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CAT3644
4-Channel Ultra High Efficiency Quad-ModeTM LED Driver
FEATURES
High efficiency 1.33x charge pump Quad-mode charge pump: 1x, 1.33x, 1.5x, 2x Drives up to 4 LEDs at 25mA each 1-wire EZDimTM LED current programming 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 3mm x 3mm, 16-pad TQFN package
DESCRIPTION
The CAT3644 is a high efficiency Quad-ModeTM fractional charge pump that can drive up to four LEDs programmable by a one wire digital interface. The inclusion of a 1.33x fractional charge pump mode increases device efficiency by up to 10% over tradi- tional 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 2.5V to 5.5V. The EN/DIM logic input functions as a chip enable and a digital dimming interface for current setting of all LEDs. Six different current ratios are available via the interface. The device is available in the tiny 16-pad TQFN 3mm x 3mm package with a max height of 0.8mm.
TM Catalyst Semiconductor's Quad-Mode 1.33x charge pump switching architecture is patented.
APPLICATION
LCD Display Backlight Cellular Phones Digital Still Cameras Handheld Devices
ORDERING INFORMATION
Part Number CAT3644HV3-T2 CAT3644HV3-GT2 Qty per Reel 2000 2000 (2)
(1)
Marking JAAG JAAH For Ordering Information details, see page 13.
Notes: (1) Matte-Tin Plated Finish (RoHS-compliant) (2) NiPdAu Plated Finish (RoHS-compliant)
PIN CONFIGURATION
Top View
LED1 GND
TYPICAL APPLICATION CIRCUIT
1F 1F
NC
NC
C1+ CIN 1F EN/DIM RSET 4.02k GND VIN C1- C2+ C2VOUT VOUT COUT 1F LED1 LED2 LED3 LED4 20mA
16 LED2 LED3 LED4 RSET 1 2 3 4 5
EN/DIM
15
14
13 12 C211 C2+ 10 C19 C1+
VIN 2.4V to 5.5V
CAT3644
1-Wire EZDimTM Programming
6
VOUT
7
NC
8
VIN
(c) Catalyst Semiconductor, Inc. Characteristics subject to change without notice
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Doc. No. MD-5023, Rev. E
CAT3644
ABSOLUTE MAXIMUM RATINGS Parameter VIN, LEDx, C1, C2, EN/DIM voltage VOUT voltage Storage Temperature Range Junction Temperature Range RECOMMENDED OPERATING CONDITIONS Parameter VIN Ambient Temperature Range ILED per LED pin LED Forward Voltage Range Rating 2.5 to 5.5 -40 to +85 up to 30 1.3 to 4.3 Unit V C mA V Rating 6 7 -65 to +160 -40 to +150 Unit V V C C
Typical application circuit with external components is shown on page 1. ELECTRICAL OPERATING CHARACTERISTICS (over recommended operating conditions unless specified otherwise) VIN = 3.6V, EN = High, TAMB = 25C Symbol IQ IQSHDN ILED-ACC ILED-DEV VRSET ROUT FOSC ISC_MAX IIN_MAX LEDTH VHYS TDF REN/DIM VHI VLO TSD THYS VUVLO Name Quiescent Current Shutdown Current LED Current Accuracy LED Channel Matching RSET Regulated Voltage Output Resistance (open loop) Charge Pump Frequency Output short circuit Current Limit Input Current Limit 1x to 1.33x or 1.33x to 1.5x or 1.5x to 2x Transition Thresholds at any LED pin 1x Mode Transition Hysteresis Transition Filter Delay EN/DIM Pin * Internal