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CAT3643
Service Manual
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CATALYST CAT3643 Service Manual

3-Channel Ultra High Efficiency Quad-Mode™ LED Driver

CAT3643

FEATURES

High efficiency 1.33x charge pump
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
“Zero” current shutdown mode
Soft start and current limiting
Short circuit protection
Thermal shutdown protection
Tiny 12-pad XQFN, 12-pad TDFN and 16-pad
TQFN packages

APPLICATION

LCD Display Backlight
Cellular Phones
Digital Still Cameras
Handheld Devices

DESCRIPTION

The CAT3643 is a high efficiency Quad-ModeTM 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.
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.
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 12-pad XQFN 2.5 x
2.5mm with max height of 0.4mm or in 16-pad TQFN or 12-pad TDFN 3mm x 3mm package with a max height of 0.8mm.

ORDERING INFORMATION

Part Number Package Marking
CAT3643HV2-T2 TDFN-12 3 x 3
CAT3643HV2-GT2 TDFN-12 3 x 3
CAT3643HV3-T2 TQFN-16 3 x 3
CAT3643HV3-GT2 TQFN-16 3 x 3
CAT3643HL1-T2 XQFN-12 2.5 x 2.5
Notes:
(1) Matte-Tin Plated Finish (RoHS-compliant)
(2) NiPdAu Plated Finish (RoHS-compliant)
(3) Quantity per reel is 2000
(1)
HABF
(2)
HABG
(1)
JAAE
(2)
JAAF
(1)
For Ordering Information details, see page 16.
LB
TM
Catalyst Semiconductor’s Quad-Mode
1.33x charge
pump switching architecture is patented.

TYPICAL APPLICATION CIRCUIT

V
IN
C
2.4V to
1µF
5.5V
1-Wire
EZDim
Programming
4.02k
IN
TM
V
IN
EN/DIM
RSET
1µF
C1-C1+ C2-C2+
CAT3643
GND
1µF
V
OUT
LED1
LED2
LED3
V
OUT
20mA
C
1µF
OUT
© Catalyst Semiconductor, Inc. 1 Doc. No. MD-5022 Rev. E Characteristics subject to change without notice
CAT3643

PIN CONFIGURATION

TDFN 12-Pad 3 x 3mm
(Top View)
1
LED1
211LED2 C2+
3
LED3
4
RSET
58EN/DIM C1+
6
VOUT
12
10
GND
C2-
9
C1-
7
VIN
TQFN 16-Pad 3 x 3mm
(Top View)
LED1
GND
NC
1
LED2
2
LED3
3
NC
4
RSET
EN/DIM
VOUT
NC
13141516
NC
8765
VIN
12
11
10
C2-
C2+
C1-
9
C1+
XQFN 12-Pad 2.5 x 2.5mm
(Top View)
C2-
GND
C2+
1
2
C1+
C1-
101112
9
VIN
VOUT
8
3
LED1
LED2
The CAT3643 is offered in three different packages. The 12-pad TDFN 3mm x 3mm with a max height of
0.8mm is pin-compatible to the Catalyst CAT3603 LED driver. The 12-pad XQFN provides the smallest
7
EN/DIM
654
LED3
RSET
footprint with a package size of 2.5mm x 2.5mm and
0.4mm max height. The 16-pad TQFN 3mm x 3mm with max height of 0.8mm is also offered.
Doc. No. MD-5022 Rev. E 2 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3643

ABSOLUTE MAXIMUM RATINGS

Parameter Rating Unit
VIN, LEDx, C1±, C2±, EN/DIM, RSET voltage 6 V V
voltage 7 V
OUT
Storage Temperature Range -65 to +160 Junction Temperature Range -40 to +150

RECOMMENDED OPERATING CONDITIONS

Parameter Rating Unit
VIN 2.5 to 5.5 V Ambient Temperature Range -40 to +85 I
per LED pin up to 30 mA
LED
LED Forward Voltage Range 1.3 to 4.3 V
Typical application circuit with external components is shown on page 1.

