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CAT32
CMOS White LED Driver
FEATURES
s Low quiescent ground current (0.5mA typical)
www.datasheet4u.com
s Power efficiency over 80%
s Compatible pinout with LT1932
s Adjustable output current (up to 40mA)
s High frequency 1.2MHz operation
s Input voltage operation down to 2.0V
s Low resistance (0.5) high voltage
power switch
APPLICATIONS
s Color LCD and keypad backlighting
s Cellular phones
s Handheld terminals
DESCRIPTION
The CAT32 is a DC/DC step up converter that delivers
a regulated output current. Operation at a constant
switching frequency of 1.2MHz allows the device to be
used with very small value external inductor and ceramic
capacitors.
The CAT32 is targeted to drive multiple white light-
emitting diodes (LEDs) connected in series and provides
the necessary regulated current to control the brightness
and the color purity. An external resistor RSET controls
the output current level. LED currents of up to 40mA
can be supported over a wide range of input supply
voltages from 2V to 7V, making the device ideal for
battery-powered applications.
TYPICAL APPLICATION
VIN
2.7V to 4.2V
ALOGEN FR
LEA D F REETM
s Drives up to 4 White LEDs in series
s Shutdown current less than 1µA
s Load fault protection against open-circuits
s Low value external components
s Low profile (1mm) 6-lead SOT23 and TDFN
(0.8mm) package
s Digital cameras
s PDAs/Games
s Portable MP3 players
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 power-down mode with “near zero” quiescent current.
In addition to overcurrent limiting protection, the device
also includes detection circuitry to ensure protection
against open-circuit load fault conditions.
The device is available in a low profile (1mm max height)
6-lead thin SOT23 package and in a TDFN (0.8mm max
height) package.
D1
61
VIN SW
PWM
DIMMING
CONTROL
CAT32
5 SHDN
LED 3
RSET
4
GND
2
15mA
SOT23 Pin Numbers
Figure 1. Li-Ion Driver for Four High-Brightness White LEDs
© 2004 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
C1: Taiyo Yuden JMK212BJ475
C2: Taiyo Yuden EMK212BJ105
D1: Zetez ZHCS400
L1: Sumida CLQ4D106R8
(Panasonic ELJEA6R8)
Doc No. 5001, Rev. AC

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CAT32
ORDERING INFORMATION
Part Number
CAT32EKT-TE7
www.daCtasAhTee3t24uR.cDo4m-TE7
CAT32RD4
CAT32TDI-TE7
Package
6-lead, thin SOT23
8-pad TDFN (3x3mm)
8-pad TDFN (3x3mm)
6-lead thin SOT23,
Lead Free
Tube
Quantity
120
Reel
Quantity
3000
3500
Package
Marking Code
BD
CCEM
CCEM
3000
LL
PIN CONFIGURATION
SW 1
GND 2
LED 3
CAT32
6 VIN
5 SHDN
4 RSET
Power
GROUND
1
VIN 2
SHDN 3
RSET 4
8 SW
7 NC
6 LED
5 GND
6-Lead SOT-23
1mm maximum height
θ
[Free Air]
PIN DESCRIPTIONS
Pin Number
Pin Number
SOT23
TDFN
18
25
36
44
53
62
1
(Top View)
TDFN Package: 3mm x 3mm
0.8mm maximum height
(RD4)
Name
SW
GND
LED
RSET
SHDN
VIN
Power
Ground
Function
Switch pin. This is the drain of the internal power
switch. For minimum EMI, minimize the trace
area connected to this pin.
Ground pin. Connect pin 2 to ground.
LED (cathode) connection pin.
RESET pin. A resistor connected from pin 4 to
ground sets the LED current. This pin is also
used to dim the LEDs.
Shutdown pin.
Input supply pin. This pin should be bypassed
with a capacitor to ground. A 4.7µF capacitor
mounted close to the pin is recommended.
Power Ground
Doc. No. 5001, Rev. AC
2

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CAT32
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for
prolonged time periods may affect device reliability. All voltages are with respect to ground.
VIN , LED, SHDN Voltage ....................................... 8V
SW Voltage ........................................................... 20V
RSET Voltage ......................................................... 1V
www.datasheet4u.com
Junction Temperature ....................................... 125°C
Lead Soldering Temperature (10 secs) ............ 300°C
Storage Temperature .......................... -65°C to 150°C
ESD Rating - Human Body Model .................... 2000V
RECOMMENDED OPERATING CONDITIONS
Parameter
Range
VIN
Ambient Temperature Range
2 to 7
-40 to +85
Inductor L1
6.8 ±20% typical
Input Capacitor C1
4.7 ±20% typical
Output Capacitor C2
1.0 ±20% typical
I with 1 to 4 LEDs in series
LED
0 to 20
Unit
V
°C
µH
µF
µF
mA
ELECTRICAL SPECIFICATIONS
Over recommended operating conditions unless otherwise specified. TA = 25°C, VIN = 2V and VSHDN = 1.2V.
Symbol
IQ
IGND
VLED
ILED
Parameter
Quiescent Current
Ground Current in Shutdown
LED Pin Voltage
LED Current Adjust Range
I Programmed LED Current
LED
ILED
VRSET
LED Pin Current Temperature Coefficient
RSET Pin Voltage
Shutdown Pin Logic High Level
Conditions
VRSET = 0.2V
VSHDN = 0V
VIN < VOUT, ILED =15mA
RSET = 562
RSET = 750
RSET = 1.5k
RSET = 4.53k
ILED = 15mA
RSET = 1.5k
Min
5
33
25
12.5
0.85
Typ
0.5
0.05
120
38
30
15
5
-0.01
100
Max
0.7
1
180
40
45
36
17.5
Units
mA
µA
mV
mA
mA
mA/° C
mV
V
Shutdown Pin Logic Low Level
0.25
V
fSW Boost Converter Frequency
0.8 1.2 1.6 MHz
ISWL Switch Current Limit
400 550 780 mA
VIN = 2V, ISW = 100mA
0.7 1.2
RSW
Switch Resistance
VIN = 3V, ISW = 100mA
0.5 0.9
Switch Leakage Current
Switch Off, VSW = 5V
0.01
5
µA
Efficiency
Components shown
on Figure 1
83
%
3 Doc No. 5001, Rev. AC