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CAT3648
4-Channel Ultra High Efficiency Quad-Mode(R) LED Driver with 32 Dimming Levels
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 32 linear steps 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 CAT3648 is a high efficiency quad-mode 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 setting the current in all LED channels. The 1-wire pulse-dimming interface supports 32 linear steps from full-scale down to zero current. The device is available in the tiny 16-pad TQFN 3mm x 3mm package with a max height of 0.8mm.
(R) 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 CAT3648HV3-GT2 Qty per Reel 2000
(1)
Marking JAAN
Notes: (1) NiPdAu Plated Finish (RoHS-compliant)
PIN CONFIGURATION
(Top View)
TYPICAL APPLICATION CIRCUIT
1F 1F
VIN 2.4V to 5.5V CIN 1F
C1+ VIN
C1- C2+
C2VOUT VOUT COUT
CAT3648
LED1 EN/DIM RSET LED2 LED3 GND LED4
1F
1-Wire EZDimTM Programming 3.74k
20mA
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
1
Doc. No. MD-5031, Rev. C
CAT3648
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-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 Setting 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 Mode Transition Filter Delay EN/DIM Pin * Internal Pull-down Resistor * Logic High Level * Logic Low Level Thermal Shutdown Thermal Hysteresis Undervoltage lockout (UVLO) threshold
Conditions
1x mode, excluding load 1.33 x mode, excluding load 1.5x mode, excluding load 2x mode, excluding load VEN = 0V RSET = 3.74k RSET = 7.50k (ILEDAVG - INOMINAL) / INOMINAL RSET = 4.99k (ILED - ILEDAVG) / ILEDAVG
Min
Typ
1.0 1.7 2.2 2.4
Max
Units
mA mA mA mA
1 20 10 2 1.5 0.58 0.6 0.8 5 5 10 1 1.3 50 250 130 400 120 100 1.3 0.4 150 20 1.6 1.8 2.0 0.62
A mA % % V MHz MHz mA mA mV mV s k V V C C V
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, 1x mode
0.8 1
1.3 1.6
Doc. No. MD-5031, Rev. C
2
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
CAT3648
RECOMMENDED EN/DIM TIMING For 2.4V VIN 5.5V, over full ambient temperature range -40C to +85C. Symbol TLO THI TPWRDWN TLED Name EN/DIM program low time EN/DIM program high time EN/DIM low time to shutdown LED current settling time Conditions Min 0.2 0.2 1.5 40 Typ Max 100 Units s s ms s
THI EN/DIM TLO TLED 100% LED Current 97% 94% 32 Levels 3% 100%
TPWRDWN
Shutdown
0%
Shutdown
Figure 1. EN/DIM Digital Dimming Timing Diagram
LED Current Setting The full scale 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.
Table 1. Resistor RSET and LED Current
Full Scale LED Current [mA] 2 5 10 15 20 25 30 RSET [k] 37.4 14.7 7.50 4.99 3.74 3.00 2.49
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
3
Doc. No. MD-5031, Rev. C
CAT3648
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-5031, Rev. C
4
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
CAT3648
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 1.2 1.1 1.0 0.9 0.8 0.7 -40 0 40 80 TEMPERATURE [C] 120 1.33x, 2x Mode
OUTPUT RESISTANCE [] .
Output Resistance vs. Input Voltage
12
1.5x Mode
10 8 6 4 2 0 1.5x
2x
1.33x
1x
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
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
5
Doc. No. MD-5031, Rev. C
CAT3648
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-5031, Rev. C
6
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
CAT3648
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
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
7
Doc. No. MD-5031, Rev. C
CAT3648 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 becomes high impedance.
Doc. No. MD-5031, Rev. C
8
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
CAT3648 BLOCK DIAGRAM
C1+ C1C2C2+
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. CAT3648 Functional Block Diagram
BASIC OPERATION
At power-up, the CAT3648 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 120s). 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 400mV.
