RT9301GJ8 Richtek USA Inc, RT9301GJ8 Datasheet - Page 7

• Manufacturer Part Number: RT9301GJ8
• Description: IC LED DVR 3CH RGB TSOT23-8
• Manufacturer: Richtek USA Inc

Specifications of RT9301GJ8

• Internal Driver: Yes
• Type - Primary: Backlight, Flash/Torch
• Type - Secondary: RGB, White LED
• Mounting Type: Surface Mount
• Number Of Outputs: 3
• Voltage - Supply: 2.8 V ~ 5.5 V
• Package / Case: SOT-23-8 Thin, TSOT-23-8
• Operating Temperature: -40°C ~ 85°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Topology: -
• Frequency: -
• Voltage - Output: -

GPIO Control
Figure 4 shows an application circuit for backlight with
GPIO. The three setting resistors are connected to GPIO.
The LED current can be controlled by GPIO directly. The
RT9301 provides low dropout voltage and 5% maximum
current matching. It also allows dimming control frequency
up to 10kHz.
The LED current can be set at different value with proper
setting resistor. For typical application of GPIO 1.8V/2.8V
and LED current 15mA/20mA, the recommended current
setting resistors are showed as below table.
DS9301-04 June 2009
GPIO
V
1.8
2.8
BAT
(V)
Figure 4. Application Circuit for Backlight with GPIO
GPIO
Figure 5. Application Circuit for Keypad Backlight
GPIO
(mA)
I
LED
15
20
15
20
V
1uF
BAT
Table 1. R
R
R
R
SET2
SET1
SET3
R
R
R
SET2
SET3
SET1
R
(kΩ)
101
48
36
76
SET
1uF
ISET1
ISET2
ISET3
SET
VIN
ISET1
ISET2
ISET3
Nearest Standard Values for
VIN
Value Selection
LED1
LED1
RT9301
GND
RT9301
R
GND
LED2
SET
47.5
100
36
75
LED2
(kΩ)
LED3
LED3
Figure 5 shows another application circuit for keypad
backlight with GPIO. There are 9 LEDs operation in parallel.
A battery or a regulated power source drives the LEDs.
Each channel supports three LEDs. The LED brightness
adjustment can be set with proper setting resistor for each
channel and be controlled from GPIO.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature 125 C. The
maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between
junction to ambient. The maximum power dissipation can
be calculated by following formula :
P
W here T
temperature 125 C, T
For recommended operating conditions specification of
RT9301, where T
temperature of the die (125 C) and T
ambient temperature. The junction to ambient thermal
resistance
108 C/W on the standard JEDEC 51-3 single-layer thermal
test board. The maximum power dissipation at T
can be calculated by following formula :
P
TSOT-23-8 packages
P
WDFN-8L 3x3 packages
The maximum power dissipation depends on operating
ambient temperature for fixed T
allows the designer to see the effect of rising ambient
temperature on the maximum power allowed.
JA
JA
JA
D(MAX)
D(MAX)
D(MAX)
. For RT9301 packages, the Figure 1 of derating curves
is the junction to ambient thermal resistance.
for TSOT-23-8 is 262 C/W, and WDFN-8L 3x3 is
)
= ( T
= (125 C
= (125 C
J(MAX)
JA
J(MAX)
is layout dependent. The thermal resistance
is the maximum operation junction
T
J(MAX)
25 C) / (262 C/W) = 0.382W for
A
A
25 C) / (108 C/W) = 0.926W for
is the ambient temperature and the
) /
JA
is the maximum junction
J(MAX)
and thermal resistance
A
RT9301
is the maximum
www.richtek.com
A
= 25 C
7