CAT3614
4-Channel 1-Wire LED
Driver in 3 x 3 mm Package
Description
The CAT3614 is a high efficiency 1x/1.5x fractional charge pump
with programmable dimming current in four LED channels. To ensure
uniform brightness in LCD backlight applications, each LED channel
delivers an accurate regulated current.
Low noise and input ripple is achieved by operating at a constant
switching frequency of 1 MHz which allows the use of small external
ceramic capacitors. The 1x/1.5x fractional charge pump supports a
wide range of input voltages from 3 V to 5.5 V with efficiency up to
91%, and is ideal for Li−Ion battery powered devices.
The EN/DIM logic input provides a 1−wire EZDimt interface for
dimming control of the LEDs. When enabled, a series of clock pulses
reduces the LED brightness in 1 mA steps on each negative going
edge. Currents from 0 mA to 31 mA are supported.
The device is available in the tiny 12−pad TDFN 3 x 3 mm package
with a max height of 0.8 mm.
C1+
EN/DIM
Features
C1−
LED4
C2−
LED3
C2+
LED2
GND
LED1
•
•
•
•
•
•
•
•
•
•
•
•
•
Drives up to 4 LED Channels
1−wire EZDimt Programmable LED Current
Accurate 1 mA Dimming Level
Power Efficiency up to 91%
Fractional Pump 1x/1.5x
Low Noise Input Ripple
Fixed High Frequency Operation 1 MHz
“Zero” Current Shutdown Mode
Soft Start and Current Limiting
Short Circuit Protection
Thermal Shutdown Protection
TDFN 12−pad 3 mm x 3 mm Package
These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
Applications
•
•
•
•
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TDFN−12
HV2 SUFFIX
CASE 511AN
PIN CONNECTIONS
1
VIN
VOUT
(Top View)
MARKING DIAGRAM
HAAA
AXXX
YWW
HAAC
AXXX
YWW
HAAA = CAT3614HV2-T2
HAAC = CAT3614HV2-GT2
A = Assembly Location
XXX = Last Three Digits of Assembly Lot Number
Y = Production Year (Last Digit)
WW = Production Week (Two Digit)
ORDERING INFORMATION
LCD Display Backlight
Cellular Phones
Digital Still Cameras
Handheld Devices
Device
Package
Shipping
CAT3614HV2−T2
(Note 1)
TDFN−12
(Pb−Free)
2,000/
Tape & Reel
CAT3614HV2−GT2
(Note 2)
TDFN−12
(Pb−Free)
2,000/
Tape & Reel
1. Matte−Tin Plated Finish (RoHS−compliant).
2. NiPdAu Plated Finish (RoHS−compliant).
© Semiconductor Components Industries, LLC, 2010
April, 2010 − Rev. 2
1
Publication Order Number:
CAT3614/D
CAT3614
1 mF
VIN
3 V to
5.5 V
CIN
C1+ C1− C2+ C2−
VIN
VOUT
CAT3614
1 mF
ENABLE/
DIMMING
1 mF
EN/DIM
GND
LED1
LED2
LED3
LED4
VOUT
COUT
1 mF
20 mA
Figure 1. Typical Application Circuit
NOTE:
Unused LED channels must be connected to VOUT.
Table 1. ABSOLUTE MAXIMUM RATINGS
Parameter
Rating
Unit
VIN, LEDx voltage
6
V
VOUT, C1±, C2± voltage
7
V
EN/DIM voltage
VIN + 0.7 V
V
Storage Temperature Range
−65 to +160
°C
Junction Temperature Range
−40 to +150
°C
300
°C
Lead Temperature
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 2. RECOMMENDED OPERATING CONDITIONS
Parameter
Range
Unit
3 to 5.5
V
−40 to +85
°C
ILED per LED pin
0 to 31
mA
Total Output Current
0 to 124
mA
VIN
Ambient Temperature Range
NOTE:
Typical application circuit with external components is shown above.
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2
CAT3614
Table 3. ELECTRICAL OPERATING CHARACTERISTICS
VIN = 3.6 V, EN = High, ambient temperature of 25°C (over recommended operating conditions unless specified otherwise).
