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LED Driver. CAT37 Datasheet

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LED Driver. CAT37 Datasheet
















CAT37 Driver. Datasheet pdf. Equivalent













Part

CAT37

Description

CMOS White LED Driver



Feature


CAT37 CMOS White LED Driver Boost Conve rter Description The CAT37 is a DC/DC s tep up converter that delivers a regula ted output current. Operation at a cons tant switching frequency of 1.2 MHz all ows the device to be used with very sma ll value external inductor and ceramic capacitors. The CAT37 is targeted to dr ive multiple white light−emitting dio des (LEDs) connected.
Manufacture

ON Semiconductor

Datasheet
Download CAT37 Datasheet


ON Semiconductor CAT37

CAT37; in series and provides the necessary re gulated current to control the brightne ss and the color purity. An external re sistor R1 controls the output current l evel. LED currents of up to 40 mA can b e supported over a wide range of input supply voltages from 2.5 V to 7 V, maki ng the device ideal for battery−power ed applications. A high voltage output stage allows up to 4.


ON Semiconductor CAT37

White LEDs to be driven in series. Seri es drive provides inherent current matc hing. LED dimming can be done by using a DC voltage, a logic signal, or a puls e width modulation (PWM) signal. The sh utdown input pin allows the device to b e placed in power−down mode with “n ear zero” quiescent current. In addit ion to overcurrent limiting protection, the device also include.


ON Semiconductor CAT37

s detection circuitry to ensure protecti on against open−circuit load fault co nditions. The device is available in a low profile (1 mm max height) 5−lead TSOT−23 package. Features • Low Qui escent Ground Current (0.5 mA Typical) • Power Efficiency Over 80% • Compa tible Pinout with LT1937 • Adjustable Output Current (up to 40 mA) • High Frequency 1.2 MHz Operation • Inpu.





Part

CAT37

Description

CMOS White LED Driver



Feature


CAT37 CMOS White LED Driver Boost Conve rter Description The CAT37 is a DC/DC s tep up converter that delivers a regula ted output current. Operation at a cons tant switching frequency of 1.2 MHz all ows the device to be used with very sma ll value external inductor and ceramic capacitors. The CAT37 is targeted to dr ive multiple white light−emitting dio des (LEDs) connected.
Manufacture

ON Semiconductor

Datasheet
Download CAT37 Datasheet




 CAT37
CAT37
CMOS White LED Driver
Boost Converter
Description
The CAT37 is a DC/DC step up converter that delivers a regulated
output current. Operation at a constant switching frequency of
1.2 MHz allows the device to be used with very small value external
inductor and ceramic capacitors.
The CAT37 is targeted to drive multiple white lightemitting diodes
(LEDs) connected in series and provides the necessary regulated current
to control the brightness and the color purity. An external resistor R1
controls the output current level. LED currents of up to 40 mA can be
supported over a wide range of input supply voltages from 2.5 V to 7 V,
making the device ideal for batterypowered applications.
A high voltage output stage allows up to 4 White LEDs to be driven
in series. Series drive provides inherent current matching.
LED dimming can be done by using a DC voltage, a logic signal, or
a pulse width modulation (PWM) signal. The shutdown input pin
allows the device to be placed in powerdown mode with “near zero”
quiescent current.
In addition to overcurrent limiting protection, the device also
includes detection circuitry to ensure protection against opencircuit
load fault conditions.
The device is available in a low profile (1 mm max height) 5lead
TSOT23 package.
Features
Low Quiescent Ground Current (0.5 mA Typical)
Power Efficiency Over 80%
Compatible Pinout with LT1937
Adjustable Output Current (up to 40 mA)
High Frequency 1.2 MHz Operation
Input Voltage Operation down to 2.5 V
Low Resistance (0.5 W) Power Switch
Drives up to 4 White LEDs in Series
Shutdown Current Less than 1 mA
Load Fault Protection Against Opencircuits
Low Value External Components
Low Profile (1 mm) TSOT23 5lead Package
These Devices are PbFree, Halogen Free/BFR Free and are RoHS
Compliant
Applications
Color LCD and Keypad Backlighting
Cellular Phones
Handheld Terminals
Digital Cameras
PDAs/Games
Portable MP3 Players
© Semiconductor Components Industries, LLC, 2010
1
February, 2010 Rev. 21
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5
1
TSOT23
TD SUFFIX
CASE 419AE
PIN CONNECTIONS
1
SW
VIN
GND
FB
SHDN
(Top View)
1 mm Maximum Height
qJA = 250°C/W (free air)
MARKING DIAGRAM
LMYM
ULYM
LM = CAT37TDIT3
UL = CAT37TDIGT3
Y = Production Year (Last Digit)
M = Production Month (19, A, B, C)
ORDERING INFORMATION
Device
CAT37TDIT3
(Note 1)
Package
TSOT23
(PbFree)
Shipping
3,000/
Tape & Reel
CAT37TDIGT3
(Note 2)
TSOT23
3,000/
(PbFree) Tape & Reel
1. MatteTin Plated Finish (RoHScompliant).
2. NiPdAu Plated Finish (RoHScompliant).
Publication Order Number:
CAT37/D




