CAT3606
6-Channel Low Noise Charge Pump
White LED Driver
FEATURES
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%
Output current up to 30mA per LED
High-frequency Operation at 1MHz
2 modes of operation 1x and 1.5x
White LED detect circuitry on all channels
Shutdown current less than 1µA
Small ceramic capacitors
Soft start and current limiting
Short circuit protection
16-pad TQFN package, 0.8mm max height
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 (R
SET
) 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 R
SET
pin current, or by
applying a PWM signal on the ENM and ENS pins.
¯¯¯
¯¯¯
The device is available in a 16-pad TQFN package
with a max height of 0.8mm.
For Ordering Information details, see page 11.
APPLICATION
Cell phone main and sub-display backlight
Navigation
PDAs
Digital Cameras
ORDERING INFORMATION
Part
Number
Package
Quantity
per Reel Marking
2000
2000
G366
CDBB
CAT3606HV4-T2 TQFN-16
(1)
CAT3606HV4-GT2 TQFN-16
(2)
Notes:
(1) Matte-Tin Plated Finish (RoHS-compliant).
(2) NiPdAu Plated Finish (RoHS-compliant).
TYPICAL APPLICATION CIRCUIT
1µF
1µF
Li-Ion
Battery
C1+
VIN
+
-
C
IN
1µF
ON/OFF
ENABLE
LED1-4
ENABLE
LED5-6
RSET
24kΩ
EN
ENM
ENS
RSET
C1- C2+
C2-
VOUT
Main Display
Sub Display
C
OUT
1µF
CAT3606
LED1
LED2
LED3
LED4
LED5
GND
LED6
20mA
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. MD-5009 Rev. C
CAT3606
PIN CONFIGURATION
(1)
TQFN 16-lead 4 x 4mm
(Top view)
LED5 LED4 LED3 LED2
16
LED6
EN
ENM
ENS
1
2
GND PAD
3
4
5
6
7
VIN
8
C1+
10 C2-
9 C1-
15
14
13
12 LED1
11 C2+
RSET VOUT
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+
C1
C2
C2+
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
Notes:
(1) The "exposed pad" under the package must be connected to the ground plane on the PCB.
Doc. No. MD-5009 Rev. C
2
©
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)
(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
ºC
ºC
ºC
V
V
RECOMMENDED OPERATING CONDITIONS
Parameter
VIN
Ambient Temperature Range
Input/Output/Bucket Capacitors
I
LED
per LED pin
I
OUT
Total Output Current
Range
3.0 to 5.5
-40 to +85
1
±
20% Typical
0 to 30
0 to 150
Unit
V
ºC
µF
mA
mA
ELECTRICAL OPERATING CHARACTERISTICS
Limits over recommended operating conditions unless specified otherwise. Typical values at T
A
= 25˚C,
V
IN
= 3.5V, I
RSET
= 5µA.
Symbol Parameter
I
Q
V
RSET
I
LED
I
LED
I
LED
I
LED-ACC
I
LED-DEV
R
OUT
f
OSC
T
DROPOUT
I
EN-CTR
V
EN-CTR
I
SC
I
LIM
Quiescent Current
RSET Regulated Voltage
I
RSET
= 5µA
I
RSET
= 37µA
Programmed LED Current
I
RSET
= 78µA
3.3
≤
VIN
≤
4.5V
LED Current Range with 6 LEDs
3.0
≤
VIN
≤
4.5V
LED Current Range with 4 LEDs 3.3
≤
VIN
≤
4.5V
0.5mA
≤
I
LED
≤
3mA
LED Current Accuracy
3mA
≤
I
LED
≤
30mA
LED Channel Matching
(I
LED
- I
LEDAVG
) / I
LEDAVG
Output Resistance (Open Loop) 1x Mode, 1.5x mode,
I
OUT
= 100mA
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
0.8
0.4
Conditions
V
EN
= 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
µA
mA
mA
V
mA
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
mA
mA
%
%
Ω
Ω
MHz
ms
µA
V
mA
mA
1.17
¯¯¯ ¯¯¯
On Inputs EN, ENM, ENS
¯¯¯ ¯¯¯
On Inputs EN, ENM, ENS
VOUT = GND
VOUT > 1V
Notes:
(1) Machine model is with 200pF capacitor discharged directly into each pin.
©
Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
3
Doc. No. MD-5009 Rev. C
CAT3606
BLOCK DIAGRAM
1µF
C1-
C1+ C2-
1µF
C2+
VIN
Battery
V
IN
3V to 4.2V
CIN
1µF
1x mode (LDO)
1.5x Charge Pump
VOUT
C
OUT
1MHz
Oscillator
Mode Control
LED1
LED2
LED3
LED4
LED5
1.2V Ref
Main
Sub
6 Current
Sink Regulators
LED6
20mA
1µF
EN
RSET
R
SET
24kΩ
ENM
ENS
Current
Setting
LED Output
Select
GND
Figure 2. 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.
Doc. No. MD-5009 Rev. C
4
©
Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3606
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.
Table 1. RSET Resistor Selection
LED Current (mA)
1
2
5
10
15
20
30
R
SET
(kΩ)
649
287
102
49.9
32.4
23.7
15.4
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
s
ink current is only about 0.2mA.
When the following equation is true on any channel,
the driver turns off the LED channel:
VOUT - V
LED
≤
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.
¯¯¯¯
The enable lines ENM and ¯¯¯¯ allow to turn On or
ENS
Off a group of LEDs as shown in Table 2.
Table 2: LED Selection
Control Lines
EN
0
1
1
1
1
¯¯¯¯
ENM
X
1
0
1
0
¯¯¯¯
ENS
X
1
1
0
0
LED Outputs
Main
LED1 - LED4
–
–
ON
–
ON
Sub
LED5 -LED6
–
–
–
ON
ON
Notes:
1 = logic high (or VIN)
0 = logic low (or GND)
– = LED output OFF
X = don't care
©
Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
5
Doc. No. MD-5009 Rev. C
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