CATALYST CAT3648HV3-GT2

CAT3648
4-Channel Ultra High Efficiency Quad-Mode™
LED Driver with 32 Dimming Levels
DESCRIPTION
FEATURES
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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.
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 EZDim™ 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
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.
APPLICATION
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LCD Display Backlight
Cellular Phones
Digital Still Cameras
Handheld Devices
The device is available in the tiny 16-pad TQFN
3mm x 3mm package with a max height of 0.8mm.
Catalyst Semiconductor’s Quad-Mode™ 1.33x,
charge pump switching architecture is patented.
ORDERING INFORMATION
Part Number
CAT3648HV3-GT2
Qty per Reel
2000
(1)
Marking
JAAN
Notes: (1) NiPdAu Plated Finish (RoHS-compliant)
PIN CONFIGURATION
TYPICAL APPLICATION CIRCUIT
(Top View)
1µF
C1+
VIN
2.4V
to
5.5V
VOUT
COUT
1µF
3.74kΩ
1
C2VOUT
CIN
1-Wire
EZDimTM
Programming
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
C1- C2+
VIN
1µF
CAT3648
1µF
LED1
EN/DIM
LED2
RSET
LED3
GND
20mA
LED4
Doc. No. MD-5031, Rev. A
CAT3648
ABSOLUTE MAXIMUM RATINGS
Parameter
VIN, LEDx, C1±, C2±, EN/DIM voltage
VOUT voltage
Storage Temperature Range
Junction Temperature Range
Rating
6
7
-65 to +160
-40 to +150
Unit
V
V
°C
°C
Rating
2.5 to 5.5
-40 to +85
up to 30
1.3 to 4.3
Unit
V
°C
mA
V
RECOMMENDED OPERATING CONDITIONS
Parameter
VIN
Ambient Temperature Range
ILED per LED pin
LED Forward Voltage Range
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 = 25°C
Symbol
Name
IQ
Quiescent Current
IQSHDN
Shutdown Current
Conditions
LED Current Setting
ILED-ACC
LED Current Accuracy
(ILEDAVG – INOMINAL) / INOMINAL
RSET = 4.99kΩ
ILED-DEV
LED Channel Matching
(ILED - ILEDAVG) / ILEDAVG
RSET Regulated Voltage
ROUT
Output Resistance (open loop)
FOSC
Charge Pump Frequency
ISC_MAX
Output short circuit Current Limit
IIN_MAX
VHYS
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
TDF
Mode Transition Filter Delay
LEDTH
REN/DIM
VHI
VLO
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
Max
Units
mA
mA
mA
mA
1
µA
20
10
mA
±2
%
±1.5
%
0.58
0.6
0.8
1
0.8
5
5
10
1
1.3
VOUT > 1V, 1x mode
EN/DIM Pin
• Internal Pull-down Resistor
• Logic High Level
• Logic Low Level
Typ
1.0
1.7
2.2
2.4
1x mode, excluding load
1.33 x mode, excluding load
1.5x mode, excluding load
2x mode, excluding load
VEN = 0V
RSET = 3.74kΩ
RSET = 7.50kΩ
ILED-ACC
VRSET
Min
0.62
V
1.3
1.6
Ω
Ω
Ω
Ω
MHz
MHz
50
mA
250
mA
130
mV
400
mV
120
µs
100
kΩ
V
V
1.3
0.4
TSD
Thermal Shutdown
150
°C
THYS
Thermal Hysteresis
20
°C
VUVLO
Undervoltage lockout (UVLO) threshold
Doc. No. MD-5031, Rev. A
1.6
2
1.8
2.0
V
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3648
RECOMMENDED EN/DIM TIMING
For 2.4V ≤ VIN ≤ 5.5V, over full ambient temperature range -40ºC to +85ºC.
Symbol
Name
Conditions
Min
Typ
Max
Units
TLO
EN/DIM program low time
0.2
100
μs
THI
EN/DIM program high time
0.2
μs
TPWRDWN
EN/DIM low time to shutdown
1.5
ms
TLED
LED current settling time
40
μs
THI
EN/DIM
TLO
TPWRDWN
TLED
100%
LED
Current
100%
97% 94%
32 Levels
Shutdown
3%
Shutdown
0%
Figure 1. EN/DIM Digital Dimming Timing Diagram
Table 1. Resistor RSET and LED Current
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.