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
9
Doc. No. MD-5031, Rev. C
CAT3648
LED Current Selection Table 2. Dimming Levels Full Scale Current in %
100 97 94 90 87 84 81 77 74 71 68 65 61 58 55 52 48 45 42 39 35 32 29 26 23 19 16 13 10 6 3 0 100
After power-up, the LED current is set by the external resistor (RSET) value and the number of pulses (n) on the EN/DIM input as follows: LED current = 125 x 0.6V 31 - n x R SET 31
Dimming Pulses [n]
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
The full scale current is calculated from the above formula with n equal to zero. The EN/DIM pin has two primary functions. One function enables and disables the device. The other function is LED current dimming with 32 different levels by pulsing the input signal, as shown on Figure 3. On each consecutive pulse rising edge, the LED current is decreased by about 3.2% (1/31th of the full scale value). After 30 pulses, the LED current is 3.2% of the full scale current. On the 31st pulse, the current drops to zero, and then goes back to full scale on the following pulse. Each pulse width should be between 200ns and 100s. Pulses faster than the minimum TLO may be ignored and filtered by the device. Pulses longer than the maximum TLO may shutdown the device. By pulsing the EN/DIM signal at high frequency, the LED current can quickly be set to zero. The LED driver enters a "zero current" shutdown mode if EN/DIM is held low for 1.5ms or more. The dimming level is set by the number of pulses on the EN/DIM after the power-up, as shown in Table 2.
THI EN/DIM TLO TLED 100% LED Current 97% 94% 32 Levels 3% 100%
TPWRDWN
Shutdown
0%
Shutdown
Figure 3. EN/DIM Digital Dimming Timing Diagram
Doc. No. MD-5031, Rev. C
10
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
CAT3648
Unused LED Channels External Components
For applications not requiring all the channels, it is recommended the unused LED pins be tied directly to VOUT (see Figure 4).
1F 1F
VIN CIN 1F ENABLE DIMMING
C1+ VIN
C1- C2+
C2VOUT COUT
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
CAT3648
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 re-evaluates 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
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
Pin1
C2
EN/DIM RSET
C1
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.
VIN GND COUT CIN
GND
Figure 5. Recommended Layout
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
11
Doc. No. MD-5031, Rev. C
CAT3648 PACKAGE OUTLINE DRAWING
TQFN 16-Pad 3 x 3mm (HS3, HV3)
(1)(2)
0F
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 0.18 2.90 1.40 2.90 1.40 0.30
0.75 0.02 0.20 REF 0.25 3.00 - 3.00 - 0.50 BSC 0.40
0.80 0.05
A
A1
A3 FRONT VIEW
0.30 3.10 1.80 3.10 1.80 0.50
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-220.
Doc. No. MD-5031, Rev. C
12
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
CAT3648 EXAMPLE OF ORDERING INFORMATION
Prefix Device # Suffix
(1)(2)
1F
CAT
3648
HV3
-G
T2
Product Number Optional Company ID Package HV3: TQFN
Lead Finish G: NiPdAu Tape & Reel T: Tape & Reel 2: 2,000/Reel
Notes: (1) All packages are RoHS-compliant (Lead-free, Halogen-free). (2) (3) (4) The standard lead finish is NiPdAu. The device used in the above example is a CAT3648HV3-GT2 (TQFN, NiPdAu, Tape & Reel, 2,000/Reel). For additional package and temperature options, please contact your nearest ON Semiconductor Sales office. 13
Doc. No. MD-5031, Rev. C
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice
CAT3648 REVISION HISTORY
Date 02-Apr-08 Revision A Description Initial Release
07-Aug-08 17-Nov-08
B C
Changed "Quad-ModeTM" to "Quad-Mode(R)" Change logo and fine print to ON Semiconductor
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
Doc. No. MD-5031 Rev. C
14
(c) 2008 SCILLC. All rights reserved. Characteristics subject to change without notice

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