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CAT3606
6-Channel Low Noise Charge Pump White LED Driver FEATURES
I I I I I
Drives up to 4 main LEDs and 2 sub LEDs Separate control for main and sub LEDs Compatible with supply voltage of 3V to 5.5V Power efficiency up to 90%
I I
White LED detect circuitry on all channels I Shutdown current less than 1A Small ceramic capacitors I Soft start and current limiting I Short circuit protection I 16-lead thin QFN package, 0.8mm max height
Output current up to 30mA per LED I High-frequency Operation at 1MHz I 2 modes of operation 1x and 1.5x
APPLICATIONS
I I
Cell phone main and sub-display backlight Navigation
I
PDAs I Digital Cameras
DESCRIPTION
The CAT3606 controls up to four LEDs for the main display and two LEDs for the sub-display in cellular phones. The device is capable of operating in either 1x (LDO) mode or 1.5x charge pump mode. All LED pin currents are regulated and tightly matched to achieve uniformity of brightness across the LCD backlight. An external resistor (RSET) sets the nominal output current. The device can deliver as much as 20mA per channel during low voltage operation (3V), and 30mA per channel during nominal operation (3.3V). A constant high-frequency switching scheme (1MHz) provides low noise and allows the use of very small value ceramic capacitors. A "zero" quiescent current mode can be achieved via the chip enable pin EN. The Main and Sub LEDs each have their own dedicated ON/OFF control pins (ENM, ENS). Dimming can be achieved using either a DC voltage to control the RSET pin current, or by applying a PWM signal on the ENM and ENS pins. The device is available in a 16-lead thin QFN package with a max height of 0.8mm.
TYPICAL APPLICATION CIRCUIT
C1+ VIN Li-Ion Battery + CIN
C1- C2+
C2VOUT
Main Display
Sub Display COUT
CAT3606
ON/OFF ENABLE LED1-4 ENABLE LED5-6 EN ENM ENS RSET RSET GND LED6 LED1 LED2 LED3 LED4 LED5 20mA
(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
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Doc. No. 5009, Rev. B
CAT3606
ORDERING INFORMATION
Part Number CAT3606HS4 CAT3606HV4 Package Thin QFN-16 4x4mm Thin QFN-16 4x4mm Lead Free Quantity per Reel 2000 2000 Package Marking C366 G366
PIN CONFIGURATION
Top View
LED5 LED4 LED3 LED2 16 LED6 1 15 14 13 12 LED1 11 C2+ GND PAD ENM 3 10 C29 C15 6 7 VIN 8 C1+
EN
2
ENS
4
RSET VOUT
16-lead Thin QFN (4mm x 4mm)
Note: The "exposed pad" under the package must be connected to the ground plane on the PCB.
PIN DESCRIPTIONS
Pin Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 PAD Name LED6 EN ENM ENS RSET VOUT VIN C1+ C1C2C2+ LED1 LED2 LED3 LED4 LED5 GND Function LED6 cathode terminal Enable/shutdown input, active high Enable "main" input for LED1 to LED4, active low Enable "sub" input for LED5 and LED6, active low The LED output current is set by the current sourced out of the RSET pin Charge pump output connected to the LED anodes Supply voltage Bucket capacitor 1 terminal Bucket capacitor 1 terminal Bucket capacitor 2 terminal Bucket capacitor 2 terminal LED 1 cathode terminal LED 2 cathode terminal LED 3 cathode terminal LED 4 cathode terminal LED 5 cathode terminal Ground reference
Doc. No. 5009, Rev. B
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(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3606
ABSOLUTE MAXIMUM RATINGS
Parameter VIN, VOUT, LEDx voltage EN, ENM, ENS voltage RSET voltage RSET current Ambient Temperature Range Storage Temperature Range Lead Temperature ESD Ratings Human Body Model (HBM) Machine Model (MM) (note 1)
Note 1:
Rating -0.3 to 7.0 -0.3 to VIN -0.3 to VIN +1 -40 to +85 -65 to +160 300 2000 200
Unit V V V mA o C o C o C V V
Machine model is with 200pF capacitor discharged directly into each pin.