 CAT37
CAT37
Typical Application Circuit
VIN
3 V to 5 V
L1 6.8 mH D1
C1
1 mF
5
1
VIN
SW
ON OFF
CAT37
4
SHDN
GND
2
3
FB
C2
1 mF
15 mA
C1: Taiyo Yuden JMK212BJ475
C2: Taiyo Yuden EMK212BJ105
L1: Panasonic ELJEA6R8 or equivalent
R1
6.34 W
Figure 1. Driver for Four HighBrightness White LEDs
Table 1. PIN DESCRIPTION
Pin Number
Name
Function
1
SW
Switch pin. This is the drain of the internal power switch. For minimum EMI, minimize the trace area
connected to this pin.
2
GND
Ground pin. Connect pin 2 to ground.
3
FB
LED (cathode) connection pin.
4
SHDN Shutdown pin.
5
VIN
Input supply pin. This pin should be bypassed with a capacitor to ground. A 1 mF capacitor mounted
close to the pin is recommended.
Table 2. ABSOLUTE MAXIMUM RATINGS
Parameter
Rating
Unit
VIN, FB, SHDN voltage
SW voltage
8
V
20
V
Storage Temperature Range
65 to +160
°C
Junction Temperature
125
°C
Lead Soldering Temperature (10 secs)
300
°C
ESD Rating – Human Body Model
2000
V
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
Table 3. RECOMMENDED OPERATING CONDITIONS
Parameter
VIN
Ambient Temperature Range
Inductor L1
Input Capacitor C1
Output Capacitor C2
ILED with 1 to 4 LEDs in series
NOTE: Typical application circuit with external components is shown above.
Range
Unit
2.5 to 7
V
40 to +85
°C
6.8 ± 20% typical
mH
1.0 ± 20% typical
mF
1.0 ± 20% typical
mF
0 to 20
mA
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2




 CAT37
CAT37
Table 4. ELECTRICAL OPERATING CHARACTERISTICS
(Over recommended operating conditions unless otherwise specified. TA = 25°C, VIN = 3 V and VSHDN = 3 V.)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
Input Voltage Range
2.5
7
V
IQ
Quiescent Current
ISD
Shutdown Current
VFB
FB Pin Voltage
IFB
FB Pin Leakage Current
Shutdown High Threshold
VFB = 0.2 V
VSHDN = 0 V
4 LEDs at 15 mA
0.5
0.7
mA
0.05
1
mA
85
95
105
mV
1
2
mA
0.85
V
Shutdown Low Threshold
0.25
V
ISHDN
fSW
DC
Shutdown Pin Current
Boost Converter Frequency
Maximum Switch Duty Cycle
1
nA
0.8
1.2
1.6
MHz
90
95
%
ISWL
Switch Current Limit
Switch Saturation Voltage
Switch Leakage Current
Efficiency
ISW = 300 mA
Switch Off, VSW = 5 V
Figure 1 with specified components
400
550
780
mA
150
200
mV
0.01
5
mA
83
%
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3




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