CAT4139
© Catalyst Semiconductor, Inc. 1 Doc. No. MD-5032 Rev. A
Characteristics subject to change without notice
FEATURES
Switch Current Limit 750mA
Drives LED strings up to 22V
Up to 87% Efficiency
Low Quiescent Ground Current 0.6mA
1MHz Fixed Frequency Low noise Operation
Soft start “in-rush” current limiting
Shutdown current less than 1μA
Open LED Overvoltage Protection
Automatic Shutdown at 1.9V (UVLO)
Thermal overload protection
TSOT-23 5-Lead (1mm max height)
APPLICATIONS
GPS Navigation Systems
Portable Media Players
Handheld Devices
ORDERING INFORMATION
Part Number Package Quantity
per Reel
Package
Marking
CAT4139TD-GT3 TSOT23-5* 3000 TP
* NiPdAu Plated Finish, RoHS compliant
For Ordering Information details, see page 12.
DESCRIPTION
The CAT4139 is a DC/DC step-up converter that
delivers an accurate constant current ideal for driving
LEDs. Operation at a fixed switching frequency of
1MHz allows the device to be used with small value
external ceramic capacitors and inductor. LEDs
connected in series are driven with a regulated
current set by the external resistor R1. The CAT4139
is ideal for driving parallel strings of up to five white
LEDs in series or up to 22V.
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 “zero” quiescent
current.
In addition to thermal protection and overload current
limiting, the device also enters a very low power
operating mode during “Open LED” fault conditions.
The device is housed in a low profile (1mm max
height) 5-lead TSOT-23 package for space critical
applications.
PIN CONFIGURATION TYPICAL APPLICATION CIRCUIT
TSOT-23 5-Lead
Top View
VIN
CAT4139
VIN LD
VOUT
9 strings at
20mA
IOUT
R1
1.62Ω
R2 180mA
(300mV)
4.7µF
5V
C1
1µF
35V
C2
FBSHDN
SW
GND
ON
22µH
OFF
1kΩ
22V High Current Boost White LED Driver
L: Sumida CDRH6D28-220
D: Central CMSH1-40 (rated 40V)
VIN
FB
2
3
1
SHDN
5
4
SW
GND
CAT4139
Doc. No. MD-5032 Rev. A 2 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
ABSOLUTE MAXIMUM RATINGS
Parameters Ratings Units
VIN, FB Voltage -0.3 to +7 V
SHDN
¯¯¯¯¯ Voltage -0.3 to +7 V
SW Voltage -0.3 to 40 V
Storage Temperature Range -65 to +160 ºC
Junction Temperature Range -40 to +150 ºC
Lead Temperature 300 ºC
RECOMMENDED OPERATING CONDITIONS
Typical application circuit with external components are shown on page 1.
Parameters Range Units
VIN up to 5.5 V
SW pin voltage 0 to 22 V
Ambient Temperature Range(1) -40 to +85 ºC
DC ELECTRICAL CHARACTERISTICS
VIN = 3.6V, ambient temperature of 25ºC (over recommended operating conditions unless specified otherwise).
Symbol Parameter Test Conditions Min Typ Max Units
IQ Operating Current VFB = 0.2V
VFB = 0.4V (not switching) 0.6
0.1
1.5
0.6 mA
ISD Shutdown Current VSHDN
¯¯¯¯¯ = 0V 0.1 1 µA
VFB FB Pin Voltage 9 x 3 LEDs, IOUT = 180mA 285 300 315 mV
IFB FB pin input leakage 1 µA
ILED Programmed LED Current R1 = 10Ω
R1 = 3Ω
28.5
30
100
31.5
mA
VIH
VIL
SHDN
¯¯¯¯¯ Logic High
SHDN
¯¯¯¯¯ Logic Low
Enable Threshold Level
Shutdown Threshold Level
0.4
0.8
0.7
1.5
V
V
FSW Switching Frequency 0.8 1.0 1.3 MHz
ILIM Switch Current Limit VIN = 3.6V
VIN = 5V
600
750 mA
RSW Switch “On” Resistance ISW = 100mA 1.0 2.0 Ω
ILEAK Switch Leakage Current Switch Off, VSW = 5V 1 5 µA
TSD Thermal Shutdown 150 ºC
THYST Thermal Hysteresis 20 ºC
VUVLO Under-voltage lock out (UVLO)
Threshold 1.9 V
VOV-DET Over-voltage detection threshold 23 24 V
VOCL Output Clamp voltage “Open LED” 29 V
DC Maximum duty cycle
Minimum duty cycle
92
16 %
Notes:
(1) TSOT23-5 package thermal resistance θJA = 135°C/W when mounted on board over a ground plane.
