CAT4106 D

CAT4106
6 W Quad Channel DC/DC
LED Driver with Diagnostics
Description
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1
PIN CONNECTIONS
1
LED1
GND
FAULT
PGND
FB
SW
EN/PWM
NC
1
LED1
GND
FAULT
PGND
VFMAX
VFMIN
CTRL
VIN
TAB
is
GND
NC
EN/PWM
SW
FB
Four LED Channels with Tight Current Matching
Integrated DC/DC Boost Converter
Up to 6 W LED Total Output Power
Up to 92% Efficiency
Low Dropout LED Channels (500 mV at 175 mA)
High Frequency PWM Interface (up to 2 kHz)
Adjustable Short/Open LED Detection
Programmable LED Channel Current
Adjustable LED Channel Voltage
Thermal Shutdown Protection
16−lead TQFN 4 x 4 mm and TSSOP Packages
These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
LED2
LED3
LED4
RSET
VFMAX
VFMIN
CTRL
VIN
TAB
is
GND
Features
•
•
•
•
•
•
•
•
•
•
•
•
1
TSSOP−16
YP SUFFIX
CASE 948AP
TQFN−16
HV4 SUFFIX
CASE 510AE
RSET
LED4
LED3
LED2
The CAT4106 is an integrated multi−channel LED driver and high
power DC/DC converter suitable for powering backlighting
applications up to a total of 6 watts. Up to four matched LED strings
can be accurately programmed with uniform drive current set by a
single external resistor. Each output channel is suitable for LED string
voltages of up to 36 V. The driver automatically adjusts the output
voltage to drive the highest forward voltage string with the minimum
headroom voltage maximizing the efficiency.
High resolution dimming control is achieved by the EN/PWM logic
pin which supports multiple frequencies. This ensures precise PWM
dimming control while the device remains fully biased. In addition,
when held at logic low, the device to enter a full shutdown “zero”
current mode.
External programming resistors set the minimum and maximum
voltage limits for the acceptable “window of operation” for LED
strings. Any channel which fails to regulate within the window (Open
or Short LED) is detected and flagged on the FAULT logic output
(active low, open−drain).
The device is available in a 16−lead TQFN 4 mm x 4 mm and
TSSOP with exposed pad packages.
(Top Views)
MARKING DIAGRAMS
4106Y
CDAL
CDAL = CAT4106HV4−GT2
4106Y = CAT4106YP−T2
Applications
• LCD Backlight Lighting
• Automotive and General Purpose Lighting
ORDERING INFORMATION
Device
Package
Shipping
CAT4106HV4−GT2
(Note 1)
TQFN−16
(Pb−Free)
2,000/
Tape & Reel
CAT4106YP−T2
(Note 1)
TSSOP−16
(Pb−Free)
2,000/
Tape & Reel
1. NiPdAu Plated Finish (RoHS−compliant)
2. Matte−Tin Plated Finish (RoHS−compliant)
© Semiconductor Components Industries, LLC, 2014
June, 2014 − Rev. 4
1
Publication Order Number:
CAT4106/D
CAT4106
L
VL
3 V to 24 V
4.7 mF
VIN
VIN
3 V to 5.5 V C1
1 mF
C3
10 mF/
50 V
R4
R6
SW VFMAX
VFMIN
R5
CAT4106
OFF... ON... DIM
R1
D
47 mH
C2
R7
EN/PWM
RSET
LED1
LED2
LED3
R2 20 kW
LED4
CTRL
FAULT
FB GND PGND
R3
20 kW
VIN
R8
LED Fault Detection
(open drain pull−down)
Figure 1. Typical Application Circuit
Table 1. ABSOLUTE MAXIMUM RATINGS
Parameters
Ratings
Units
VIN, RSET, EN/PWM, CTRL, FB, FAULT
−0.3 V to 6
V
VFMIN, VFMAX
−0.3 V to 6
V
LED1, LED2, LED3, LED4
−0.3 V to 25
V
SW (internally clamped to 40 V)
50
V
Storage Temperature Range
−65 to +150
_C
Junction Temperature Range
−40 to +150
_C
300
_C
Lead Temperature
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
Table 2. RECOMMENDED OPERATING CONDITIONS
Parameter
Range
Units
VIN
3.0 to 5.5
V
Inductor Drive Voltage
3.0 to 24
V
LED String Forward Voltage per channel
up to 36
V
Ambient Temperature Range
−40 to +85
_C
ILED per LED pin
10 to 175
mA
Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond
the Recommended Operating Ranges limits may affect device reliability.
