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CAT3637 6-Channel Programmable High Efficiency Quad-Mode) LED Driver
Description
The CAT3637 is a high efficiency Quad-Mode fractional charge pump that can drive up to six LEDs programmable by a 1-wire digital interface. The inclusion of a 1.33x fractional charge pump mode increases device efficiency by up to 10% over traditional 1.5x charge pumps with no added external capacitors. Low noise input ripple is achieved by operating at a constant switching frequency which allows the use of small external ceramic capacitors. The multi-fractional charge pump supports a wide range of input voltages from 2.5 V to 5.5 V. The EN/SET logic input functions as a chip enable and a digital programming interface for setting the current in the LED channels. The 1-wire pulse-programming interface supports 15 linear steps from zero current to 30 mA full-brightness in 2 mA steps. The device is available in a tiny 16-pad TQFN 3 x 3 mm package with a maximum height of 0.8 mm. ON Semiconductor's Quad-Mode 1.33x, charge pump switching architecture is patented.
Features
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TQFN-16 HV3 SUFFIX CASE 510AD
PIN CONNECTIONS
EN/SET GND NC NC
LED6 LED5 LED4 LED3
1
C2- C2+ C1- C1+
* * * * * * * * * * * *
High Efficiency 1.33x Charge Pump Quad-Mode Charge Pump: 1x, 1.33x, 1.5x, 2x Drives 6 LEDs Between 30 mA and 0 mA Each 1-wire EZDimt Interface with 2 mA Step Power Efficiency up to 92% Low Noise Input Ripple in All Modes "Zero" Current Shutdown Mode Soft Start and Current Limiting Short Circuit Protection Thermal Shutdown Protection Tiny 3 mm x 3 mm, 16-pad TQFN Package These Devices are Pb-Free, Halogen Free/BFR Free and are RoHS Compliant LCD Display Backlight Cellular Phones Digital Still Cameras Handheld Devices
LED2
LED1
(Top View)
MARKING DIAGRAM
JAAM AXXX YWW JAAM = CAT3637HV3-GT2 A = Assembly Location XXX = Last Three Digits of Assembly Lot Number Y = Production Year (Last Digit) WW = Production Week (Two Digits)
Applications
* * * *
ORDERING INFORMATION
Device CAT3637HV3-GT2 (Note 1) Package TQFN-16 (Pb-Free) Shipping 2,000/ Tape & Reel
1. NiPdAu Plated Finish (RoHS-compliant).
(c) Semiconductor Components Industries, LLC, 2010
April, 2010 - Rev. 3
1
Publication Order Number: CAT3637/D
VOUT
VIN
CAT3637
1 mF VIN 2.5 V to 5.5 V CIN 1 mF 1 mF VOUT COUT 1 mF
C1- C1+ C2- C2+ VIN VOUT CAT3637 EN/SET GND LED1 LED2 LED3 LED4 LED5 LED6
1-Wire Programming
Figure 1. Typical Application Circuit Table 1. ABSOLUTE MAXIMUM RATINGS
Parameter VIN, LEDx, C1, C2 voltage VOUT Voltage EN/SET Voltage Storage Temperature Range Junction Temperature Range (Note 2) Lead Temperature Rating 6 7 VIN + 0.7 V -65 to +160 -40 to +150 300 Unit V V V _C _C _C
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 VIN Ambient Temperature Range (Note 2) ILED per LED pin Total Output Current 2. Package thermal resistance is below 50C/W when mounted on FR4 board. Range 2.5 to 5.5 -40 to +85 0 to 30 0 to 180 Unit V _C mA mA
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Table 3. ELECTRICAL OPERATING CHARACTERISTICS
(over recommended operating conditions unless specified otherwise) VIN = 3.6 V, EN = High, TAMB = 25C Symbol IQ Quiescent Current Name Conditions 1x mode, VIN = 4.2 V 1.33x mode, VIN = 3.3 V 1.5x mode, VIN = 2.8 V 2x mode, VIN = 2.5 V VEN = 0 V 2 mA ILED 30 mA I LED * I LEDAVG I LEDAVG 1x mode, IOUT = 120 mA 1.33x mode, IOUT = 120 mA 1.5x mode, IOUT = 120 mA 2x mode, IOUT = 120 mA 1.33x and 2x mode 1.5x mode VOUT < 0.5 V 0.6 0.8 3 1 0.5 3.5 3.5 6 0.8 1.1 80 150 VIN - Highest LED VF VOUT > 1 V 400 120 450 100 1.3 0.4 150 20 2 1.1 1.4 Min Typ 1.5 2.8 3.7 3.8 1 Max Units mA
IQSHDN ILED-ACC ILED-DEV ROUT
Shutdown Current LED Current Accuracy LED Channel Matching
mA % %
Output Resistance (open loop)
W
FOSC ISC_MAX LEDTH VHYS TDF IIN_MAX REN/DIM VHI VLO TSD THYS VUVLO NOTE:
Charge Pump Frequency Output short circuit Current Limit 1x to 1.33x or 1.33x to 1.5x or 1.5x to 2x Transition Thresholds at any LEDx pin 1.33x to 1x Transition Hysteresis Mode Transition Filter Delay Input Current Limit EN/DIM Pin - Internal Pull-down Resistor - Logic High Level - Logic Low Level Thermal Shutdown Thermal Hysteresis Undervoltage lockout (UVLO) threshold
MHz mA mV mV ms mA kW V V C C V
Typical application circuit with external components is shown on page 2.
