.)
5V Output Step-Down Converter - 1
5V Output Step-Down Converter - 2
© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE MULTI-MODE
DC-DC CONVERTER
SC1630
January 30, 1998
TYPICAL APPLICATIONS (cont.)
TYPICAL PERFORMANCE CHARACTERISTICS
Step-Up Rechargeable Battery Charger
Step-Up/Step-Down Rechargeable Battery Charger
• Charging current =0.8A, Auto Cut-Off at 0.25% -Delta-V point and fault conditions (RIF sets the charging current).
• VDD must be lower than VBAT.
• Short circuit condition is protected with a 2A fuse.
• Fast charge current =0.8A when VDD<VBAT, = (VDD-VBAT-0.5)/0.82 when VDD>VBAT.
• Trickle charge current = 30mA (RIF sets fast charge current, RIT sets trickle charge current).
• Typical efficiency = 75%.
• With short circuit protection.
© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE MULTI-MODE
DC-DC CONVERTER
SC1630
January 30, 1998
TYPICAL PERFORMANCE CHARACTERISTICS (cont.)
© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE MULTI-MODE
DC-DC CONVERTER
SC1630
January 30, 1998
DEVICE OUTLINE - SO-8
PIN DESCRIPTIONS
PIN 1: SD The SC1630 goes into shutdown
mode and consumes less than 10µA
when the SD pin is pulled to ground,
and it goes into normal operating
mode when the SD pin is pulled to a
positive voltage above 100mV.
PIN 2: V
IN
Input supply.
PIN 3: EXT Push-Pull driver output to drive exter-
nal power switch.
PIN 4: GND Ground.
PIN 5: FB The output voltage can either be inter-
nally set to 5 volts by grounding the FB
pin, or it can be externally set to an
arbitrary voltage by applying to the FB
pin the divider voltage of two external
divider resistors. V
OUT
voltage is given
by the following equation:
Where: R1= Resistor connected beween FB
Pin and V
OUT
pin.
R2= Resistor connected between FB
Pin and ground.
V
OUT
= Output voltage to be set.
PIN 6: LBO Open drain output of the battery low
detector, with 45 Ohm “On Resis
tance” at V
IN
=2V. It is pulled low when
the voltage on LBI pin is below 1.22
volts.
PIN 7: LBI The inverting input of the battery low
detector, of which the non-inverting input is internally connected to the 1.22V
voltage reference.
PIN 8: V
OUT
The output voltage feeds back to the
IC through this pin for internally set 5V
operation. If the output voltage is
externally set, the V
OUT
pin can be tied
to any low impedance node with voltage between the external power
switch threshold and 7 volts.
+=
2
1
OUT
R
R
1611.0V
PIN CONFIGURATION
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