3. Typical application circuit with external components is shown above.
Table 3. RECOMMENDED EN/PWM TIMING
(For 3.0 ≤ VIN ≤ 5.5 V, over full ambient temperature range −40 to +85°C.)
Min
Typ
Max
Units
LED setup time from shutdown
Name
10
40
100
ms
TLO
EN/PWM low time
0.2
2000
ms
THI
EN/PWM high time
100
Symbol
TLEDSETUP
TPWRDWN
TLEDSET
Conditions
ms
EN/PWM low time to shutdown delay
8
LED current settling time
ILED = 100 mA
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2
0.2
ms
ms
CAT4106
TLEDSETUP
THI
TPWRDWN
TLO
EN/PWM
SHUTDOWN
DIMMING
100% BRIGHTNESS
POWERDOWN
SHUTDOWN
LED CURRENT
DEVICE
QUIESCENT CURRENT
Figure 2. CAT4106 EN/PWM Timing
Table 4. ELECTRICAL OPERATING CHARACTERISTICS
VIN = 5 V, VL (inductor drive voltage) = 12 V, TAMB = 25°C (over recommended operating conditions unless specified otherwise)
Symbol
IQ
Description
Conditions
Min
Max
Units
2.5
2.0
3.4
2.9
3.5
3.0
4.4
3.9
mA
1
mA
1.3
V
V
kW
VIN Operating Current
Switching
Not Switching
Switching
Not Switching
ISD
VIN input shutdown Current
VEN = 0 V
VIH
VIL
REN
EN/PWM
Logic High Threshold
Logic Low Threshold
Internal Pull−Down Resistor
Device Enable Level
Disable/PWM Level
VUVLO
Undervoltage lockout (UVLO)
VIN pin voltage
TSD
Thermal Shutdown Threshold
THYS
Thermal Hysteresis
VRSET
RSET regulation voltage
10 mA < IRSET < 2 mA
RSET to LED Current gain ratio
30 mA LED current
100
LED Channel Dropout Voltage
ILED = 175 mA
0.5
DILED
LED Channel Matching
0.5 V < VLED < 5 V
ILED−OFF
LED Channel leakage
Channel is Off
VVFMAX
O/C Detect voltage threshold
1.15
VVFMIN
S/C Detect voltage threshold
1.15
VCTRL
ICTRL
CTRL pin voltage accuracy
CTRL pin maximum load
Offset to Lowest LED output
IFAULT
Pull−down Drive Current
Open Drain Leakage Current
FAULT is Active (0.1 V bias)
FAULT is Inactive
FB Pin control voltage
FB pin input leakage current
Normal switching
mode regulation
ILED/IRSET
VDO
VFB
IFB
FSW
ISWMAX
RSW
DCMAX
DCMIN
ISWLEAK
OVPSW
SW Pin
Switching Frequency
Switch Pin Current Limit
Switch Pin On−resistance
Maximum Duty Cycle
Minimum Duty Cycle
Switch Leakage Current
Over Voltage Protection Detect
(ILED = 30 mA)
(ILED = 30 mA)
(ILED = 60 mA)
(ILED = 60 mA)
Typ
0.4
100
0.8
0.7
200
300
2.0
V
150
_C
_C
20
ISW = 500 mA
Prior to Current Limiting
Prior to Pulse−Skipping
VSW = 20 V
Enters Low Power mode
1.17
−5
1.20
±1
1.23
V
V
+5
%
1
mA
1.20
1.25
V
1.20
1.25
V
− 0.1
25
0
+ 0.1
V
mA
1
2
1
mA
mA
285
300
315
1
mV
mA
0.7
0.8
1.0
1.0
1.0
96
5
1.3
MHz
A
W
%
%
mA
V
5
40
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product
performance may not be indicated by the Electrical Characteristics if operated under different conditions.