Pull-down Resistor * Logic High Level * Logic Low Level Thermal Shutdown Thermal Hysteresis Undervoltage lockout (UVLO) threshold 1.6 1x mode 1.33x mode, VIN = 3V 1.5x mode, VIN = 2.7V 2x mode, VIN = 2.4V 1.33x and 2x mode 1.5x mode VOUT < 0.5V VOUT > 1V Conditions 1x mode, no load 1.33 x mode, no load 1.5x mode, no load 2x mode, no load VEN = 0V (ILEDAVG - INOMINAL) / INOMINAL RSET = 5k (ILED - ILEDAVG) / ILEDAVG 0.58 Min Typ 1.0 1.7 2.2 2.4 2 1.5 0.6 0.8 5 5 10 1 1.3 50 250 130 400 500 100 1.3 0.4 150 20 1.8 2.0 0.62 Max Units mA mA mA mA A % % V MHz MHz mA mA mV mV s k V V C C V
1
0.8 1
1.3 1.6
Doc. No. MD-5023, Rev. E
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(c) Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3644
RECOMMENDED EN/DIM TIMING For 2.4V VIN 5.5V, over full ambient temperature range -40C to +85C. Symbol TSETUP TLO THI TPWRDWN TLED Name EN/DIM setup from shutdown EN/DIM program low time EN/DIM program high time EN/DIM low time to shutdown LED current settling time Conditions Min 10 0.2 0.2 1.5 40 100 Typ Max Units s s s ms s
TSETUP
THI
TPWRDWN
EN/DIM TLED 100% 50% LED Current Shutdown 25% TLO 100%
12.5% 6.25% 3.12%
Shutdown
Figure 1. EN/DIM Digital Dimming Timing Diagram
LED Current Setting The nominal LED current is set by the external resistor connected between the RSET pin and ground. Table 1 lists standard resistor values for several LED current settings.
LED current (mA) 2 5 10 15 20 25 30
RSET (k) 40.0 15.8 7.87 5.23 4.02 3.16 2.67
Table 1. Resistor RSET and LED current
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Doc. No. MD-5023, Rev. E
CAT3644
TYPICAL PERFORMANCE CHARACTERISTICS VIN = 3.6V, IOUT = 80mA (4 LEDs at 20mA), CIN = COUT = C1 = C2 = 1F, TAMB = 25C unless otherwise specified. Efficiency vs. Input Voltage
100 90 EFFICIENCY [%] 1x 80 70 60 50 40 4.5 4.0 3.5 3.0 2.5 INPUT VOLTAGE [V] 2.0 2x VF = 3.3V 1.33x 1.5x
EFFICIENCY [%] 100 90 80 70 60 50 40 4.2 4.0 3.8 3.6 3.4 3.2 INPUT VOLTAGE [V] 3.0
Efficiency vs. Li-Ion Voltage
VF = 3.3V 1x 1.33x
Quiescent Current vs. Input Voltage
4.0 QUIESCENT CURRENT [mA]
QUIESCENT CURRENT [mA]
Quiescent Current vs. Temperature
4.0
VF = 3.3V 3.0 2.0 1.0 LEDs Off 0.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 INPUT VOLTAGE [V]
2x 3.0
1.5x
2.0
1.33x 1x
1.0
0.0 -40 0 40 80 TEMPERATURE [C] 120
LED Current Change vs. Input Voltage
10 8 6 4 2 0 -2 -4 -6 -8 -10 LED CURRENT VARIATION [%] .
LED CURRENT VARIATION [%] .
LED Current Change vs. Temperature
10 8 6 4 2 0 -2 -4 -6 -8 -10 -40 0 40 80 TEMPERATURE [C] 120 VF = 3.3V
VF = 3.3V
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE [V]
Doc. No. MD-5023, Rev. E
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CAT3644
TYPICAL PERFORMANCE CHARACTERISTICS VIN = 3.6V, IOUT = 80mA (4 LEDs at 20mA), CIN = COUT = C1 = C2 = 1F, TAMB = 25C unless otherwise specified. Switching Frequency vs. Temperature
SWITCHING FREQUENCY [MHz] 1.3
OUTPUT RESISTANCE [] .