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
3
Full Scale
LED Current [mA]
RSET [kΩ]
2
37.4
5
14.7
10
7.50
15
4.99
20
3.74
25
3.00
30
2.49
Doc. No. MD-5031, Rev. A
CAT3648
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, IOUT = 80mA (4 LEDs at 20mA), CIN = COUT = C1 = C2 = 1μF, TAMB = 25°C unless otherwise specified.
Efficiency vs. Input Voltage
100
VF = 3.3V
100
1.33x
1.5x
90
1x
80
2x
70
60
40
4.2
2.0
4.0 3.8 3.6 3.4 3.2
INPUT VOLTAGE [V]
3.0
Quiescent Current vs. Temperature
4.0
4.0
VF = 3.3V
QUIESCENT CURRENT [mA]
QUIESCENT CURRENT [mA]
60
40
Quiescent Current vs. Input Voltage
3.0
2.0
1.0
LEDs Off
0.0
2x
2.0
1.0
1x
0.0
0
40
80
TEMPERATURE [°C]
120
LED Current Change vs. Temperature
LED CURRENT VARIATION [%] .
VF = 3.3V
10
8
6
4
2
VF = 3.3V
0
-2
-4
-6
-8
-10
-40
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
Doc. No. MD-5031, Rev. A
1.33x
-40
LED Current Change vs. Input Voltage
10
8
6
4
2
0
-2
-4
-6
-8
-10
1.5x
3.0
5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0
INPUT VOLTAGE [V]
LED CURRENT VARIATION [%] .
1.33x
70
50
4.0
3.5
3.0
2.5
INPUT VOLTAGE [V]
1x
80
50
4.5
VF = 3.3V
90
EFFICIENCY [%]
EFFICIENCY [%]
Efficiency vs. Li-Ion Voltage
4
0
40
80
TEMPERATURE [°C]
120
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3648
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, IOUT = 80mA (4 LEDs at 20mA), CIN = COUT = C1 = C2 = 1μF, TAMB = 25°C unless otherwise specified.
Output Resistance vs. Input Voltage
1.3
12
1.2
OUTPUT RESISTANCE [Ω] .
SWITCHING FREQUENCY [MHz]
Switching Frequency vs. Temperature
1.5x Mode
1.1
1.0
0.9
1.33x, 2x Mode
0.8
0.7
-40
0
40
80
TEMPERATURE [°C]
2x
10
8
6
4
2
1.33x
1.5x
1x
0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
120
Power Up in 1x Mode
Power Up in 1.33x Mode
Power Up in 1.5x Mode
Power Up in 2x Mode
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
5
Doc. No. MD-5031, Rev. A
CAT3648
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, IOUT = 80mA (4 LEDs at 20mA), CIN = COUT = C1 = C2 = 1μF, TAMB = 25°C unless otherwise specified.
Power Down Delay (1x Mode)
Power Up 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. A
6
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3648
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, IOUT = 80mA (4 LEDs at 20mA), CIN = COUT = C1 = C2 = 1μF, TAMB = 25°C unless otherwise specified.
LED Current vs. LED Pin Voltage
Foldback Current Limit
40
1x Mode
3.5
LED CURRENT [mA]
OUTPUT VOLTAGE [V]
4.0
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0
100
200
300
OUTPUT CURRENT [mA]
30
20
10
0
400
0
50 100 150 200 250
LED PIN VOLTAGE [mV]
300
Dimming Waveform
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
7
Doc. No. MD-5031, Rev. A
CAT3648
PIN DESCRIPTION
Pin #
Name
Function
1
LED2
LED2 cathode terminal.
2
LED3
LED3 cathode terminal.
3
LED4
LED4 cathode terminal.
4
RSET
Connect resistor RSET to set the LED current.
5
EN/DIM
6
VOUT
7
NC
Not connected inside the package.
8
VIN
Charge pump input, connect to battery or supply.
9
C1+
Bucket capacitor 1 Positive terminal
10
C1-
Bucket capacitor 1 Negative terminal
11
C2+
Bucket capacitor 2 Positive terminal
12
C2-
Bucket capacitor 2 Negative terminal
13
NC
Not connected inside the package.