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CAT3637
Table 4. RECOMMENDED EN/SET TIMING (For 2.5 VIN 5.5 V, over full ambient temperature range -40 to +85C.)
Symbol TLO THI TOFF TD Name EN/SET program low time EN/SET program high time EN/SET low time to shutdown LED current settling time THI Conditions Min 0.2 0.2 1.5 10 Typ Max 100 Units ms ms ms ms
EN/SET
TLO TD LED Current Shutdown 0 mA 28 mA 6 mA 0 mA 30 mA
TOFF
2 mA 4 mA
2 mA
Shutdown
Figure 2. EN/SET One Wire Addressable Timing Diagram
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CAT3637
TYPICAL PERFORMANCE CHARACTERISTICS
(VIN = 3.6 V, IOUT = 120 mA (6 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25C unless otherwise specified.) 100 VF = 3.3 V 90 EFFICIENCY (%) 1x 80 70 60 50 40 1.33x 1.5x EFFICIENCY (%) 2x 90 80 70 60 50 40 Traditional 1.5x Charge Pump 4.2 4.0 3.8 3.6 3.4 3.2 3.0 100 VF = 3.3 V VF = 3.0 V
4.5
4.0
3.5
3.0
2.5
2.0
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Figure 3. Efficiency vs. Input Voltage
10 LED CURRENT VARIATION (%) 6 4 2 0 -2 -4 -6 -8 -10 LED CURRENT VARIATION (%) 8 VF = 3.3 V 10 8 6 4 2 0 -2 -4 -6 -8 -10 -40
Figure 4. Efficiency vs. Li-Ion Voltage
5.5
5.0
4.5
4.0
3.5
3.0
2.5
-20
0
20
40
60
80
INPUT VOLTAGE (V)
TEMPERATURE (C)
Figure 5. LED Current Change vs. Input Voltage
6 QUIESCENT CURRENT (mA) VF = 3.3 V 5 4 3 2 1 0 5.5 5.0 4.5 4.0 3.5 3.0
Figure 6. LED Current Change vs. Temperature
2.5
2.0
INPUT VOLTAGE (V)
Figure 7. Quiescent Current vs. Input Voltage
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CAT3637
TYPICAL PERFORMANCE CHARACTERISTICS
(VIN = 3.6 V, IOUT = 120 mA (6 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25C unless otherwise specified.) 1.2 SWITCHING FREQUENCY (MHz) OUTPUT RESISTANCE (W) 1.1 1.0 0.9 0.8 0.7 0.6 -40 1.33x, 2x Mode 1.5x Mode 10 VF = 3.3 V 8 6 1.33x 4 2 0 2x 1.5x
1x 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0
-20
0
20
40
60
80
TEMPERATURE (C)
INPUT VOLTAGE (V)
Figure 8. Switching Frequency vs. Temperature
Figure 9. Output Resistance vs. Input Voltage
Figure 10. Power Up in 1x Mode
Figure 11. Power Up in 1.33x Mode
Figure 12. Power Up in 1.5x Mode
Figure 13. Power Up in 2x Mode
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CAT3637
TYPICAL PERFORMANCE CHARACTERISTICS
(VIN = 3.6 V, IOUT = 120 mA (6 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25C unless otherwise specified.)