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CAT4106
TYPICAL ELECTRICAL OPERATING CHARACTERISTICS
8
1.30
6
1.25
RSET VOLTAGE (V)
QUIESCENT CURRENT (mA)
(VIN = 5 V, VL = 12 V, TAMB = 25°C, typical application circuit unless otherwise specified.)
switching
4
not switching
2
0
0.5
1.0
1.5
2.0
3.0
3.5
4.0
4.5
5.0
RSET CURRENT (mA)
VIN SUPPLY (V)
Figure 3. Quiescent Current vs. RSET Current
Figure 4. RSET Voltage vs. VIN Supply
1.30
140
1.25
120
GAIN
RSET VOLTAGE (V)
1.15
1.10
0
1.20
1.15
5.5
100
80
1.10
−50
60
0
50
100
150
20
60
100
140
TEMPERATURE (°C)
LED CURRENT (mA)
Figure 5. RSET Voltage vs. Temperature
Figure 6. ILED/IRSET Gain vs. LED Current
200
200
175
175
150
150
LED CURRENT (mA)
LED CURRENT (mA)
1.20
125
100
75
50
180
125
100
75
50
25
25
0
0
0
0.2
0.4
0.6
0.8
3.0
1.0
3.5
4.0
4.5
5.0
5.5
LED PIN VOLTAGE (V)
VIN SUPPLY (V)
Figure 7. LED Channel Current vs. LED Pin
Voltage
Figure 8. LED Channel Current vs. VIN Supply
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CAT4106
TYPICAL ELECTRICAL OPERATING CHARACTERISTICS
0.9
30
0.8
25
FAULT DRIVE RDSON (W)
LED PIN VOLTAGE (V)
(VIN = 5 V, VL = 12 V, TAMB = 25°C, typical application circuit unless otherwise specified.)
0.7
0.6
0.5
20
15
10
R2 = R3 = 24 kW
5
0.4
3.0
3.5
4.0
4.5
5.0
3.0
5.5
4.5
5.0
5.5
VIN SUPPLY (V)
Figure 9. LED Channel Voltage vs. VIN Supply
Figure 10. FAULT Drive RDSON vs. VIN Supply
1.2
SWITCHING FREQUENCY (MHz)
SWITCH RESISTANCE (W)
4.0
VIN SUPPLY (V)
2.0
1.5
1.0
0.5
1.1
1.0
0.9
0.8
0
3.0
3.5
4.0
4.5
5.0
3.0
5.5
3.5
4.0
4.5
5.0
VIN SUPPLY (V)
VIN SUPPLY (V)
Figure 11. Switch Resistance vs. VIN Supply
Figure 12. Switching Frequency vs. VIN
Supply
5.5
5
POWERDOWN DELAY (ms)
1200
SW CURRENT LIMIT (mA)
3.5
1100
1000
900
800
700
4
3
2
1
0
600
3.0
3.5
4.0
4.5
5.0
3.0
5.5
3.5
4.0
4.5
5.0
VIN SUPPLY (V)
VIN SUPPLY (V)
Figure 13. Switching Current Limit vs. VIN
Supply
Figure 14. Powerdown Delay vs. VIN Supply
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5.5
CAT4106
TYPICAL ELECTRICAL OPERATING CHARACTERISTICS
(VIN = 5 V, VL = 12 V, TAMB = 25°C, typical application circuit unless otherwise specified.)
