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Número de pieza | CAT3643 | |
Descripción | 3-Channel Ultra High Efficiency Quad-Mode TM LED Driver | |
Fabricantes | Catalyst Semiconductor | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de CAT3643 (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
No Preview Available ! CAT3643
3-Channel Ultra High Efficiency Quad-Mode™
LED Driver
FEATURES
DESCRIPTION
High efficiency 1.33x charge pump
Quad-mode charge pump: 1x, 1.33x, 1.5x, 2x
Drives up to 3 LEDs at 32mA each
1-wire EZDim™ LED current programming
Power efficiency up to 92%
Low noise input ripple in all modes
The CAT3643 is a high efficiency quad-mode
fractional charge pump that can drive up to three
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
traditional 1.5x charge pumps with no added external
capacitors.
“Zero” current shutdown mode
Soft start and current limiting
Short circuit protection
Thermal shutdown protection
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 2.4V to 5.5V.
Tiny 12-lead XQFN, 12-lead TDFN and 16-lead
TQFN packages
The EN/DIM logic input functions as a chip enable and
a digital dimming interface for current setting of all
APPLICATION
LEDs. Six different current ratios are available via the
interface.
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The device is available in the tiny 12-lead XQFN 2.5 x
2.5mm with max height of 0.4mm or in 16-lead TQFN
or 12-lead TDFN 3mm x 3mm package with a max
Handheld Devices
height of 0.8mm.
ORDERING INFORMATION
Part
Package
Number
Package
Marking
CAT3643HV2-T2 TDFN-12 3 x 3mm(1) HABF
CAT3643HV3-T2 TQFN-16 3 x 3mm(1) JAAE
CAT3643HL1-T2 XQFN-12 2.5 x 2.5mm(1) LB
Notes:
(1) Matte-Tin Plated Finish (RoHS-compliant)
(2) Quantity per reel is 2000
For Ordering Information details, see page 16.
The 1.33x charge pump architecture with two fly
capacitors is patent pending.
TYPICAL APPLICATION CIRCUIT
1µF 1µF
VIN
2.4V
to
5.5V
CIN
1µF
1-Wire
EZDimTM
Programming
3.8kΩ
C1+
VIN
C1- C2+
C2-
VOUT
White LEDs
CAT3643
EN/DIM
RSET
GND
LED1
LED2
LED3
VOUT
COUT
1µF
20mA
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. 5022, Rev. B
1 page CAT3643
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, IOUT = 60mA (3 LEDs at 20mA), CIN = COUT = C1 = C2 = 1μF, TAMB = 25°C unless otherwise specified.
Efficiency vs. Input Voltage
100
VF = 3.3V
90
1x
80
1.33x
1.5x
2x
70
Efficiency vs. Li-Ion Voltage
100
VF = 3.3V
90 1x
80 1.33x
70
60 60
50 50
40
4.5
4.0 3.5 3.0 2.5
INPUT VOLTAGE [V]
2.0
40
4.2
4.0 3.8 3.6 3.4 3.2
INPUT VOLTAGE [V]
3.0
Quiescent Current vs. Input Voltage
4.0
VF = 3.3V
3.0
Quiescent Current vs. Temperature
4.0
2x 1.5x
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]
2.0
1.33x
1.0 1x
0.0
-40
0 40 80
TEMPERATURE [°C]
120
LED Current Change vs. Input Voltage
10
8 VF = 3.3V
6
4
2
0
-2
-4
-6
-8
-10
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
LED Current Change vs. Temperature
10
8 VF = 3.3V
6
4
2
0
-2
-4
-6
-8
-10
-40 0 40 80
TEMPERATURE [°C]
120
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
5
Doc. No. 5022, Rev. B
5 Page LED Current Selection
At power-up, the initial LED current is set to full scale
(100% brightness) by the external resistor RSET as
follows:
LED
current
=
132
×
0.6V
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
CAT3643
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
LED
Current
Shutdown
100%
TLO
100%
50%
25% 12.5% 6.25% 3.12%
Figure 3. EN/DIM Digital Dimming Timing Diagram
Table 1. LED Current Dimming Levels
EN/DIM
# of pulses *
EN = High
1st
2nd
3rd
4th
5th
6th
xth
RSET Gain
132
66
33
16.5
8.25
4.125
132
Device cycling through gain selection
* The gain is changed on the rising edges of the EN/DIM input.
LED Current
132 × 0.6V RSET
66 × 0.6V RSET
33 × 0.6V RSET
16.5 × 0.6V RSET
8.25 × 0.6V RSET
4.125 × 0.6V RSET
132 × 0.6V RSET
GAIN × 0.6V RSET
Shutdown
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
11
Doc. No. 5022, Rev. B
11 Page |
Páginas | Total 17 Páginas | |
PDF Descargar | [ Datasheet CAT3643.PDF ] |
Número de pieza | Descripción | Fabricantes |
CAT3643 | 3-Channel Ultra High Efficiency Quad-Mode TM LED Driver | Catalyst Semiconductor |
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