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
0.3
1
0.5
3
1
8
mA
IQ
Quiescent Current
1x mode, no load
1.5x mode, no load
IQSHDN
Shutdown Current
VEN = 0 V
1
mA
ILED−ACC
LED Current Accuracy
1 mA ≤ ILED ≤ 31 mA
±3
±8
%
ILED−DEV
LED Channel Matching
(ILED − ILEDAVG) / ILEDAVG
±3
±7
%
ROUT
Output Resistance (open loop)
1x mode, IOUT = 100 mA
1.5x mode, IOUT = 100 mA
0.4
2.6
1
7
W
FOSC
Charge Pump Frequency
0.8
1
1.3
MHz
ISC_MAX
Output short circuit Current Limit
VOUT < 0.5 V
30
60
100
mA
IIN_MAX
Input Current Limit
1x mode, VOUT > 1 V
200
300
600
mA
IEN/DIM
VHI
VLO
EN/DIM Pin
− Input Leakage
− Logic High Level
− Logic Low Level
−1
1.3
1
0.4
mA
V
V
TSD
Thermal Shutdown
145
165
175
°C
THYS
Thermal Hysteresis
10
20
30
°C
Undervoltage lock out (UVLO) threshold
1.7
2
2.4
V
VUVLO
Table 4. RECOMMENDED EN/DIM TIMING (For 3 V ≤ VIN ≤ 5.5 V, over full ambient temperature range −40 to +85°C.)
Symbol
TSETP
Parameter
Conditions
Min
Typ
Max
Unit
EN/DIM setup from shutdown
10
TLO
EN/DIM program low time
0.3
THI
EN/DIM program high time
0.3
ms
EN/DIM low time to shutdown
1.5
ms
TOFF
TD
TDEC
ms
200
ms
LED current enable
40
ms
LED current decrement
0.1
ms
TSETP
THI
TOFF
EN/DIM
TD
TLO
TDEC
31 mA 30 mA
29 mA
31 mA
LED
Current
1 mA
Shutdown
0 mA
Figure 2. LED Dimming Timing Diagram
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3
Shutdown
CAT3614
TYPICAL CHARACTERISTICS
(VIN = 3.6 V, IOUT = 80 mA (4 LEDs at 20 mA), C1 = C2 = CIN = COUT = 1 mF, TAMB = 25°C unless otherwise specified.)
100
100
20 mA per LED
90
90
EFFICIENCY (%)
EFFICIENCY (%)
1x mode
80
70
10 mA per LED
60
50
40
4.0
3.8
3.6
3.4
3.2
0
25
50
75
100
Figure 3. Efficiency vs. Input Voltage (4 LEDs)
Figure 4. Efficiency vs. Total LED Current
(4 LEDs)
125
0.8
QUIESCENT CURRENT (mA)
QUIESCENT CURRENT (mA)
VIN = 3.2 V (1.5x Mode)
TOTAL LED CURRENT (mA)
0.4
4 LEDs OFF
0.2
3.0
3.2
3.4
3.6
3.8
4.0
0.6
0.4
4 LEDs OFF
0.2
0
−40
4.2
0
40
80
120
INPUT VOLTAGE (V)
TEMPERATURE (°C)
Figure 5. Quiescent Current vs. Input Voltage
(1x Mode)
Figure 6. Quiescent Current vs. Temperature
(1x Mode)
6
QUIESCENT CURRENT (mA)
6
QUIESCENT CURRENT (mA)
60
INPUT VOLTAGE (V)
0.6
5
4
3
2
4 LEDs OFF
1
0
70
40
3.0
0.8
0
80
50
1.5x mode
4.2
VIN = 4 V (1x Mode)
3.0
3.2
3.4
3.6
3.8
4.0
5
4
3
2
4 LEDs OFF
1
0
−40
4.2
0
40
80
120
INPUT VOLTAGE (V)
TEMPERATURE (°C)
Figure 7. Quiescent Current vs. Input Voltage
(1.5x Mode)
Figure 8. Quiescent Current vs. Temperature
(1.5x Mode)
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CAT3614
TYPICAL CHARACTERISTICS
5
4
4
3
1x Mode
2
1
0
−1
1.5x Mode
−2
−3
−4
−5
CLOCK FREQUENCY (MHz)
LED CURRENT CHANGE (%)
5
3.0
3.2
3.4
3.6
3.8
4.0
2
1
0
−1
−2
−3
−4
4.2
20
40
60
Figure 9. LED Current Change vs. Input
Voltage
Figure 10. LED Current Change vs.