RECOMMENDED OPERATING CONDITIONS
Parameter VIN Ambient Temperature Range Input/Output/Bucket Capacitors ILED per LED pin IOUT Total Output Current Rating 3.0 to 5.5 -40 to +85 1 +20% typical 0 to 30 0 to 150 Unit V o C F mA mA
ELECTRICAL OPERATING CHARACTERISTICS
Limits over recommended operating conditions unless specified otherwise. Typical values at TA = 25C, VIN = 3.5V, IRSET = 5A.
Symbol IQ VRSET ILED ILED ILED ILED-ACC ILED-DEV ROUT fOSC TDROPOUT IEN-CTR VEN-CTR ISC ILIM
Parameter Quiescent Current RSET Regulated Voltage Programmed LED Current LED Current Range with 6 LEDs LED Current Range with 4 LEDs LED Current Accuracy LED Channel Matching Output Resistance (Open Loop) Charge Pump Frequency 1x to 1.5x Mode Transition Dropout Delay Input Leakage Current High Detect Threshold Low Detect Threshold Input Current Limit Maximum Input Current
Conditions VEN = 0V 1x Mode, No Load 1.5x Mode, No Load
Min
Typ 0.1 0.3 2.6 1.2 2.4 15.0 30.0
Max 1 1 5 1.23
Unit A mA mA V mA mA mA mA mA mA % % % MHz ms A V V mA mA
1.17 IRSET = 5A IRSET = 37A IRSET = 78A 3.3 VIN 4.5 V 3.0 VIN 4.5 V 3.0 VIN 4.5V 0.5mA ILED 3mA 3mA ILED 30mA (ILED - ILEDAVG) / ILEDAVG 1x Mode 1.5x Mode, IOUT = 100mA 0.8 0.4 On Inputs EN, ENM, ENS On Inputs EN, ENM, ENS VOUT = GND VOUT > 1V
3
30 20 30 +15 +5 +3 1.4 6.5 1.0 0.6 2.5 10 1.3 0.9 1 0.4 30 200 0.8 0.7 45 400 1.3 60 600
(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
Doc. No. 5009, Rev. B
CAT3606
BLOCK DIAGRAM
C1C1+ C2C2+
3VIN4.2V Battery
+ -
VIN CIN
1x mode (LDO) 1.5x Charge Pump
VOUT COUT
1MHz Oscillator EN
Mode Control LED1 LED2 LED3 LED4 20mA
1.2V Reference RSET Current Setting Main Sub
LED5 LED6
6 Current Sink Regulators ENM ENS LED Output Selection
GND
Figure 1: CAT3606 Functional Block Diagram
BASIC OPERATION
At power-up, the CAT3606 starts operation in 1x mode. If it is able to drive the programmed LED current, it continues in 1x mode. If the battery voltage drops to a level where the LED current cannot be met, the driver automatically switches into 1.5x mode, to boost the output voltage high enough to achieve the nominal LED current. The above sequence is reinitialized each and every time the chip is powered up or is taken out of shutdown mode (via EN pin). The use of the Main and Sub display enable pins (ENM or ENS) does not affect the mode of operation.
LED CURRENT SETTING
The LED current is set by the external resistor RSET connected between the RSET pin and ground. Table 1 lists various LED currents and the associated RSET resistor value for standard 1% precision surface mount resistors.
LED Current (mA) 1 2 5 10 15 20 30 RSET (k) 649 287 102 49.9 32.4 23.7 15.4
Table 1. RSET Resistor Selection
Doc. No. 5009, Rev. B
4
(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3606 The enable lines ENM and ENS allow to turn On or Off a group of LEDs as shown in Table 2.