CAT4139
© Catalyst Semiconductor, Inc. 3 Doc. No. MD-5032 Rev. A
Characteristics subject to change without notice
TYPICAL CHARACTERISTICS
VIN = 5.0V, IOUT = 180mA, TAMB = 25ºC, with typical application circuit unless otherwise specified.
Quiescent Current vs. VIN (Not Switching)
50
100
150
200
3.03.54.04.55.05.5
INPUT VOLTAGE [V]
QUIESCENT CURRENT [μA]
.
VFB = 0.4V
Quiescent Current vs. VIN (Switching)
0.0
0.5
1.0
1.5
2.0
3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
QUIESCENT CURRENT [mA]
FB Pin Voltage vs. Temperature
297
298
299
300
301
302
303
-50 0 50 100 150
TEMPERATURE [ºC]
FB PIN VOLTAGE [mV]
FB Pin Voltage vs. Output Current
290
295
300
305
310
80 100 120 140 160 180 200
OUTPUT CURRENT [mA]
FB PIN VOLTAGE [mV]
Switching Frequency vs. Supply Voltage
0.8
0.9
1.0
1.1
1.2
3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
SWITCHING FREQUENCY [MHz]
Switch ON Resistance vs. Input Voltage
0.0
0.5
1.0
1.5
2.0
3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
SWITCH RESISTANCE [Ω]
CAT4139
Doc. No. MD-5032 Rev. A 4 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
TYPICAL CHARACTERISTICS
VIN = 5.0V, IOUT = 180mA, TAMB = 25ºC, with typical application circuit unless otherwise specified.
Output Current vs. Input Voltage
100
120
140
160
180
200
3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
LED CURRENT [mA]
Output Current Regulation
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
4.5 4.7 4.9 5.1 5.3 5.5
INPUT VOLTAGE [V]
IOUT VARIATION [%]
Efficiency vs. Output Current
75
80
85
90
95
80 100 120 140 160 180 200
OUTPUT CURRENT [mA]
EFFICIENCY [%]
Efficiency vs. Input Voltage
75
80
85
90
95
4.5 4.7 4.9 5.1 5.3 5.5
INPUT VOLTAGE [V]
EFFICIENCY [%]
IOUT = 120mA
IOUT = 180mA
Power-up at 180mA
Switching Waveform
CAT4139
© Catalyst Semiconductor, Inc. 5 Doc. No. MD-5032 Rev. A
Characteristics subject to change without notice
TYPICAL CHARACTERISTICS
VIN = 5.0V, IOUT = 180mA, TAMB = 25ºC, with typical application circuit unless otherwise specified.
Maximum Output Current
0
50
100
150
200
250
300
3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
MAX OUTPUT CURRENT [mA]
VOUT = 9V
VOUT = 14V
Shutdown Voltage
Switch Current Limit
600
650
700
750
800
850
900
4.5 4.7 4.9 5.1 5.3 5.5
INPUT VOLTAGE [V]
SWITCH CURRENT LIMIT [mA]
VOUT = 9V
VOUT = 12V
0.2
0.4
0.6
0.8
1.0
3.03.54.04.55.0
INPUT VOLTAGE [V]
SHUTDOWN VOLTAGE [V]
-40°C
-25°C
85°C
125°C
CAT4139
Doc. No. MD-5032 Rev. A 6 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
PIN DESCRIPTION
VIN is the supply input for the internal logic. The
device is compatible with supply voltages down to
2.8V and up to 5.5V. It is recommended that a small
bypass ceramic capacitor (4.7μF) be placed between
the VIN and GND pins near the device. If the supply
voltage drops below 1.9V, the device stops switching.