Temperature
1.2
1.2
1.1
1.0
4 LEDs at 20 mA
0.9
0.8
3.2
3.4
3.6
3.8
80
1.1
1.0
0.9
0.8
0.7
−40
4.0
0
40
80
120
INPUT VOLTAGE (V)
TEMPERATURE (°C)
Figure 11. Oscillator Frequency vs. Input
Voltage
Figure 12. Oscillator Frequency vs.
Temperature
4.0
OUTPUT RESISTANCE (W)
1.0
0.8
0.6
0.4
0.2
0
0
TEMPERATURE (°C)
1.3
3.0
−20
INPUT VOLTAGE (V)
1.3
0.7
OUTPUT RESISTANCE (W)
3
−5
−40
CLOCK FREQUENCY (MHz)
LED CURRENT CHANGE (%)
(VIN = 3.6 V, IOUT = 80 mA (4 LEDs at 20 mA), C1 = C2 = CIN = COUT = 1 mF, TAMB = 25°C unless otherwise specified.)
3.0
3.2
3.4
3.6
3.8
4.0
3.5
3.0
2.5
2.0
1.5
1.0
4.2
3.0
3.2
3.4
3.6
3.8
4.0
4.2
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Figure 13. Output Resistance vs. Input Voltage
(1x Mode)
Figure 14. Output Resistance vs. Input Voltage
(1.5x Mode)
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CAT3614
TYPICAL CHARACTERISTICS
(VIN = 3.6 V, IOUT = 80 mA (4 LEDs at 20 mA), C1 = C2 = CIN = COUT = 1 mF, TAMB = 25°C unless otherwise specified.)
Figure 15. Power Up with 4 LEDs at 15 mA
(1x Mode)
Figure 16. Power Up with 4 LEDs at 15 mA
(1.5x Mode)
Figure 17. Enable Power Down Delay
(1x Mode)
Figure 18. Enable Power Down Delay
(1.5x Mode)
Figure 19. Switching Waveforms in 1.5x Mode
Figure 20. Operating Waveforms in 1x Mode
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CAT3614
TYPICAL CHARACTERISTICS
(VIN = 3.6 V, IOUT = 80 mA (4 LEDs at 20 mA), C1 = C2 = CIN = COUT = 1 mF, TAMB = 25°C unless otherwise specified.)
Figure 21. Enable and Output Current
Dimming Waveforms
Figure 22. Line Transient Response
(3.6 V to 5.5 V) 1x Mode
200
200
VIN = 3.5 V
160
VIN = 3.5 V
MINIMUM TIME (nS)
MINIMUM TIME (nS)
160
120
80
VIN = 4.2 V
40
0
−40
0
40
80
0
−40
120
0
40
80
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 23. Enable High Minimum Program
Time vs. Temperature
Figure 24. Enable Low Minimum Program
Time vs. Temperature
120
4.0
3.5
OUTPUT VOLTAGE (V)
1.0
ENABLE VOLTAGE (V)
VIN = 4.2 V
80
40
1.2
0.8
0.6
0.4
0.2
0
−40
120
3.0
1x Mode
2.5
VIN = 3.5 V
2.0
1.5
1.0
0.5
0
40
80
0
120
0
100
200
300
TEMPERATURE (°C)
OUTPUT CURRENT (mA)
Figure 25. Enable Voltage Threshold vs.
Temperature
Figure 26. Foldback Current Limit
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400
CAT3614
Table 5. PIN DESCRIPTIONS
Pin #
Name
Function
1
VIN
Supply voltage.