ELECTRICAL OPERATING CHARACTERISTICS

(over recommended operating conditions unless specified otherwise) V
Symbol Name Conditions Min Typ Max Units
1x mode, no load
IQ Quiescent Current
1.33 x mode, no load
1.5x mode, no load 2x mode, no load
I
Shutdown Current VEN = 0V 1 µA
QSHDN
(I
– I
I
I
LED Current Accuracy
LED-ACC
LED Channel Matching (I
LED-DEV
V
RSET Regulated Voltage
RSET
LEDAVG
RSET = 5k
LED
- I
NOMINAL
LEDAVG
) / I
1x mode
R
Output Resistance (open loop)
OUT
1.33x mode, V
1.5x mode, V 2x mode, V
F
OSC
I
SC_MAX
I
IN_MAX
LEDTH
V
HYS
T
DF
R
EN/DIM
VHI V
LO
Charge Pump Frequency
Output short circuit Current Limit V
Input Current Limit V
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 400 mV
Transition Filter Delay 500 µs
EN/DIM Pin
• Internal Pull-down Resistor
• Logic High Level
• Logic Low Level
1.33x and 2x mode
1.5x mode < 0.5V 50 mA
OUT
> 1V 250 mA
OUT
130 mV
IN
= 2.7V
IN
= 2.4V
IN
TSD Thermal Shutdown 150
T
Thermal Hysteresis 20
HYS
V
Undervoltage lockout (UVLO) threshold 1.6 1.8 2.0 V
UVLO
°C °C
°C
= 3.6V, EN = High, T
IN
= 25°C
AMB
1.0
1.7
2.2
2.4
) / I
NOMINAL
±1.5 %
LEDAVG
±2 %
0.58 0.6 0.62 V
0.8
= 3V
5 5
10
0.8 1
1.3
1
1.3
100
1.3
1.6
0.4
mA mA mA mA
   
MHz MHz
k
V V
°C °C
© Catalyst Semiconductor, Inc. 3 Doc. No. MD-5022 Rev. E Characteristics subject to change without notice
CAT3643

RECOMMENDED EN/DIM TIMING

For 2.4V ≤ V
Symbol Name Conditions Min Typ Max Units
T
SETUP
TLO EN/DIM program low time 0.2 100 s
THI EN/DIM program high time 0.2 s
T
PWRDWN
T
LED current settling time 40 s
LED
≤ 5.5V, over full ambient temperature range -40ºC to +85ºC.
IN
EN/DIM setup from shutdown 10 s
EN/DIM low time to shutdown 1.5 ms
T
PWRDWN
EN/DIM
T
SETUP
T
LED
T
HI
T
LO
100%
50%
LED Current
Shutdown
25%
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.
12.5%
100%
6.25%
3.12%
Shutdown
LED Current (mA) RSET (kΩ)
2 40.0
5 15.8
10 7.87
15 5.23
20 4.02
25 3.16
30 2.67
Table 1. Resistor RSET and LED Current
Doc. No. MD-5022 Rev. E 4 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice

TYPICAL PERFORMANCE CHARACTERISTICS

.
.
V
= 3.6V, I
IN
= 60mA (3 LEDs at 20mA), CIN = C
OUT
Efficiency vs. Input Voltage
= C1 = C2 = 1F, T
OUT
= 25°C unless otherwise specified.
AMB
Efficiency vs. Li-Ion Voltage
CAT3643
100
VF = 3.3V
90
1.33x
1.5x
1x
80
2x
70
60
EFFICIENCY [%]
50
40
INPUT VOLTAGE [V]
Quiescent Current vs. Input Voltage
4.0 VF = 3.3V
3.0
2.0
100
VF = 3.3V
90
80
70
60
EFFICIENCY [%]
50
40
2.02.53.03.54.04.5
1x
1.33x
3.03.23.43.63.84.04.2
INPUT VOLTAGE [V]
Quiescent Current vs. Temperature
4.0
2x 1.5x
3.0
2.0
1.33x
1.0
QUIESCENT CURRENT [ mA]
0.0
LEDs Off
2.02.53.03.54.04.55.05.5
INPUT VOLTAGE [V]
1.0
QUIESCENT CURRENT [mA]
0.0
-40 0 40 80 120 TEMPERATURE [°C]
1x
LED Current Change vs. Input Voltage
10
VF = 3.3V
8
6
4
2
0
-2
-4
-6
-8
-10
LED CURRENT VARI ATION [ %]
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
VF = 3.3V
8
6
4
2
0
-2
-4
-6
-8
-10
LED CURRENT VARIATION [%]
-40 0 40 80 120 TEMPERA TURE [°C]
© Catalyst Semiconductor, Inc. 5 Doc. No. MD-5022 Rev. E Characteristics subject to change without notice
CAT3643
.
TYPICAL PERFORMANCE CHARACTERISTICS
V
= 3.6V, I
IN
= 60mA (3 LEDs at 20mA), CIN = C
OUT
Switching Frequency vs. Temperature
= C1 = C2 = 1F, T
OUT
= 25°C unless otherwise specified.
AMB
Output Resistance vs. Input Voltage
1.3
1.2
1.5x Mode
1.1
1.0
0.9
1.33x, 2x Mode
0.8
0.7
SWITCHING FREQUENCY [MHz]
-40 0 40 80 120 TEMPERATURE [°C]
Power Up in 1x Mode
12
10
8
6
1.5x
4
2
OUTPUT RESISTANCE []
0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
2x
1.33x
1x
INPUT VOLTAGE [V]
Power Up in 1.33x Mode
Power Up in 1.5x Mode
Power Up in 2x Mode
Doc. No. MD-5022 Rev. E 6 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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