Output Resistance vs. Input Voltage
12
1.2 1.1 1.0 0.9 0.8 0.7 -40
1.5x Mode
10 8 6 4 2 0 1.5x
2x
1.33x
1.33x, 2x Mode
1x
0 40 80 TEMPERATURE [C]
120
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE [V]
Power Up in 1x Mode
Power Up in 1.33x Mode
Power Up in 1.5x Mode
Power Up in 2x Mode
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Doc. No. MD-5023, Rev. E
CAT3644
TYPICAL PERFORMANCE CHARACTERISTICS VIN = 3.6V, IOUT = 80mA (4 LEDs at 20mA), CIN = COUT = C1 = C2 = 1F, TAMB = 25C unless otherwise specified. Power Up Delay (1x Mode) Power Down Delay (1x Mode)
Operating Waveforms in 1x Mode
Switching Waveforms in 1.33x Mode
Switching Waveforms in 1.5x Mode
Switching Waveforms in 2x Mode
Doc. No. MD-5023, Rev. E
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CAT3644
TYPICAL PERFORMANCE CHARACTERISTICS VIN = 3.6V, IOUT = 80mA (4 LEDs at 20mA), CIN = COUT = C1 = C2 = 1F, TAMB = 25C unless otherwise specified. Foldback Current Limit
4.0 OUTPUT VOLTAGE [V] 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 100 200 300 OUTPUT CURRENT [mA] 400 1x Mode
LED Current vs. LED Pin Voltage
40
LED CURRENT [mA]
30
20
10
0 0 50 100 150 200 250 LED PIN VOLTAGE [mV] 300
Dimming Waveform
50 LED CURRENT [mA] 40 30 20 10 0 1
LED Current vs. RSET
10 RSET RESISTANCE [k]
100
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Doc. No. MD-5023, Rev. E
CAT3644 PIN DESCRIPTION
Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 TAB Name LED2 LED3 LED4 RSET EN/DIM VOUT NC VIN C1+ C1C2+ C2NC NC GND LED1 GND Function LED2 cathode terminal. LED3 cathode terminal. LED4 cathode terminal. Connect resistor RSET to set the LED current. Device enable (active high) and Dimming Control. Charge pump output connected to the LED anodes. Not connected inside the package. 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 Not connected inside the package. Not connected inside the package. Ground Reference LED1 cathode terminal. Connect to GND on the PCB.
PIN FUNCTION
VIN is the supply pin for the charge pump. A small 1F ceramic bypass capacitor is required between the VIN pin and ground near the device. The operating input voltage range is from 2.5V to 5.5V. Whenever the input supply falls below the under-voltage threshold (1.8V), all the LED channels are disabled and the device enters shutdown mode. EN/DIM is the enable and one wire dimming input for all LED channels. Levels of logic high and logic low are set at 1.3V and 0.4V respectively. When EN/DIM is initially taken high, the device becomes enabled and all LED currents are set to the full scale according to the resistor RSET. To place the device into "zero current" shutdown mode, the EN/DIM pin must be held low for at least 1.5ms. VOUT is the charge pump output that is connected to the LED anodes. A small 1F 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 LED4 provide the internal regulated current source 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. RSET is connected to the resistor (RSET) to set the full scale current for the LEDs. The voltage at this pin regulated to 0.6V. The ground side of the external resistor should be star connected back to the GND of the PCB. In shutdown mode, RSET beomes high impedance.