Figure 14. Power Up Delay (1x Mode)
Figure 15. Power Down Delay (1x Mode)
Figure 16. Operating Waveforms in 1x Mode
Figure 17. Switching Waveforms in 1.33x Mode
Figure 18. Switching Waveforms in 1.5x Mode
Figure 19. Switching Waveforms in 2x Mode
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CAT3637
TYPICAL PERFORMANCE CHARACTERISTICS
(VIN = 3.6 V, IOUT = 120 mA (6 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25C unless otherwise specified.) 4.0 3.5 OUTPUT VOLTAGE (V) 3.0 2.5 2.0 1.5 1.0 0.5 0 0 100 200 300 400 500 1x Mode
OUTPUT CURRENT (mA)
Figure 20. Foldback Current Limit
Figure 21. LED Brightness Levels
Figure 22. LED Settling Time
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CAT3637
Table 5. PIN DESCRIPTION
Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13/14 15 16 TAB Name LED6 LED5 LED4 LED3 LED2 LED1 VOUT VIN C1+ C1- C2+ C2- NC GND EN/SET TAB LED6 cathode terminal LED5 cathode terminal LED4 cathode terminal LED3 cathode terminal LED2 cathode terminal LED1 cathode terminal Charge pump output, connect to LED anodes Charge pump input, connect to battery or supply Bucket capacitor 1, positive terminal Bucket capacitor 1, negative terminal Bucket capacitor 2, positive terminal Bucket capacitor 2, negative terminal No connect Ground reference Device enable (active high) and 1 wire control input Connect to GND on the PCB Function
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 2.5 V to 5.5 V. Whenever the input supply falls below the under-voltage threshold (2 V) all the LED channels will be automatically disabled and the device register are reset to default values. EN/SET is the enable and one wire addressable 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/SET is initially taken high, the device becomes enabled and all LED currents remain at 0 mA. To place the device into zero current mode, the EN/SET pin must be held low for more than 1.5 ms. 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 ceramic bucket capacitor C1. C2+, C2- are connected to each side of the ceramic bucket capacitor C2. LED1 to LED6 provide the internal regulated current for each of the LED cathodes. These pins enter high-impedance zero current state whenever the device is placed in shutdown mode. 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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CAT3637
Simplified Block Diagram
C1- C1+ C2- C2+
VIN
1x mode (LDO) 1.33x, 1.5x, 2x Charge Pump
VOUT
EN/SET 100 k Serial Interface
0.8, 1.1 MHz Oscillator
Mode Control LED1 LED2 LED3 LED4 LED5 LED6
Reference Voltage
Registers
Current Setting DAC
6 Current Regulators
GND
Figure 23. CAT3637 Functional Block Diagram
Basic Operation At power-up, the CAT3637 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 output voltage is insufficient or falls to a level where the regulated current cannot be maintained, the device automatically switches into 1.33x mode (after a fixed delay time of about 120 ms). In 1.33x mode, the output voltage is approximately equal to 1.33 times the input supply voltage (less any internal voltage losses). If the output voltage is still insufficient or falls to a level where the regulated currents cannot be maintained, the
device will automatically switch to the 1.5x mode (after a fixed delay time of about 400 ms). In 1.5x mode, the output is approximately equal to 1.5 times the input supply voltage (less any internal voltage losses). If the output voltage is still insufficient to drive the LEDs, it will automatically switch into 2x mode where the output is approximately equal to 2 times the input supply voltage (less any internal voltage losses). If the device detects a sufficient output voltage to drive all LED currents in 1x mode, it will revert back to 1x mode. This only applies for changing back to the 1x mode.
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CAT3637
LED Current Setting
The current in each of the six LED channels is programmed through the 1-wire EN/SET digital control input. At the initial power-up and once the EN/SET is set high, the LED current remains at zero in all channels. On the first EN/SET pulse (positive edge), the current is set to 2 mA in all channels. On each consecutive pulse, the current is incremented by 2 mA. On the 15th pulse, the current is equal to the full scale of 30 mA. On the following pulse (16th pulse), the current goes back to zero and the previous
THI EN/SET
sequence can be repeated. The EN/SET pin can be pulsed at high frequency 15 times to decrement the current by 2 mA or to program the current from 0 mA to 30 mA. The maximum EN/SET signal frequency for programming the LED current is 2.5 MHz. To power-down the device and turn-off all current sources, the EN/SET input should be kept low for a duration TOFF of 1.5 ms or more. The driver typically powers-down with a delay of about 1 ms.