SHDN
¯¯¯¯¯ is the shutdown logic input. When the pin is
tied to a voltage lower than 0.4V, the device is in
shutdown mode, drawing nearly zero current. When
the pin is connected to a voltage higher than 1.5V, the
device is enabled.
GND is the ground reference pin. This pin should be
connected directly to the ground plane on the PCB.
SW pin is connected to the drain of the internal CMOS
power switch of the boost converter. The inductor and
the Schottky diode anode should be connected to the
SW pin. Traces going to the SW pin should be as
short as possible with minimum loop area. An over-
voltage detection circuit is connected to the SW pin.
When the voltage reaches 24V, the device enters a
low power operating mode preventing the SW voltage
from exceeding the maximum rating.
FB feedback pin is regulated at 0.3V. A resistor con-
nected between the FB pin and ground sets the LED
current according to the formula:
ILED = 0.3V / R1
The lower LED cathode is connected to the FB pin.
Pin # Name Function
1 SW Switch pin. This is the drain of the internal power switch.
2 GND Ground pin. Connect the pin to the ground plane.
3 FB Feedback pin. Connect to the last LED cathode.
4 SHDN
¯¯¯¯¯ Shutdown pin (Logic Low). Set high to enable the driver.
5 VIN Power Supply input.
SIMPLIFIED BLOCK DIAGRAM
V
IN
V
IN
V
OUT
Current
Sense
Ref
300mV
I
LED
C1
R
S
SHDN
Thermal
Shutdown
& UVLO
1MHz
Oscillator
Over Voltage
Protection
PWM
&
Logic
Driver
C2
GND
SW
FB
+
–
+
–
+
–
CAT4139
© Catalyst Semiconductor, Inc. 7 Doc. No. MD-5032 Rev. A
Characteristics subject to change without notice
DEVICE OPERATION
The CAT4139 is a fixed frequency (1MHz), low noise,
inductive boost converter that provides a constant
current with excellent line and load regulation. The
device uses a high-voltage CMOS power switch
between the SW pin and ground to energize the
inductor. When the switch is turned off, the stored
energy in the inductor is released into the load via the
Schottky diode.
The on/off duty cycle of the power switch is internally
adjusted and controlled to maintain a constant
regulated voltage of 0.3V across the feedback resistor
connected to the feedback pin (FB). The value of the
resistor sets the LED current accordingly (0.3V/R1).
During the initial power-up stage, the duty cycle of the
internal power switch is limited to prevent excessive
in-rush currents and thereby provide a “soft-start”
mode of operation.
In the event of an “Open LED” fault condition, where the
feedback control loop becomes open, the output voltage
will continue to increase. Once this voltage exceeds 24V,
an internal protection circuit will become active and place
the device into a very low power safe operating mode.
Thermal overload protection circuitry has been
included to prevent the device from operating at
unsafe junction temperatures above 150ºC. In the
event of a thermal overload condition the device will
automatically shutdown and wait till the junction
temperatures cools to 130ºC before normal operation
is resumed.
APPLICATION INFORMATION
EXTERNAL COMPONENT SELECTION
CAPACITORS
The CAT4139 only requires small ceramic capacitors
of 4.7μF on the input and 1µF on the output. Under
normal condition, a 4.7µF input capacitor is sufficient.
For applications with higher output power, a larger
input capacitor of 10µF may be appropriate. X5R and
X7R capacitor types are ideal due to their stability
across temperature range.
Inductor
A 22µH inductor is recommended for most of the
CAT4139 applications. In cases where the efficiency is
critical, inductances with lower series resistance are
preferred. Inductors with current rating of 800mA or
higher are recommended for most applications.