2
C1+
Bucket capacitor 1 terminal
3
C1−
Bucket capacitor 1 terminal
4
C2−
Bucket capacitor 2 terminal
5
C2+
Bucket capacitor 2 terminal
6
GND
Ground reference
7
LED1
LED1 cathode terminal (if not used, connect to VOUT) (Note 3)
8
LED2
LED2 cathode terminal (if not used, connect to VOUT) (Note 3)
9
LED3
LED3 cathode terminal (if not used, connect to VOUT) (Note 3)
10
LED4
LED4 cathode terminal (if not used, connect to VOUT) (Note 3)
11
EN/DIM
12
VOUT
TAB
TAB
Device enable (active high) and dimming control input
Charge pump output connected to the LED anodes
Connect to GND on the PCB
3. LED1, LED2, LED3, LED4 pins should not be left floating. They should be connected to the LED cathode, or tied to VOUT pin if not used.
Pin Function
VIN is the supply pin for the charge pump. A small 1 mF
ceramic bypass capacitor is required between the VIN pin
and ground near the device. The operating input voltage
range is from 2.2 V to 5.5 V. Whenever the input supply falls
below the undervoltage threshold (2 V) all LEDs channels
will be automatically disabled.
EN/DIM is the enable and dimming control logic input for
all LED channels. Guaranteed levels of logic high and logic
low are set at 1.3 V and 0.4 V respectively. When EN/DIM
is initially taken high, the device becomes enabled and all
LED currents remain at 0 mA. The falling edge of the first
pulse applied to EN/DIM sets all LED currents to their full
scale of 31 mA.
On each consecutive falling edge of the pulse applied to
EN/DIM, the LED current is decreased by 1 mA step. On the
32nd pulse, the LED current is set to zero. The next pulse on
EN/DIM resets the current back to their full scale of 31 mA.
To place the device into zero current shutdown mode, the
EN/DIM pin must be held low for 1.5 ms or more.
VOUT is the charge pump output that is connected to the
LED anodes. A small 1 mF ceramic bypass capacitor is
required between the VOUT pin and ground near the device.
GND is the ground reference for the charge pump. The pin
must be connected to the ground plane on the PCB.
C1+, C1− are connected to each side of the 1 mF ceramic
bucket capacitor C1.
C2+, C2− are connected to each side of the 1 mF ceramic
bucket capacitor C2.
LED1 to LED4 provide the internal regulated current for
each of the LED cathodes. These pins enter a high
impedance zero current state whenever the device is placed
in shutdown mode. In applications using less than four
LEDs, all unused channels should be wired directly to
VOUT. This ensures the channel is automatically disabled
dissipating less than 200 mA.
TAB is the exposed pad underneath the package. For best
thermal performance, the tab should be soldered to the PCB
and connected to the ground plane.
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CAT3614
Block Diagram
1 mF
C1−
C1+
VIN
1 mF
C2−
C2+
VOUT
1x mode (LDO)
1.5x Charge Pump
CIN
1 mF
1 MHz
Oscillator
EN/DIM
Mode Control
LED1
LED2
Reference
Voltage
LED3
LED4
Current
Setting DAC
LED Channel
Current Regulators
Serial
Interface
Registers
GND
Figure 27. CAT3614 Functional Block Diagram
Basic Operation
At power−up, the CAT3614 starts operating in 1x mode
where the output will be approximately equal to the input
supply voltage (less any internal voltage losses). If the
output voltage is sufficient to regulate all LED currents the
device remains in 1x operating mode.
If the input voltage is insufficient or falls to a level where
the regulated currents cannot be maintained, the device
automatically switches (after a fixed delay of 400 ms) into
1.5x mode.
In 1.5x mode, the output is approximately equal to 1.5
times the input supply voltage (less any internal voltage
losses).
The above sequence is repeated each and every time the
chip is powered−up or is taken out of shutdown mode (via
EN/DIM pin).
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CAT3614
LED Current Setting
temperature drops down by about 20°C, the device resumes
normal operation.