Control Lines EN 0 1 1 1 1 ENM X 1 0 1 0 ENS X 1 1 0 0 LED Outputs Sub Main
LED1 - LED4 LED5 - LED6
The unused LED channels can also be turned off by connecting the respective LED pins to VOUT. In which case, the corresponding LED driver is disabled and the typical LED sink current is only about 0.2mA. When the following equation is true on any channel, the driver turns off the LED channel: VOUT - VLED 1V (LED channel OFF) Note: The CAT3606 is designed to drive LEDs with forward voltage greater than 1V and is not compatible with resistive loads.
ON ON
ON ON
Table 2: LED Selection Notes: 1 = logic high (or VIN) 0 = logic low (or GND) - = LED output OFF X = don't care
(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
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Doc. No. 5009, Rev. B
CAT3606
TYPICAL CHARACTERISTICS
VIN = 3.6V, EN = VIN, ENM = ENS = GND, CIN = COUT = 1F, RSET = 24k (20mA per LED), TAMB = 25C, unless otherwise specified. Efficiency vs. Input Voltage (6 LEDs)
100
Efficiency vs. Total LED Current (6 LEDs)
100
1x mode 1.5x mode
EFFICIENCY [%]
90 80 70 60 50 40
EFFICIENCY [%]
90 80 70 60 50 40
VIN = 4V (1x mode)
20mA per LED
VIN = 3.2V (1.5x mode)
15mA per LED
4.2
4.0
3.8
3.6
3.4
3.2
3.0
0
50
100
150
200
INPUT VOLTAGE [V]
TOTAL LED CURRENT [mA]
LED Current Change vs. Input Voltage
LED Current Change vs. Temperature
LED CURRENT CHANGE [%]
LED CURRENT CHANGE [%]
1.5 1.0 6 LEDs at 15mA 0.5 0.0 -0.5 -1.0 -1.5 3.0 3.2 3.4 3.6 3.8 4.0 4.2
4 3 2 1 0 -1 -2 -3 -4 -50 -25 0 25 50 75 100 125 6 LEDs at 15mA Vin = 4V
INPUT VOLTAGE [V]
TEMPERATURE [C]
Ground Current vs. Input Voltage (1x mode)
0.5
Ground Current vs. Temperature (1x mode)
0.5
GROUND CURRENT [mA]
0.4 0.3 0.2
GROUND CURRENT [mA]
0.4 0.3 0.2 0.1 0.0 -40 -20 0 20 40 60 80 100
6 LEDs OFF
0.1 0.0 3.0 3.2 3.4 3.6 3.8 4.0 4.2
6 LEDs OFF Rset = 500k
INPUT VOLTAGE [V]
TEMPERATURE [C]
Doc. No. 5009, Rev. B
6
(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3606
TYPICAL CHARACTERISTICS
VIN = 3.6V, EN = VIN, ENM = ENS = GND, CIN = COUT = 1F, RSET = 24k (20mA per LED), TAMB = 25C, unless otherwise specified. Ground Current vs. Input Voltage (1.5x mode) Supply Current vs. Input Voltage
GROUND CURRENT [mA]
5.0
SUPPLY CURRENT [mA]
140
4.0 3.0 2.0 1.0 0.0 3.0 3.2 3.4 3.6 3.8 4.0 4.2
1.5x mode
120
100
VIN = 3.6V all LEDs open
1x mode 6 LEDs at 15mA
80 3.0
3.2
3.4
3.6
3.8
4.0
4.2
INPUT VOLTAGE [V]
INPUT VOLTAGE [V]
Oscillator Frequency vs. Input Voltage
1.10
Oscillator Frequency vs. Temperature
1.10
CLOCK FREQUENCY [MHz]
CLOCK FREQUENCY [MHz]
1.05
1.05
1.00
1.00
6 LEDs at 20mA
0.95
0.95 VIN = 3.6V 6 LEDs at 15mA -40 -20 0 20 40 60 80 TEMPERATURE [C] 100
0.90 3.0 3.2 3.4 3.6 3.8 4.0 4.2
0.90
INPUT VOLTAGE [V]
Output Resistance vs. Input Voltage (1x mode)
4
Output Resistance vs. Input Voltage (1.5x mode)