14
NC
Not connected inside the package.
15
GND
Ground Reference
16
LED1
LED1 cathode terminal.
TAB
GND
Connect to GND on the PCB.
Device enable (active high) and Dimming Control.
Charge pump output connected to the LED anodes.
PIN FUNCTION
VIN is the supply pin for the charge pump. A small
1μF 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.
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.
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.
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.
VOUT is the charge pump output that is connected to
the LED anodes. A small 1μF 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.
Doc. No. MD-5031, Rev. A
8
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3648
BLOCK DIAGRAM
C1+
VIN
C1-
C2-
C2+
VOUT
1x mode (LDO)
4/3x, 3/2x, 2x Charge Pump
Mode Control
1, 1.3MHz
Oscillator
EN/DIM
LED1
100kΩ
LED2
Serial
Interface
Reference
Voltage
Registers
Current
Setting DAC
LED3
LED4
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.
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.
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 120μs). In 1.33x
mode, the output voltage is approximately equal to
1.33 times the input supply voltage (less any internal
voltage losses).
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
9
Doc. No. MD-5031, Rev. A
CAT3648
Table 2. Dimming Levels
LED Current Selection
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 ×
Full Scale
Current in %
Dimming
Pulses [n]
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
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
0.6V ⎛ 31 − n ⎞
×⎜
⎟
R SET ⎝ 31 ⎠
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
100µs. 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
TPWRDWN
TLED
100%
LED
Current
Shutdown
100%
97% 94%
32 Levels
3%
0%
Shutdown
Figure 3. EN/DIM Digital Dimming Timing Diagram
Doc. No. MD-5031, Rev. A
10
© Catalyst Semiconductor, Inc.
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).
The driver requires four external 1μF 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
1μF is sufficient.
1µF
C1+
VIN
CIN
C2VOUT
In 1x mode, the device operates in linear mode and
does not introduce switching noise back onto the
supply.
COUT
1µF
ENABLE
DIMMING
C1- C2+
VIN
1µF
CAT3648
LED1
EN/DIM
LED2
RSET
LED3
GND
RSET
1µF
Recommended Layout
LED4
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.
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.
GND
If the die temperature exceeds +150°C, the driver will
enter a thermal protection shutdown mode. When the
device temperature drops by about 20°C, the device
will resume normal operation.
Pin1
LED Selection
C2
EN/DIM
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.
C1
RSET
VIN
GND
COUT
CIN
GND
Figure 5. Recommended Layout
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.
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
11
Doc. No. MD-5031, Rev. A
CAT3648
PACKAGE OUTLINE DRAWING
TQFN 16-Pad 3 x 3mm (HS3, HV3)
(1)(2)
A
D
e
b
L
E
E2
PIN#1 ID
PIN#1 INDEX AREA
A1
TOP VIEW
SIDE VIEW
SYMBOL
MIN
NOM
MAX
A
0.70
0.75
0.80
A1
0.00
0.02
0.05
A3
A1
0.18
0.25
0.30
D
2.90
3.00
3.10
D2
1.40
–
1.80
E
2.90
3.00
3.10
E2
1.40
–
1.80
e
BOTTOM VIEW
A
0.20 REF
b
L
D2
A3
FRONT VIEW
0.50 BSC
0.30
0.40
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. A
12
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3648
EXAMPLE OF ORDERING INFORMATION
Prefix
CAT
Device #
3648
(1)(2)
Suffix
HV3
-G
Lead Finish
G: NiPdAu
Product Number
Optional
Company ID
T2
Package
HV3: TQFN
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 Catalyst Semiconductor Sales office.
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
13
Doc. No. MD-5031, Rev. A
REVISION HISTORY
Date
04/02/2008
Rev.
A
Reason
Initial Release
Copyrights, Trademarks and Patents
© Catalyst Semiconductor, Inc.
Trademarks and registered trademarks of Catalyst Semiconductor include each of the following:
Adaptive Analog™, Beyond Memory™, DPP™, EZDim™, LDD™, MiniPot™, Quad-Mode™ and Quantum Charge Programmable™
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-5031
Revision:
A
Issue date:
04/02/08