Sumida CDRH6D28-220 22µH inductor has a rated
current of 1.2A and a series resistance (D.C.R.) of
128mΩ typical.
Schottky Diode
The current rating of the Schottky diode must exceed
the peak current flowing through it. The Schottky diode
performance is rated in terms of its forward voltage at
a given current. In order to achieve the best efficiency,
this forward voltage should be as low as possible. The
response time is also critical since the driver is
operating at 1MHz. Central Semiconductor Schottky
rectifier CMSH1-40 (1A rated) is recommended for
most applications.
LED Current Setting
The LED current is set by the external resistor R1
connected between the feedback pin (FB) and ground.
The formula below gives the relationship between the
resistor and the current:
R1 = 0.3V / LED current
Table 1. Resistor R1 and LED Current
LED current (mA) R1 [Ω]
20 15
25 12
30 10
100 3
300 1
CAT4139
Doc. No. MD-5032 Rev. A 8 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
OPEN LED PROTECTION
In the event of an “Open LED” fault condition, the
CAT4139 will continue to boost the output voltage
with maximum power until the output voltage
reaches approximately 24V. Once the output
exceeds this level, the internal circuitry immediately
places the device into a very low power mode
where the total input power is limited to about 6mW
(about 1.6mA input current with a 3.6V supply). The
SW pin clamps at a voltage below its maximum
rating of 40V. There is no need to use an external
zener diode between VOUT and the FB pin. A 35V
rated C2 capacitor is required to prevent any
overvoltage damage in the open LED condition.
Open LED Disconnect and Reconnect
Open LED Disconnect
Open LED Output Voltage
15
20
25
30
35
3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
OUTPUT VOLTAGE [V]
Open LED Protection Circuit
VIN
CAT4139
V
IN
V
OUT
L
Schottky 40V
(Central CMSH05-4)
D
4.7µF
C1
1µF
C2
R1
15Ω
FBSHDN
SW
GND
ON
22µH
OFF
Open LED Supply Current
1.0
1.5
2.0
2.5
3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
INPUT CURRENT [mA]
CAT4139
© Catalyst Semiconductor, Inc. 9 Doc. No. MD-5032 Rev. A
Characteristics subject to change without notice
DIMMING CONTROL
There are several methods available to control the
LED brightness.
PWM signal on the SHDN
¯¯¯¯¯ Pin
LED brightness dimming can be done by applying a
PWM signal to the SHDN
¯¯¯¯¯ input. The LED current is
repetitively turned on and off, so that the average
current is proportional to the duty cycle. A 100% duty
cycle, with SHDN
¯¯¯¯¯ always high, corresponds to the
LEDs at nominal current. Figure 1 shows a 1kHz
signal with a 50% duty cycle applied to the SHDN
¯¯¯¯¯ pin.
The recommended PWM frequency range is from 100Hz
to 2kHz.
Figure 1. Switching Waveform
with 1kHz PWM on SHDN
¯¯¯¯¯
Filtered PWM Signal
A filtered PWM signal used as a variable DC voltage
can control the LED current. Figure 2 shows the PWM
control circuitry connected to the CAT4139 FB pin.
The PWM signal has a voltage swing of 0V to 2.5V.
The LED current can be dimmed within a range from
0mA to 20mA. The PWM signal frequency can vary
from very low frequency and up to 100kHz.
Figure 2. Circuit for Filtered PWM Signal
A PWM signal at 0V DC, or a 0% duty cycle, results
in a max LED current of about 22mA. A PWM signal
with a 93% duty cycle or more, results in an LED
current of 0mA.
Figure 3. Filtered PWM Dimming [0V to 2.5V]
LED CURRENT [mA]
25
20
15
10
5
0
0 102030405060708090100
PWM DUTY CYCLE [%]
VIN SW
CAT4139
VIN
0V
2.5V
R1
15Ω
R2
1kΩ
RB
3.1kΩ
RA
3.73kΩ
C3
0.22µF
LED
Current
VFB = 300mV
PWM
Signal
FB
SHDN
GND
CAT4139
Doc. No. MD-5032 Rev. A 10 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
BOARD LAYOUT
The CAT4139 is a high-frequency switching regulator.