100
TOTAL LED CURRENT (%)
0.95
VHI
0.90
0.85
VLO
0.80
0.75
10
100 Hz
1 kHz
1
0.70
3.0
3.5
4.0
4.5
5.0
1
5.5
10
100
VIN SUPPLY (V)
DUTY CYCLE (%)
Figure 15. EN/PWM Threshold vs. VIN Supply
Figure 16. PWM Duty Cycle vs. LED Current
Figure 17. PWM Dimming 100 Hz
Figure 18. PWM Dimming 1 kHz
200
MAX ILED PER CHANNEL (mA)
EN/PWM THRESHOLD (V)
1.00
VOUT = 20 V
150
25 V
30 V
100
50
0
2
4
6
8
10
12
14
VL (V)
Figure 19. Power−Up 4 x 10 LEDs, 50 mA per
Channel
Figure 20. Maximum LED Current vs. VL
Supply
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16
CAT4106
TYPICAL ELECTRICAL OPERATING CHARACTERISTICS
100
95
95
EFFICIENCY (%)
100
90
85
80
90
85
80
VOUT = 19 V
VOUT = 24 V
75
75
70
70
4.5
4.7
4.9
5.1
5.3
8
5.5
10
12
14
INPUT VOLTAGE (V)
INDUCTOR VOLTAGE (V)
Figure 21. Efficiency vs. VIN (VIN = VL)
Figure 22. Efficiency vs. VL (VIN = 5 V)
100
95
EFFICIENCY (%)
EFFICIENCY (%)
(VIN = 5 V, VL = 12 V, 20 mA per channel (80 mA total output current), TAMB = 25°C, typical application circuit unless otherwise specified.)
90
85
80
75
70
40
80
120
160
200
OUTPUT CURRENT (mA)
Figure 23. Efficiency vs. Output Current
(9−LED String)
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240
16
CAT4106
Table 5. PIN DESCRIPTION
TQFN−16
Name
TSSOP−16
LED1
1
LED1 cathode terminal
GND
2
Signal Ground reference
FAULT
3
Open/Short LED Fault detection output (active−low)
PGND
4
Power Ground Reference (DC/DC Power Switch)
Function
FB
5
Feedback reference (300 mV) for setting LED channel operating voltage
SW
6
Internal power FET switch drain connection
EN/PWM
7
Device Enable (active high) and PWM control input
N.C.
8
Not connected
VIN
9
Supply voltage for the device
CTRL
10
LED channel operating voltage (lowest of all 4 channels)
VFMIN
11
Comparator input for setting the LED string short−circuit voltage limit
VFMAX
12
Comparator input for setting the LED string open−circuit voltage limit
RSET
13
RSET resistor pin for setting the LED channel operating current
LED4
14
LED4 cathode terminal
LED3
15
LED3 cathode terminal
LED2
16
LED2 cathode terminal
TAB
TAB
Thermal pad (connect to GND and PGND)
Pin Descriptions
VIN is the supply pin for the device. The supply input
current needed for normal operation is approximately 2 mA
plus 3 times IRSET pin current. During intervals of PWM
dimming, or whenever the converter is not switching, the
supply current will decrease by around 1 mA. The voltage
applied at VIN should be kept between 3 V and 5.5 V. A
small ceramic bypass capacitor of 0.1 mF or greater is
recommended to be in close proximity to the VIN pin.
EN/PWM is the device Enable and PWM dimming control
input for all LED channels. Guaranteed levels of logic high
and logic low are set at 1.3 V and 0.4 V respectively. During
normal PWM dimming, the entire device remains fully
biased and only the LED channels are pulsed on/off. The
device will only enter zero current shutdown mode after the
EN/PWM is help low for at least 5 ms typically. This pin has
an internal pull−down resistor of 200 kW.
RSET is the voltage regulated control pin for sensing the
desired programming current level to be applied on all LED
channels. During normal operation, the RSET pin is kept at
1.2 V and accurately monitors the current level in the
externally applied R1 resistor. The current transfer ratio
from RSET pin current to LED pin current is 100.
LED1 to LED4 provide the regulated current source for
driving each of the LED strings with a tightly matched
constant current. To ensure optimal performance, the bias
voltage on the LED channels should be set at a nominal
0.6 V or higher. Each channel is capable of driving a current
up to 175 mA. All channels immediately enter a high
impedance mode whenever the EN/PWM is taken LOW.