Figure 2 shows the timing diagram necessary at the
EN/DIM input for setting the LED currents.
The EN/DIM set up time requires the signal to be held
high for 10 ms or longer to ensure the initialization of the
driver at power−up. Each subsequent pulse on the EN/DIM
(300 ns to 200 ms pulse duration) steps down the LED
current from full scale of 31 mA to zero with a 1 mA
resolution. Consecutive pulses should be separated by
300 ns or longer. Pulsing beyond the 0 mA level restores the
current level back to full scale and the cycle repeats. Pulsing
frequencies from 5 kHz up to 1 MHz can be supported
during dimming operations. When the EN/DIM is held low
for 1.5 ms or more, the CAT3614 enters the shutdown mode
and draws “zero” current.
For applications with three LEDs or less, any unused LED
pins should be tied to VOUT, as shown on Figure 28.
External Components
The driver requires a total of four external 1 mF ceramic
capacitors: two for decoupling input and output, and two for
the charge pump. Both capacitor types X5R and X7R are
recommended for the LED driver application. In the 1.5x
charge pump mode, the input current ripple is kept very low
by design, and an input bypass capacitor of 1 mF is sufficient.
In 1x mode, the device operating in linear mode does not
introduce switching noise back onto the supply.
Recommended Layout
In 1.5x charge pump mode, the driver switches internally
at a high frequency of 1 MHz. It is recommended to
minimize trace length to all four capacitors. A ground plane
should cover the area under the driver IC as well as the
bypass capacitors. Short connection to ground on capacitors
Cin and Cout can be implemented with the use of multiple
vias. A copper area matching the TDFN exposed pad (GND)
must be connected to the ground plane underneath. The use
of multiple vias improves the package heat dissipation.
Protection Mode
If an LED becomes open−circuit, the output voltage
VOUT is internally limited to about 5.5 V. This is to prevent
the output pin from exceeding its absolute maximum rating.
The driver enters a thermal shutdown mode as soon as the
die temperature exceeds about +165°C. When the device
1 mF
VIN
3 V to
5.5 V
CIN
1 mF
ENABLE/
DIMMING
C1+
C1− C2+
VIN
1 mF
1 mF
C2−
VIN
VOUT
COUT
CAT3614
1 mF
LED1
LED2
EN/DIM
GND
LED3
LED4
3 V to
5.5 V
CIN
1 mF
ENABLE/
DIMMING
C1+
C1− C2+
C2−
VOUT
VIN
COUT
LED1
LED2
EN/DIM
LED3
LED4
Figure 29. Single Flash LED Application
EZDim is a trademark of Semiconductor Components Industries, LLC.
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Flash
LED
1 mF
CAT3614
GND
Figure 28. Three LED Application
1 mF
120 mA
MECHANICAL CASE OUTLINE
PACKAGE DIMENSIONS
TDFN12, 3x3
CASE 511AN−01
ISSUE A
D
DATE 18 MAR 2009
A
e
b
L
E
E2
PIN#1 ID
PIN#1 INDEX AREA
A1
TOP VIEW
BOTTOM VIEW
SIDE VIEW
SYMBOL
MIN
NOM
MAX
A
0.70
0.75
0.80
A1
0.00
0.02
0.05
A3
0.178
0.203
0.228
b
0.18
0.23
0.30
D
2.90
3.00
3.10
D2
2.30
2.40
2.50
E
2.90
3.00
3.10
E2
1.55
1.70
1.75
e
D2
A
A3
A1
FRONT VIEW
RECOMMENDED LAND PATTERN
R
e
M
0.45 BSC
L
0.30
0.40
0.50
M
0.25
0.30
0.35
N
0.60
0.70
0.80
P
2.70
3.00
3.10
R
2.25 TYP
N
P
E2
Notes:
(1) All dimensions are in millimeters.
(2) Complies with JEDEC MO-229.
D2
DOCUMENT NUMBER:
DESCRIPTION:
98AON34357E
TDFN12, 3X3
Electronic versions are uncontrolled except when accessed directly from the Document Repository.
Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red.
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