RT8202AGQW Richtek USA Inc, RT8202AGQW Datasheet - Page 15

• Manufacturer Part Number: RT8202AGQW
• Description: IC PWM CTRLR SYNC BUCK 16WQFN
• Manufacturer: Richtek USA Inc

Specifications of RT8202AGQW

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Voltage - Supply: 4.5 V ~ 5.5 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 16-WFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Duty Cycle: -

For recommended operating conditions specification of
RT8202/A/B, where T
temperature of the die (125°C) and T
ambient temperature. The junction to ambient thermal
resistance θ
packages, the thermal resistance θ
standard JEDEC 51-7 four layers thermal test board. For
WQFN-14L 3.5x3.5 package, the thermal resistance θ
is 60°C/W on the standard JEDEC 51-7 four layers thermal
test board. The maximum power dissipation at T
can be calculated by following formula :
P
WQFN-16L 3x3 packages
P
WQFN-16L 4x4 packages
P
WQFN-14L 3.5x3.5 packages
The maximum power dissipation depends on operating
ambient temperature for fixed T
resistance θ
of derating curves allows the designer to see the effect of
rising ambient temperature on the maximum power
allowed.
DS8202/A/B-04 March 2011
D(MAX)
D(MAX)
D(MAX)
Figure 7. Derating Curves for RT8202/A/B Packages
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
= (125°C − 25°C) / (54°C/W) = 1.852W for
= (125°C − 25°C) / (60°C/W) = 1.667W for
= (125°C − 2°C) / (68°C/W) = 1.471W for
0
JA
JA
. For RT8202/A/B packages, the Figure 7
is layout dependent. For WQFN-16L 3x3
25
WQFN -16L 3x3
Ambient Temperature (°C)
J(MAX)
50
WQFN -16L 4x4
is the maximum junction
JA
J(MAX)
WQFN -14L 3.5x3.5
75
A
is 68°C/W on the
is the maximum
Four Layer PCB
and thermal
100
A
= 25°C
125
JA
Layout Considerations
Layout is very important in high frequency switching
converter design. If designed improperly, the PCB could
radiate excessive noise and contribute to the converter
instability. Certain points must be considered before
starting a layout for RT8202/A/B.
Connect RC low pass filter from VDDP to VDD, 1uF and
10Ω are recommended. Place the filter capacitor close
to the IC.
Keep current limit setting network as close as possible
to the IC. Routing of the network should avoid coupling
to high voltage switching node.
Connections from the drivers to the respective gate of
the high side or the low side MOSFET should be as
short as possible to reduce stray inductance.
All sensitive analog traces and components such as
VOUT, FB, GND, EN/DEM, PGOOD, OC, VDD, and
TON should be placed away from high voltage switching
nodes such as PHASE, LGATE, UGATE, or BOOT
nodes to avoid coupling. Use internal layer(s) as ground
plane(s) and shield the feedback trace from power traces
and components.
Current sense connections must always be made using
Kelvin connections to ensure an accurate signal, with
the current limit resistor located at the device.
Power sections should connect directly to ground
plane(s) using multiple vias as required for current
handling (including the chip power ground connections).
Power components should be placed to minimize loops
and reduce losses.
RT8202/A/B
www.richtek.com
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