CTRL pin is a multiplexer output which selects the lowest
operating voltage appearing on any of the four LED output
drive channels. This control signal represents the cathode
terminal voltage of the LED string with greatest forward
voltage (VF). An external resistor network from CTRL to FB
can be used to set the lowest operating voltage of each
channel. External current loading of the CTRL pin is
recommended to be less than 25 mA.
FB is the voltage feedback control pin for the internal high
power DC/DC converter. This pin has a high impedance
input and its voltage remains accurately regulated to 0.3 V
during normal steady state operation.
SW pin is the drain terminal of the high voltage CMOS
power switch which has a typical on−resistance of 1 W and
is current limited to 1 A typically. An overvoltage protection
circuit places the device in a soft−clamping low power mode
if the voltage transients exceed 40 V.
VFMIN pin uses a pair of external resistors (R6 & R7) to
program the worst case, minimum LED string forward
voltage (VFMIN) expected in the specific application. If any
LED string enters full regulation before the output voltage
reaches VFMIN, the output will continue to rise to VFMIN
where it will signal an LED short−circuit and a fault
condition will be flagged. The detection only works during
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CAT4106
power−up and works best when VFMIN is set at least twice
the value of VL. The VFMIN input circuitry consists of a
comparator referenced to 1.2 V. A typical value for resistor
R7 is around 20 kW. R6 can be calculated as follows:
R6 + R7
ǒ
A typical value for resistor R5 is 20 kW. R4 can be
calculated as follows:
R4 + R5
Ǔ
V FMIN
*1
1.2 V
ǒ
Ǔ
V FMAX
*1
1.2 V
If this detection feature is not needed, the VFMAX pin
must be tied to ground.
FAULT is an open−drain, active−low, logic signal which
becomes active during an LED short−circuit or open−circuit
condition. The pin must be connected to a pull−up resistor
of around 100 kW tied to VIN. The drive pull−down
resistance (when active) is typically less than 100 W. The
diagnostic sequence used to determine a fault condition is
initiated when the device is first enabled.
PGND pin is the source connection terminal of the high
voltage CMOS power switch in the DC/DC converter. The
inductor supply bypass capacitor should be connected in
close proximity to the PGND pin. The return current from
PGND should be connected to the PCB ground plane.
GND is the ground reference pin for the device. All analog
control voltages are referenced to this pin. In addition, all
LED drive currents are conducted through the GND pin.
TAB is the thermal pad connection of the package and
should be connected to PCB ground plane.
If this detection feature is not needed, the VFMIN pin
must be tied to ground.
VFMAX pin uses a pair of external resistors (R4 & R5) to
program the worst case, maximum LED string forward
voltage (VFMAX) expected in the specific application. If any
LED string fails to become regulated before the
programmed voltage is reached, the string will be
considered to contain LEDs which are open−circuit and a
fault condition will be flagged. When an open−circuit is
flagged, the individual channel that causes the open−circuit
is internally flagged and subsequently ignored. In the event
that all channels are detected as being Open−LED, the
Output Voltage (top LED Anode) will stabilize at the
VFMAX programmed voltage. The VFMAX input circuitry
consists of a comparator referenced to 1.2 V.
Block Diagram
L
VL
D
C3
R4
R6
R5
SW
300 mV
R7
LED
Cluster
N_Series
M_Parallel
VFMIN
VFMAX
FAULT
OVP
Controller
Ctrl/Fault
Detector
mC Diagnostics
CTRL
1A
1W
1 MHz PWM
Controller
R2
LED1
FB
LED1
LED2
LED3
LED4
Supply
VIN
Shutdown
Delay
EN/DIM
System
EN/SD
I1
PWM_DIM
I2
I3
I4
0 − 175 mA
Drive Control
IRSETx100
200 kW
R3
GND
RSET
LEDn
PGND
R1
Figure 24. CAT4106 Simplified Functional Block Diagram
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CAT4106
LED Detection
Device Operation
In a typical application, the CAT4106 drives an LED array
consisting of up to four separate strings. A single external
resistor value is used to select the drive level in all output
channels. Each channel provides a very well regulated and
tightly matched bias current on all LED strings.
