RT9167A-30GB Richtek USA Inc, RT9167A-30GB Datasheet - Page 10

• Manufacturer Part Number: RT9167A-30GB
• Description: IC REG LDO 3.0V 500MA SOT23-5
• Manufacturer: Richtek USA Inc

Specifications of RT9167A-30GB

• Regulator Topology: Positive Fixed
• Voltage - Output: 3V
• Voltage - Input: Up to 7V
• Voltage - Dropout (typical): 0.6V @ 500mA
• Number Of Regulators: 1
• Current - Output: 500mA (Min)
• Current - Limit (min): 500mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SC-74A, SOT-753
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

RT9167/A
Operating Region and Power Dissipation
The maximum power dissipation of RT9167/A depends
on the thermal resistance of the case and circuit board,
the temperature difference between the die junction and
ambient air, and the rate of airflow. The power dissipation
across the device is P = I
power dissipation is: PMAX = (T
where T
RT9167/A die junction and the surrounding environment,
θ
surrounding environment. The GND pin of the RT9167/A
performs the dual function of providing an electrical
connection to ground and channeling heat away. Connect
the GND pin to ground using a large pad or ground plane.
Current Limit and Thermal Protection
T9167
the pass transistor's gate voltage limiting the output current
to 350mA Typ. (700mA Typ. for RT9167A). Thermal-
overload protection limits total power dissipation in the
RT9167/A. When the
T
turning off the pass transistor and allowing the IC to cool.
The thermal sensor will turn the pass transistor on again
after the IC's junction temperature cools by 10°C, resulting
in a pulsed output during continuous thermal-overload
conditions. Thermal-overloaded protection is designed to
protect the RT9167/A in the event of fault conditions. Do
not exceed the absolute maximum junction-temperature
rating of T
can be shorted to ground for an indefinite amount of time
without damaging the part by cooperation of current limit
and thermal protection.
Thermal Considerations
Thermal protection limits power dissipation in RT9167/A.
When the operation junction temperature exceeds 165°C,
the OTP circuit starts the thermal shutdown function and
turns the pass element off. The pass element turn on again
after the junction temperature cools by 30°C.
For continuous operation, do not exceed absolute
maximum operation junction temperature 125°C. The
power dissipation definition in device is :
P
www.richtek.com
10
JA
J
D
= 155°C, the thermal sensor signals the shutdown logic
= (V
is the thermal resistance from the junction to the
includes a current limit which monitors and controls
IN
J
− T
− V
J
= 150°C for continuous operation. The output
A
OUT
is the temperature difference between the
) x I
OUT
junction temperature exceeds
+ V
OUT
IN
(V
x I
IN
J
Q
− V
− T
OUT
A
) /θ
). The maximum
JA
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
Where T
temperature 125°C, T
the θ
For recommended operating conditions specification of
RT9167/A, where T
temperature of the die (125°C) and T
ambient temperature. The junction to ambient thermal
resistance θ
the thermal resistance θ
JEDEC 51-3 single-layer thermal test board. The maximum
power dissipation at T
following formula :
P
SOT-23-5 package
P
SOP-8 package
The maximum power dissipation depends on operating
ambient temperature for fixed T
resistance θ
derating curves allows the designer to see the effect of
rising ambient temperature on the maximum power
allowed.
D(MAX)
D(MAX)
D(MAX)
Figure 5. Derating Curves for RT9167/A Packages
JA
700
600
500
400
300
200
100
0
is the junction to ambient thermal resistance.
= ( T
0
= (125°C - 25°C) / 160 = 0.625W for
= (125°C − 25°C) / 250 = 0.4W for
J(MAX)
SOP-8
SOT-23-5
JA
J(MAX)
JA
is layout dependent. For SOT-23-5 package,
. For RT9167/A packages, the Figure 5 of
20
is the maximum operation junction
− T
A
40
Ambient Temperature
J(MAX)
A
) / θ
A
is the ambient temperature and
JA
= 25°C can be calculated by
DS9167/A-28
JA
60
is 250°C/W on the standard
is the maximum junction
80
J(MAX)
A
100
September 2010
is the operated
and thermal
120
140