10
OUTPUT RESISTANCE []
OUTPUT RESISTANCE []
3 100mA load 100mA load 2
8
6
100mA load 100mA load
1
4
0 3.0
3.2
3.4
3.6
3.8
4.0
4.2
2 3.0
3.2
3.4
3.6
3.8
4.0
4.2
INPUT VOLTAGE [V]
INPUT VOLTAGE [V]
(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
7
Doc. No. 5009, Rev. B
CAT3606
TYPICAL CHARACTERISTICS
VIN = 3.6V, EN = VIN, ENM = ENS = GND, CIN = COUT = 1F, RSET = 24k (20mA per LED), TAMB = 25C, unless otherwise specified. Switching Waveforms in 1.5x Mode Operating Waveforms in 1x Mode
Power Up 6 LEDs at 15mA, VIN = 3V (1.5x Mode)
Power Up 6 LEDs at 15mA, VIN = 3.6V (1x Mode)
LED Current vs. RSET
100.0
Line Transient Response in 1x Mode
LED CURRENT [mA]
10.0
1.0
0.1 10 100 1000 10000
RSET [kohm]
Doc. No. 5009, Rev. B
8
(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3606
TYPICAL CHARACTERISTICS
VIN = 3.6V, EN = VIN, ENM = ENS = GND, CIN = COUT = 1F, TAMB = 25C, unless otherwise specified. Foldback Current Limiting RSET Pin Voltage vs. Temperature
1.24
5
OUTPUT VOLTAGE [v]
4 3 2 1 0 0
1x mode
RSET PIN VOLTAGE [v]
1.22 1.20
1.18 1.16
100 200 300 400 OUTPUT CURRENT [mA]
500
-50
-25
0
25
50
75
100
125
TEMPERATURE [C]
PWM Dimming at 1kHz on ENM and ENS
RECOMMENDED LAYOUT
When the driver is in the 1.5x charge pump mode, the 1MHz switching frequency operation requires to minimize trace length and impedance to ground on all 4 capacitors. A ground plane should cover the area on the bottom side of the PCB opposite to the IC and the bypass capacitors. Capacitors Cin and Cout require short connection to ground which can be done with multiple vias as shown on Figure 2. A square copper area matches the QFN16 exposed pad (GND) and must be connected to the ground plane underneath. The use of multiple via will improve the heat dissipation.
Figure 2: PCB Layout
(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
9
Doc. No. 5009, Rev. B
CAT3606
PACKAGE DRAWING AND DIMENSIONS THIN QFN 16-LEAD 4MM X 4MM
Recommended Land Pattern
0.65 mm
4.00+0.10 (S)
1.95 mm
2.25 mm 0.35 mm
0.75+0.05
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS. COPLANARITY SHALL NOT EXCEED 0.08mm. 3. WARPAGE SHALL NOT EXCEED 0.10mm.
PIN 1 INDEX AREA
4.00+0.10 (S)
0.20 REF.
DAP SIZE 2.5 X 2.5
2.10+0.10
2.10+0.10
0.76 mm
2.25 mm
C0.35
NOTE: 1. ALL DIMENSIONS ARE IN mm. ANGLES IN DEGREES.
0.55+0.10
0.0-0.05 0.30+0.05 0.65 TYP 1.95 REF. (2x)
4. PACKAGE LENGTH/PACKAGE WIDTH ARE CONSIDERED AS SPECIAL CHARACTERISTIC. (S)
Doc. No. 5009, Rev. B
10
(c) 2005 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
4.41 mm
REVISION HISTORY
Date 1/21/2005 08/01/2005 Rev. A B Reason Initial issue Update LED Current Setting
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Publication #: Revison: Issue date:
5009 B 08/01/05

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