An integrated DC/DC boost converter is used to generate
the high voltage output required to power the LED strings.
Up to a maximum of 6 W of LED power can be delivered
when powered from a 12 V supply.
To offer improved performance, the device also allows the
user to set the operating voltage level on the output drive
channels. A pair of external resistors is used to control the
nominal channel voltage, during normal operation. The
resulting output voltage (LED anodes) will be equal to the
sum of the adjusted channel voltage plus the maximum
forward voltage present on any string.
The CAT4106 provides four tightly matched current sinks
to accurately regulate LED current in each channel. Up to
175 mA per channel can be programmed by selecting a
suitable value for the external R1 resistor (connected
between RSET and GND pins).
The CAT4106 detects failure conditions related to the
LED load, such as if one of the LED strings has been
disconnected (Open−LED) or if one LED string has a lower
LED pin voltage than expected (Short−LED). Either
condition is flagged by turning on the open−drain output on
the FAULT pin. The Open−LED detection is active in
normal operation. The Short−LED detection is only active
during power−up, just after the EN/PWM input goes from
low to high. If in normal operation (LEDs are in regulation)
a short−LED condition occurs, it will not be detected.
LED Current Setting
The CAT4106 provides four tightly matched current sinks
to accurately regulate LED current in each channel. The
LED current is set by the external resistor R1 connected
between the RSET pin and ground. The following formula
gives the relationship between the resistor value and the
LED current per channel.
R1 [ 103
Figure 25. Cold Power−Up Short−LED Detection
1.2 V
LED current per channel
Table 6. RESISTOR R1 AND LED CURRENT
LED Current per Channel (mA)
R1 (W)
10
12.4 k
20
6.19 k
30
4.12 k
50
2.49 k
100
1.24 k
150
820
Figure 26. Normal Operation Open−LED Detection
The test condition in Figure 25 is with one LED pin
shorted to the output (top LED anode). The test condition in
Figure 26 is with one LED pin floating or disconnected. In
both cases, the CAT4106 is set to drive 50 mA per channel.
Setting the Channel Voltage
Setting VFMIN Level (Short−LED)
Each LED channel typically requires less than 0.5 V of
headroom for full load operation. The lowest channel
operating voltage can be controlled and programmed via the
external resistor network connected between, CTRL, FB
and GND as shown in Figure 24.
The VFMIN level represents the minimum level expected
for the LED string voltage “window of operation”. This
voltage setting is based on the number of series LEDs being
used and the expected minimum forward voltage VF during
normal operation.
Example: Consider a string of 6 LEDs in series, with each
LED having a VF range of 3.5 V ± 0.5 V. Since the
minimum VF of each LED is 3.0 V the overall lowest
expected string voltage would be 18 V. Any string voltage
of less than 18 V is considered as a short−circuit fault in one
or more of the series LEDs.
Lowest LED pin voltage + V FB
R2 ) R3
R3
For most applications, a gain of 2x (R2 equals R3) is
recommended. The CTRL output pin has optimal
performance when loaded with around 15 mA, which
equates to an R3 resistor value of 20 kW.
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CAT4106
During PWM dimming, the recommended minimum
pulse width interval (either High or Low) is 0.2 ms. The
recommended maximum pulse width during PWM
dimming is 2.0 ms, however this only applies to the Low
pulse interval. Pulse durations extending past 2.0 ms may
cause the device to enter full shutdown mode. The LED
channel response time is longer if the device has been in
shutdown mode.
For most applications, a maximum dimming resolution
can be achieved with PWM clock frequencies in the range
of 500 Hz to 2 kHz. Pulse width intervals of 1 ms, allows up
to 1000:1 dimming ratio at 1 kHz PWM frequency.