Doc. No. MD-5023, Rev. E
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(c) Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3644 BLOCK DIAGRAM
C1C1+ C2C2+
VIN
1x mode (LDO) 4/3x, 3/2x, 2x Charge Pump
VOUT
Mode Control EN/DIM 100k Serial Interface Reference Voltage 1, 1.3MHz Oscillator LED1 LED2 LED3 LED4
Registers
Current Setting DAC
LED Channel Current Regulators
RSET
GND
Figure 2. CAT3644 Functional Block Diagram
BASIC OPERATION
At power-up, the CAT3644 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 into 1.33x mode (after a fixed delay time of about 400s). In 1.33x mode, the output voltage is approximately equal to 1.33 times the input supply voltage (less any internal voltage losses). This sequence repeats in the 1.33x and 1.5x mode until the driver enters the 2x mode. In 1.5x mode, the output voltage is approximately equal to 1.5 times the input supply voltage. While in 2x mode, the output is approximately equal to 2 times the input supply voltage. If the device detects a sufficient input voltage is present to drive all LED currents in 1x mode, it will change automatically back to 1x mode. This only applies for changing back to the 1x mode. The difference between the input voltage when exiting 1x mode and returning to 1x mode is called the 1x mode transition hysteresis (VHYS) and is about 500mV.
(c) Catalyst Semiconductor, Inc. Characteristics subject to change without notice
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Doc. No. MD-5023, Rev. E
CAT3644
LED Current Selection At power-up, the initial LED current is set to full scale (100% brightness) by the external resistor RSET as follows: 0 .6 V LED current = 132 x R SET The EN/DIM pin has two primary functions. One function enables and disables the device. The other function is LED current dimming with six different
levels by pulsing the input signal, as shown on Figure 3. On each consecutive pulse rising edge, the LED current is divided by half to 50%, then 25%, 12.5%, 6.25% and 3.125% dimming levels. Pulses faster than the minimum TLO may be ignored and filtered by the device. Pulses longer than the maximum TLO may shutdown the device. The LED driver enters a "zero current" shutdown mode if EN/DIM is held low for 1.5ms or more.
TSETUP
THI
TPWRDWN
EN/DIM TLED 100% 50% LED Current Shutdown 25% TLO 100%
12.5% 6.25% 3.12%
Shutdown
Figure 3. EN/DIM Digital Dimming Timing Diagram Table 1. LED Current Dimming Levels EN/DIM # of pulses * EN = High 1 2 3
st nd rd th th th
RSET Gain 132 66 33 16.5 8.25 4.125 132 Device cycling through gain selection
LED Current
132 x 0.6 V R SET 66 x 0.6 V R SET 33 x 0.6 V R SET 16.5 x 0.6 V R SET 8.25 x 0.6 V R SET 4.125 x 0.6 V R SET 132 x 0.6 V R SET GAIN x 0.6 V R SET
4 5 6 x
th
* The gain is changed on the rising edges of the EN/DIM input.
Doc. No. MD-5023, Rev. E
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(c) Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3644
Unused LED Channels For applications not requiring all the channels, it is recommended the unused LED pins be tied directly to VOUT (see Figure 4).
1F 1F
External Components The driver requires four external 1F 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 1F is sufficient. In 1x mode, the device operates in linear mode and does not introduce switching noise back onto the supply. Recommended Layout 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.
GND
VIN CIN 1F ENABLE DIMMING
C1+ VIN
C1- C2+
C2VOUT COUT
CAT3644
LED1 EN/DIM RSET LED2 LED3 GND LED4
1F
RSET
Figure 4. Application with 3 LEDs Protection Mode If an LED is disconnected, the driver senses that and automatically ignores that channel. When all LEDs are disconnected, the driver goes to 1x mode where the output is equal to the input voltage. As soon as the output exceeds about 6V, the driver resets itself and reevaluate the mode. 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 1.3V to 4.3V may be used. 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 3.3V is selected over one with VF of 3.5V, the driver will stay in 1x mode for lower supply voltage of 0.2V. This helps improve the efficiency and extends battery life.
