RT8010-12GQW Richtek USA Inc, RT8010-12GQW Datasheet - Page 12

• Manufacturer Part Number: RT8010-12GQW
• Description: IC DCDC CONV STP-DN SYNC 6WDFN
• Manufacturer: Richtek USA Inc
• Type: Step-Down (Buck), PWMr

Specifications of RT8010-12GQW

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 1.2V
• Current - Output: 1A
• Frequency - Switching: 1.5MHz
• Voltage - Input: 2.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 6-WDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

RT8010/A
2. I
internal switches, R
continuous mode, the average output current flowing
through inductor L is “chopped” between the main switch
and the synchronous switch. Thus, the series resistance
looking into the LX pin is a function of both top and bottom
MOSFET R
R
The R
obtained from the Typical Performance Characteristics
curves. Thus, to obtain I
and multiply the result by the square of the average output
current.
Other losses including C
losses and inductor core losses generally account for less
than 2% of the total loss.
Thermal Considerations
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, T
the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT8010/A DC/DC converter, where T
junction temperature of the die 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.
The maximum power dissipation at T
calculated by following formula :
P
WDFN-6L 2x2 packages
The maximum power dissipation depends on operating
ambient temperature for fixed T
resistance θ
www.richtek.com
12
D(MAX)
SW
D(MAX)
2
R losses are calculated from the resistances of the
= R
DS(ON)
= (T
DS(ON)TOP
= (125°C − 25°C) / 120°C/W = 0.833W for
J(MAX)
DS(ON)
J(MAX)
for both the top and bottom MOSFETs can be
JA
JA
.
A
is layout dependent. For WDFN-6L 2x2
is the ambient temperature and the θ
is the maximum operation junction
− T
and the Duty Cycle (DC) as follows :
x DC + R
A
) / θ
SW
2
R losses, simply add R
JA
and external inductor R
IN
DS(ON)BOT
and C
OUT
JA
J(MAX)
J(MAX)
x (1 − DC)
is 120°C/W on the
A
A
ESR dissipative
is the maximum
= 25°C can be
is the maximum
and thermal
SW
to R
L
JA
. In
is
L
For RT8010/A packages, the Figure 5 of derating curves
allows the designer to see the effect of rising ambient
temperature on the maximum power allowed.
Checking Transient Response
The regulator loop response can be checked by looking
at the load transient response. Switching regulators take
several cycles to respond to a step in load current. When
a load step occurs, V
equal to ΔI
resistance of C
discharge C
by the regulator to return V
During this recovery time, V
overshoot or ringing that would indicate a stability problem.
Layout Considerations
Follow the PCB layout guidelines for optimal performance
of RT8010/A.
For the main current paths as indicated in bold lines in
Figure 6, keep their traces short and wide.
Put the input capacitor as close as possible to the device
pins (VIN and GND).
LX node is with high frequency voltage swing and should
be kept small area. Keep analog components away from
LX node to prevent stray capacitive noise pick-up.
Connect feedback network behind the output capacitors.
Keep the loop area small. Place the feedback
components near the RT8010/A.
Figure 5. Derating Curves for RT8010/A Package
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
WDFN-6L 2x2
LOAD
OUT
(ESR), where ESR is the effective series
generating a feedback error signal used
OUT
25
Ambient Temperature (°C)
. ΔI
OUT
LOAD
immediately shifts by an amount
50
OUT
DS8010/A-06 February 2011
also begins to charge or
WQFN-16L 3x3
OUT
to its steady-state value.
can be monitored for
75
Four Layers PCB
100
125