The external resistor R6 value needed to set a VFMIN
level of 18 V is calculated as follows:
R6 + R7
18 V
ǒ1.2
* 1Ǔ
V
For R7 = 20 kW, R6 = 280 kW.
Setting VFMAX Level (Open−LED)
The VFMAX level represents the maximum level expected
for the LED string voltage “window of operation”. This
voltage setting is based on the number of series LEDs being
used and the expected maximum VF during normal operation.
Example: Consider a string of 6 LEDs in series, with each
LED having a VF range of 3.5 V ± 0.5 V. Since the
maximum VF of each LED is 4.0 V, the overall maximum
expected string voltage would be 24 V. Any string voltage
which appears greater than 24 V would be considered as
containing an open−circuit in one or more of the series
LEDs. The external resistor R4 value needed to set a
VFMAX level of 24 V is calculated as follows:
R4 + R5
One or Two LED String Applications
The CAT4106 can be used to drive one or two strings of
LEDs by connecting together some LED pins. Also for
applications requiring LED current greater than 175 mA,
LED channels can be tied together, assuming the supply is
suitable to drive the load. Figure 27 shows a typical
application for driving a single string of LEDs. Note:
VFMIN is disabled for one string.
24 V
ǒ1.2
* 1Ǔ
V
D
L
VL
C2
For R5 = 20 kW, R4 = 380 kW.
In normal operation, the LED string which has the largest
VF will be used to set the VCTRL/VFB voltage levels. If the
largest string voltage tries to exceed VFMAX setting, it will
no longer be allowed to control the voltage level of
VCTRL/VFB (i.e. it will be ignored) and subsequently the
next largest LED string voltage will then be used in the
control loop. All remaining functional LED channels will
continue to operate as normal. If a disconnected LED string
is reconnected, the FAULT flag remains on and the channel
disabled until the device has been re−enabled with the EN
pin going from low to high.
If all LED channels are detected as being open−circuit,
then the boost converter will limit the output voltage to the
VFMAX setting. This eliminates the need for an external
protection zener.
C3
VIN
VIN
C1
R4
R6
R5
R7
SW VFMAX
VFMIN
CAT4106
OFF... ON... DIM...
EN/PWM
RSET
R2
R1
LED1
LED2
LED3
LED4
VCTRL
FAULT
FB GND PGND
VIN
R8
R3
LED Fault Detection
(open drain pull−down)
Figure 27. Application Circuit for One LED String
Figure 28 shows a typical application for driving two
strings of LEDs. The LED current is equal to two times the
channel current.
Enable and PWM Dimming Control
D
L
VL
EN/PWM input signal provides two independent
functions. The first function is to enable and disable the
entire device. The second function is to apply PWM
dimming on the output channels while the chip remains fully
enabled. Applying logic high on the EN/PWM input will
power up the device. The device will continue to remain
powered up, even in the presence of PWM signals being
applied. To disable the device into complete system
shutdown mode, a logic low must be applied to the
EN/PWM input for typically 5 ms.
The duty cycle applied at the EN/PWM is directly applied
to all the output channels. Each time the input is taken low,
all output channels will immediately be switched off and the
channels will resume normal operation when the PWM is
taken back high. The response time of the channels when
switching ON or OFF is typically 0.2 ms.
C2
C3
VIN
VIN
C1
R4
R6
R5
R7
SW VFMAX
VFMIN
CAT4106
OFF... ON... DIM...
EN/PWM
RSET
R2
R1
LED1
LED2
LED3
LED4
VCTRL
FAULT
FB GND PGND
VIN
R8
R3
LED Fault Detection
(open drain pull−down)
Figure 28. Application Circuit for Two LED Strings
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11
CAT4106
Application Information
External Component Selection
Recommended Layout
The board layout should provide good thermal dissipation
through the PCB. Multiple via can be used to connect the tab
of the CAT4106 to a large ground plane underneath the
package.
Input capacitor C1 should be placed as close to the driver
IC as possible. The RSET resistor (R1) and channel voltage
setting resistor (R3) should have a Kelvin connection to the
GND pin of the CAT4106.