The traces that carry the high-frequency switching
current have to be carefully laid out on the board in
order to minimize EMI, ripple and noise in general.
The thicker lines on Figure 4 show the switching
current path. All these traces have to be short and
wide enough to minimize the parasitic inductance and
resistance. The loop shown on Figure 4 corresponds
to the current path when the CAT4139 internal switch
is closed. On Figure 5 is shown the current loop, when
the CAT4139 switch is open. Both loop areas should
be as small as possible.
Capacitor C1 has to be placed as close as possible to
the VIN pin and GND. The capacitor C2 has to be
connected separately to the top LED anode. A ground
plane under the CAT4139 allows for direct connection
of the capacitors to ground. The resistor R1 must be
connected directly to the GND pin of the CAT4139 and
not shared with the switching current loops and any
other components.
Figure 4. Closed-switch Current Loop
Figure 5. Open-switch Current Loop
Figure 6. Recommended PCB Layout
VIN
CAT4139
V
IN
LDV
OUT
R1
C
1
FB
Switch
Closed
SHDN
SW
GND
C
2
VIN
CAT4139
V
IN
LDV
OUT
R1
C
1
FB
Switch
Open
SHDN
SW
GND
C
2
CAT4139
© Catalyst Semiconductor, Inc. 11 Doc. No. MD-5032 Rev. A
Characteristics subject to change without notice
PACKAGE OUTLINES DRAWING
TSOT-23 5-Lead (TD) (1)(2)
Notes:
(1) All dimensions are in millimeters. Angles in degrees.
(2) Complies with JEDEC standard MO-193.
θ
E1 E
A2
A1
e
b
D
c
A
TOP VIEW
SIDE VIEW END VIEW
L1
LL2
SYMBOL MIN NOM MAX
A1.00
A1 0.01 0.05 0.10
A2 0.80 0.87 0.90
b0.30 0.45
c 0.12 0.15 0.20
D 2.90 BSC
E 2.80 BSC
E1 1.60 BSC
e0.95TYP
L 0.30 0.40 0.50
L1 0.60 REF
L2 0.25 BSC
θ0º 8º
CAT4139
© Catalyst Semiconductor, Inc. 12 Doc. No. MD-5032 Rev. A
Characteristics subject to change without notice
EXAMPLE OF ORDERING INFORMATION1
SERIES LED DRIVERS
Part Numbe
r
Descri
p
tion
CAT4137 CMOS Boost Converter
–
White LED Driver
CAT4237 Hi
g
h Volta
g
e CMOS Boost White LED Driver
CAT4238 Hi
g
h Efficienc
y
10 LED Boost Converter
CAT4139 22V Hi
h Current Boost White LED Driver
CAT4240 6 Watt Boost LED Driver
Notes:
(1) All packages are RoHS-compliant (Lead-free, Halogen-free).
(2) The standard lead finish is NiPdAu.
(3) The device used in the above example is a CAT4139–GT3 (TSOT-23, NiPdAu, Tape & Reel).
(4) For additional package and temperature options, please contact your nearest Catalyst Semiconductor Sales office.
Prefix Device # Suffix
CAT 4139 TD – G T3
Optional
Company ID
Product Number
4139
Tape & Reel
T: Tape & Reel
3: 3000/Reel
Package
TD: TSOT-23
Lead Finish
G: NiPdAu
REVISION HISTORY
Date Rev. Reason
11/06/2007 A Initial Issue
Catalyst Semiconductor, Inc.
Corporate Headquarters
2975 Stender Way
Santa Clara, CA 95054
Phone: 408.542.1000 Document No: MD-5032
Fax: 408.542.1200 Revision: A
www.catsemi.com Issue date: 11
/
06
/
07
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© Catalyst Semiconductor, Inc.
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