RT9300A/B
Tiny Package, Low Dropout Current Source
General Description
The RT9300A/B low-dropout bias supply for white LEDs
is a high-performance alternative to the simple ballast
resistors used in conventional white LED designs. The
RT9300A/B uses an internal resistor to set the bias
current for four LEDs, which are matched to 5%. The
RT9300A/B's advantages over ballast resistors include
much lower bias variation with supply voltage variation,
significantly lower dropout voltage, and in some applications,
significantly improved efficiency. The RT9300A/B requires
only a 60/45mV dropout voltage at a 20/15mA load on
each output to match the LED brightness.
Features
Low 60/45mV Dropout at 20/15mA
5% LED Current Matching
Simple LED Brightness Control
2.5V to 5.5V Supply Voltage Range
Thermal Shutdown Protection
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Next-Generation Wireless Handsets
PDAs, Palmtops, and Handy Terminals
Digital Cameras, Camcorders
Battery-Powered Equipment
Ordering Information
RT9300A/B
Package Type
E : SOT-23-6
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Sink Current
A : 20mA
B : 15mA
Note :
Richtek products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Pin Configurations
(TOP VIEW)
LED1 LED2 LED3
6
5
4
2
3
EN GND LED4
SOT-23-6
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
Typical Application Circuit
V
IN
C
0.1uF
6
LED1
Enable
1
EN
5
LED2
4
LED3
3
LED4
RT9300A/B
GND
2
Figure 1. Application Circuit for Backlight.
DS9300A/B-05 April 2011
www.richtek.com
1
RT9300A/B
V
IN
Keypad
LED
C
0.1uF
6
LED1
PWM
1
EN
5
LED2
4
LED3
3
LED4
RT9300A/B
GND
2
Figure 2. Application Circuit for Keypad.
Function Block Diagram
EN
LED2
LED4
LED1
LED3
Bandgap
V
REF
+
-
UVLO
Current Source
OTP
I
REF
Functional Pin Description
Pin
1
2
3
Name
EN
GND
LED4
Chip Enable (Active High).
Ground
LED4 Cathode Connection. Current flowing into LED4 is Constant. (20mA/15 mA)
LED4 is High Impedance when EN is Low.
4
LED3
LED3 Cathode Connection. Current flowing into LED3 is Constant. (20mA/15 mA)
LED3 is High Impedance when EN is Low.
5
LED2
LED2 Cathode Connection. Current flowing into LED2 is Constant. (20mA/15 mA)
LED2 is High Impedance when EN is Low.
6
LED1
LED1 Cathode Connection. Current flowing into LED1 is Constant. (20mA/15 mA)
LED1 is High Impedance when EN is Low.
Function
www.richtek.com
2
DS9300A/B-05 April 2011
RT9300A/B
Absolute Maximum Ratings
(Note 1)
Supply Input Voltage, V
IN
------------------------------------------------------------------------------------------------
The other pins --------------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
SOT-23-6 --------------------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
SOT-23-6,
θ
JA
---------------------------------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------
−
0.3V to 6V
−
0.3V to 6V
0.4W
250°C/W
260°C
Operation Temperature Range -----------------------------------------------------------------------------------------
−
40°C to 85°C
Junction Temperature ----------------------------------------------------------------------------------------------------- 150°C
Storage Temperature Range --------------------------------------------------------------------------------------------
−
65°C to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ---------------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ------------------------------------------------------------------------------------------------------ 200V
Recommended Operating Conditions
(Note 4)
Junction Temperature Range --------------------------------------------------------------------------------------------
−
40°C to 125°C
Ambient Temperature Range --------------------------------------------------------------------------------------------
−
40°C to 85°C
Electrical Characteristics
(V
IN
= 3.7V, T
A
= 25°C, Unless Otherwise specification)
Parameter
System Supply Input
Operation Voltage Range
Under Voltage Lock Out
UVLO Hysteresis
Symbol
Test Conditions
Min
Typ
Max
Unit
V
EN
V(UVLO)
Falling
2.5
--
--
RT9300A
18
13.5
--
--
--
--
--
2.1
100
20
15
--
60
45
--
--
--
170
10
--
5.5
--
--
22
V
V
mV
mA
LED Sink Current
RT9300B
Quiescent Current
LED Dropout Voltage
LED Current Deviation Matching
EN High-Level Input Voltage
EN Low-Level Input Voltage
OTP
OTP Hysteresis
Shutdown Current
I
SHDN
V
EN
< 0.4V
V
EN_H
V
EN_L
I
EN
I
LED
= 0
I
LED
= 20mA
I
LED
= 15mA
16.5
600
--
uA
mV
--
5
--
0.7
--
--
1
%
V
V
°C
°C
uA
2.5
--
--
--
--
DS9300A/B-05 April 2011
www.richtek.com
3
RT9300A/B
Note 1.
Stresses listed as the above
“Absolute
Maximum Ratings” may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
Note 2.
θ
JA
is measured in the natural convection at T
A
= 25°C on a low effective single layer thermal conductivity test board of
JEDEC 51-3 thermal measurement standard.
Note 3.
Devices are ESD sensitive. Handling precaution is recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions.
Note 5.
Floating connection or pull low to disable this function.
www.richtek.com
4
DS9300A/B-05 April 2011
RT9300A/B
Typical Operating Characteristics
LED Current vs. Input Voltage
18
16
14
18
16
LED Current vs.
LED Current vs.
EN Voltage
Voltage
V
IN
= 3.7V
14
LED Current (mA)
12
10
8
6
4
2
0
2
2.5
3
LED Current (mA)
LED Current (mA)
4
4.5
5
LED 1
LED 2
LED 3
LED 4
12
10
8
6
4
2
0
3.5
1.5
1.75
2
2.25
2.5
2.75
3
3.25
3.5
Input Voltage (V)
EN Voltage
(V)
EN Voltage
(V)
LED Current vs. Temperature
15.5
400
350
EN Current vs. EN
Supply Voltage
EN Current vs. EN
Supply Voltage
V
IN
= 3.5V
15.4
300
LED Current (mA)
EN Current (uA)
EN Current (uA)
-40 -30 -20 -10 0
10 20 30 40 50 60 70 80 90
15.3
250
200
150
100
50
15.2
15.1
15
0
1.5
2
2.5
3
3.5
4
4.5
Temperature
(°C)
EN Supply Voltage
(V)
EN Supply Voltage
(V)
EN Pin Dimming Operation
EN Pin Shutdown Response
V
EN
= 0V to 3V
(2V/Div)
EN Pin
Voltage
EN Pin
Voltage
(2V/Div)
LED
Current
(10mA/Div)
LED
Current
(10mA/Div)
Time (50us/Div)
Time (50us/Div)
DS9300A/B-05 April 2011
www.richtek.com
5
全文预览
51单片机
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