TLO TD LED Current Shutdown 0 mA 28 mA 30 mA 6 mA
TOFF
2 mA 4 mA
0 mA
2 mA
Shutdown
Figure 24. EN/SET One Wire Addressable Timing Diagram
Figure 25. EN/SET Program Increasing / Decreasing LED Current by 2 mA
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CAT3637
Unused LED Channels
For applications with 5 LEDs or less, unused LEDs can be disabled by connecting the LED pin directly to VOUT, as shown on Figure 26. If LED pin voltage is within 1 V of
1 mF VIN CIN 1 mF 1 mF
VOUT, then the channel is switched off and a 200 mA test current is placed in the channel to sense when the channel moves below VOUT - 1 V.
2.5 V to 5.5 V
C1- C1+ C2- C2+ VIN VOUT CAT3637 EN/SET GND LED1 LED2 LED3 LED4 LED5 LED6
VOUT COUT 1 mF
1-Wire Programming
Figure 26. Five LED Application Protection Mode Recommended Layout
If an LED is disconnected, the output voltage VOUT automatically limits at about 5.5 V. This is to prevent the output pin from exceeding its absolute maximum rating. If the die temperature exceeds +150C the driver will enter a thermal protection shutdown mode. When the device temperature drops by about 20C the device will resume normal operation.
LED Selection
LEDs with forward voltages (VF) ranging from 1.3 V to 5.0 V may be used with the CAT3637. Selecting LEDs with lower VF is recommended in order to improve the efficiency by keeping the driver in 1x mode longer as the battery voltage decreases. For example, if a white LED with a VF of 3.3 V is selected over one with VF of 3.5 V, the CAT3637 will stay in 1x mode for lower supply voltage of 0.2 V. This helps improve the efficiency and extends battery life.
External Components
In charge pump mode, the driver switches internally at a high frequency. 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 via. A copper area matching the TQFN exposed pad (TAB) must be connected to the ground plane underneath. The use of multiple via improves the package heat dissipation.
The driver requires two external 1 mF ceramic capacitors for decoupling input, output, and for the charge pump. Both capacitors type X5R and X7R are recommended for the LED driver application. In all charge pump modes, 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 operates in linear mode and does not introduce switching noise back onto the supply.
Figure 27. Recommended Layout
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CAT3637
PACKAGE DIMENSIONS
TQFN16, 3x3 CASE 510AD-01 ISSUE A
D A e b L
E
E2
PIN#1 ID
PIN#1 INDEX AREA TOP VIEW
A1 SIDE VIEW
D2 BOTTOM VIEW
SYMBOL A A1 A3 b D D2 E E2 e L
MIN 0.70 0.00 0.18 2.90 1.40 2.90 1.40 0.30
NOM 0.75 0.02 0.20 REF 0.25 3.00 --- 3.00 --- 0.50 BSC 0.40
MAX 0.80 0.05 0.30 3.10 1.80 3.10 1.80 0.50 A1 FRONT VIEW A3
A
Notes: (1) All dimensions are in millimeters. (2) Complies with JEDEC MO-220.
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CAT3637
Example of Ordering Information (Note 5)
Prefix CAT Device # 3637 Suffix HV3 -G T2
Company ID (Optional)
Product Number 3637
Package HV3: TQFN 3 x 3 mm
Lead Finish G: NiPdAu
Tape & Reel (Note 7) T: Tape & Reel 2: 2,000 / Reel
3. 4. 5. 6. 7.
All packages are RoHS-compliant (Lead-free, Halogen-free). The standard lead finish is NiPdAu. The device used in the above example is a CAT3637HV3-GT2 (TQFN, NiPdAu, Tape & Reel, 2,000/Reel). For additional package and 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.
EZDim is a trademark of Semiconductor Components Industries, LLC. Quad-Mode is a registered trademark of Semiconductor Components Industries, LLC.
ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). 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: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303-675-2175 or 800-344-3860 Toll Free USA/Canada Fax: 303-675-2176 or 800-344-3867 Toll Free USA/Canada Email: orderlit@onsemi.com N. American Technical Support: 800-282-9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81-3-5773-3850 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative
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CAT3637/D

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