Pin1
C2
EN/DIM RSET
C1
VIN GND COUT CIN
GND
Figure 5. Recommended Layout
(c) Catalyst Semiconductor, Inc. Characteristics subject to change without notice
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Doc. No. MD-5023, Rev. E
CAT3644 PACKAGE OUTLINE DRAWING
TQFN 16-Pad 3 x 3mm (HS3, HV3) (1)(2)
D
A
e
b L
E
E2 PIN#1 ID
PIN#1 INDEX AREA TOP VIEW
A1 SIDE VIEW
D2 BOTTOM VIEW
SYMBOL
MIN
NOM
MAX
A A1 A3 b D D2 E E2 e L
0.70 0.00 0.178 0.18 2.90 1.40 2.90 1.40 0.30
0.75 0.02 0.203 0.23 3.00 - 3.00 - 0.50 BSC 0.40
0.80 0.05 0.228 0.30 3.10 1.80 3.10 1.80 0.50
A
A1 FRONT VIEW
A3
For current Tape and Reel information, download the PDF file from: http://www.catsemi.com/documents/tapeandreel.pdf.
Notes: (1) All dimensions are in millimeters. (2) Complies with JEDEC standard MO-229.
Doc. No. MD-5023, Rev. E
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(c) Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3644 EXAMPLE OF ORDERING INFORMATION
(1)
Prefix CAT
Device # 3644
Suffix HV3 -G T2
Product Number Optional Company ID Package HV3: TQFN
Lead Finish Blank: Matte-Tin G: NiPdAu Tape & Reel T: Tape & Reel 2: 2000/Reel
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 CAT3644HV3-GT2 (TQFN, NiPdAu, Tape & Reel). (4) For additional package and temperature options, please contact your nearest Catalyst Semiconductor Sales office.
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Doc. No. MD-5023, Rev. E
REVISION HISTORY
Date 01/29/2007 02/26/2007 06/15/2007 Rev. A B C Reason Initial Release Electrical Operating Characteristics - Add the pull-down resistor value 100k Block Diagram - Add a 100k pull-down resistor Updated Example of Ordering Information Added MD- to document number Added RSET in Absolute Maximum Ratings table Updated Recommended Operating Condition table Updated Electrical Operating Characteristics table Added LED Current section Updated Package Outline Drawing Update Description Update Absolute Maximum Ratings Update Updated Package Outline Drawing
07/25/2007
D
10/16/2007
E
Copyrights, Trademarks and Patents (c) Catalyst Semiconductor, Inc. Trademarks and registered trademarks of Catalyst Semiconductor include each of the following: Adaptive AnalogTM, Beyond MemoryTM, DPPTM, EZDimTM, LDDTM, MiniPotTM, Quad-ModeTM and Quantum Charge ProgrammableTM Catalyst Semiconductor has been issued U.S. and foreign patents and has patent applications pending that protect its products. CATALYST SEMICONDUCTOR MAKES NO WARRANTY, REPRESENTATION OR GUARANTEE, EXPRESS OR IMPLIED, REGARDING THE SUITABILITY OF ITS PRODUCTS FOR ANY PARTICULAR PURPOSE, NOR THAT THE USE OF ITS PRODUCTS WILL NOT INFRINGE ITS INTELLECTUAL PROPERTY RIGHTS OR THE RIGHTS OF THIRD PARTIES WITH RESPECT TO ANY PARTICULAR USE OR APPLICATION AND SPECIFICALLY DISCLAIMS ANY AND ALL LIABILITY ARISING OUT OF ANY SUCH USE OR APPLICATION, INCLUDING BUT NOT LIMITED TO, CONSEQUENTIAL OR INCIDENTAL DAMAGES. Catalyst Semiconductor 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 Catalyst Semiconductor product could create a situation where personal injury or death may occur. Catalyst Semiconductor reserves the right to make changes to or discontinue any product or service described herein without notice. Products with data sheets labeled "Advance Information" or "Preliminary" and other products described herein may not be in production or offered for sale. Catalyst Semiconductor advises customers to obtain the current version of the relevant product information before placing orders. Circuit diagrams illustrate typical semiconductor applications and may not be complete.
Catalyst Semiconductor, Inc. Corporate Headquarters 2975 Stender Way Santa Clara, CA 95054 Phone: 408.542.1000 Fax: 408.542.1200 www.catsemi.com
Document No: MD-5023 Revision: E Issue date: 10/16/07

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