Capacitors
The CAT4106 requires small ceramic capacitors of 1 mF
on the VIN pin (C1), 4.7 mF on the inductor input (C2), and
10 mF on the output (C3). Under normal condition, a 4.7 mF
input capacitor (C2) is sufficient. The voltage rating of each
capacitor should be compatible with the maximum voltage
applied. For the output, a 50 V rated capacitor (C3) is
recommended in case the LED becomes disconnected
(Open−LED condition). X5R and X7R capacitor types are
ideal due to their stability across temperature range.
Inductor
A 47 mH inductor is recommended for most applications.
In cases where the efficiency is critical, inductances with
lower series resistance are preferred. Inductors with current
rating of 1 A or higher are recommended for most
applications. Coiltronics DR73−470 inductor rated at 1.08 A
is recommended for most applications.
Schottky Diode
The current rating of the Schottky diode (D) must exceed
the peak current flowing through it. A 1 A rated Schottky
diode is recommended. 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 1 MHz. NXP
PMEG6010CEJ (60 V / 1 A rated) Schottky barrier rectifier
is recommended for most applications.
Figure 29. Recommended Layout for TQFN−16
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12
CAT4106
PACKAGE DIMENSIONS
TQFN16, 4x4
CASE 510AE−01
ISSUE A
A
D
DETAIL A
E2
E
PIN#1 ID
PIN#1 INDEX AREA
TOP VIEW
SIDE VIEW
SYMBOL
MIN
NOM
MAX
A
0.70
0.75
0.80
A1
0.00
0.02
0.05
A3
BOTTOM VIEW
e
b
0.20 REF
b
0.25
0.30
0.35
D
3.90
4.00
4.10
D2
2.00
−−−
2.25
E
3.90
4.00
4.10
E2
2.00
−−−
2.25
e
L
D2
A1
L
DETAIL A
0.65 BSC
0.45
−−−
A
0.65
Notes:
(1) All dimensions are in millimeters.
(2) Complies with JEDEC MO-220.
A1
A3
FRONT VIEW
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13
CAT4106
PACKAGE DIMENSIONS
TSSOP16, 4.4x5 EXPOSED PAD
CASE 948AP−01
ISSUE A
b
X
c
Y
E1 E
L1
PIN#1
IDENTIFICATION
e
L
θ1
TOP VIEW
EXPOSED THERMAL PAD ZONE
END VIEW
BOTTOM VIEW
X ± 0.076
D
A2
SIDE VIEW
SYMBOL
A
A1
A2
b
c
D
E
E1
e
L
L1
N
P
R
S
θ
X
Y
MIN
A
A1
NOM
MAX
1.10
0.15
0.95
0.30
0.20
5.10
6.50
4.50
0.05
0.85
0.19
0.13
4.90
6.30
4.30
Y ± 0.076
P
R
0.65 BSC
1.00 REF
0.45
0.90
6.50
4.60
0.37
0.75
1.00
6.70
4.80
0.47
0º
8º
S
e
LAND PATTERN
Notes:
(1) All dimensions are in millimeters. Angles in degrees.
(2) Complies with JEDEC MO-153 variations ABT.
2.74 REF
2.74 REF
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14
N
CAT4106
Example of Ordering Information
4.
5.
6.
7.
8.
All packages are RoHS−compliant (Lead−free, Halogen−free).
The standard plated finish is NiPdAu.
TSSOP only available in Matte−Tin plated finish.
For additional temperature options, please contact your nearest ON Semiconductor Sales office.
For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
ON Semiconductor and
are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks,
copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent−Marking.pdf. SCILLC
reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any
particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without
limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications
and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC
does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for
surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where
personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and
its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly,
any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture
of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
PUBLICATION ORDERING INFORMATION
LITERATURE FULFILLMENT:
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Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada
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Order Literature: http://www.onsemi.com/orderlit
For additional information, please contact your local
Sales Representative
CAT4106/D
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