RT6154A/B

®
RT6154A/B
High Efficiency Single Inductor Buck-Boost Converter
General Description
Features
The RT6154A/B is a high efficiency single inductor BuckBoost Converter which can operate with wide input voltage
such as battery which is higher or lower than the output
voltage and it can supply the load current up to 4A. The
maximum peak current in the switches is limited to a
typical value of 5A.
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Operates from a Single Li-ion Cell : 1.8V to 5.5V
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Adjustable Output Voltage : 1.8V to 5.5V
3A Maximum Load Capability for V IN > 3.6V,
VOUT = 3.3V
Power Save Mode (PSM) for Improving Low Output
Power Efficiency
Fixed Frequency Operation at 2.4MHz and
Synchronization Possible from 2.2MHz to 2.6MHz
Up to 96% Efficiency
Input Current Limit
Internal Compensation
RoHS Compliant and Halogen Free
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The RT6154A/B feedback loop is internally compensated
for both Buck and Boost operation and it provides seamless
transition between Buck and Boost modes and optimal
transient response. The RT6154A/B operates at 2.4MHz
typical switching frequency in full synchronous operation.
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The RT6154A/B operates in Pulse Skipped Modulation
(PSM) mode for increasing efficiency during low power
RF transmission modes. The Power Save Mode can be
disabled, forcing the RT6154A/B to operate at a fixed
switching frequency operation at 2.4MHz. The RT6154A/
B can also be synchronized with external frequency from
2.2MHz to 2.6MHz. The RT6154A output voltage is
programmable using an external resistor divider, and the
RT6154B is fixed internally to 3.3V.
Applications
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Cellular Phones
Portable Hard Disk Drives
PDAs
Pin Configurations
(TOP VIEW)
VINA
GND
FB
VOUT
VOUT
LX2
LX2
1
2
3
4
5
6
7
PGND
15
14
13
12
11
10
9
8
PGOOD
PS/SYNC
EN
VIN
VIN
LX1
LX1
WDFN-14AL 4x3
Simplified Application Circuit
LX1
LX2
RT6154A
VIN
VOUT
VIN
VINA
Enable
EN
VOUT
FB
PGOOD
Power Good
Output
PS/SYNC
GND
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RT6154A/B
Ordering Information
Marking Information
RT6154A/B
RT6154AGQW
Package Type
QW : WDFN-14AL 4x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
0E= : Product Code
0E=YM
DNN
YMDNN : Date Code
RT6154A Adjustable Output Voltage
RT6154B Fixed 3.3V Output Voltage
RT6154BGQW
Note :
0D= : Product Code
Richtek products are :
`
RoHS compliant and compatible with the current require-
`
Suitable for use in SnPb or Pb-free soldering processes.
0D=YM
DNN
YMDNN : Date Code
ments of IPC/JEDEC J-STD-020.
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
VINA
Supply Voltage Input.
2
GND
Analog Ground.
3
FB
Voltage Feedback of Adjustable Versions, must be connected to VOUT on
fixed output voltage versions.
4, 5
VOUT
Buck-Boost Converter Output.
6, 7
LX2
Second Switch Node.
8, 9
LX1
First Switch Node.
10, 11
VIN
Power Input.
12
EN
Enable Control Input (1 Enabled, 0 Disabled). Must not be left open.
13
PS/SYNC
Enable/Disable Control Input for Power Save Mode (1 disabled, 0 enabled,
clock signal for synchronization). Must not be left open.
14
PGOOD
Power Good Indicator Output. (1 good, 0 failure; open drain).
PGND
Power Ground. The exposed pad must be soldered to a large PCB and
connected to PGND for maximum power dissipation.
15
(Exposed Pad)
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RT6154A/B
Function Block Diagram
RT6154A (Adjustable Output Voltage)
LX2
LX1
VIN
VOUT
Gate DRV
VINA
OCP
PWM
CTRL
-
EN
Digital
CTRL
FB
AMP
+
PS/SYNC
PGOOD
VREF
PGND
OSC
OTP
GND
UVLO
RT6154B (Fixed 3.3V Output Voltage)
LX1
LX2
VIN
VOUT
Gate DRV
VINA
OCP
PWM
CTRL
EN
RFB1
Digital
CTRL
-
AMP
+
PS/SYNC
FB
RFB2
PGOOD
VREF
PGND
GND
OSC
OTP
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RT6154A/B
Operation
The RT6154A/B is a synchronous current-mode switching
Buck-Boost converter designed to an adjustable output
voltage from an input supply that can be above, equal, or
below the output voltage. The average inductor current is
regulated by a fast current regulator which is controlled
by a voltage control loop. The voltage error amplifier gets
its feedback input from the FB pin. The output voltage of
the RT6154A is adjustable, and can be set by the external
divider resistor value. For the RT6154B, the output voltage
is fixed at 3.3V. When VIN is greater than VOUT, the
device operates in Buck mode. When VIN is lower than
VOUT, the device operates in Boost mode. When VIN is
close to VOUT, the RT6154A/B automatically enters Buck
or Boost mode. In that case, the converter will maintain
the regulation for output voltage and keep a minimum
current ripple in the inductor to guarantee good
performance.
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RT6154A/B
Absolute Maximum Ratings
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(Note 1)
VIN, VINA to GND ------------------------------------------------------------------ −0.2V to 6V
VOUT to GND ----------------------------------------------------------------------- −0.2V to 6.5V
EN, PS/SYNC to GND ------------------------------------------------------------ −0.2V to (PVIN + 0.2V) with 6V max.
FB to PGND ------------------------------------------------------------------------- −0.2V to (PVIN + 0.2V) with 6V max.
LX1 ------------------------------------------------------------------------------------- (PGND − 0.2V) to (PVIN + 0.2V) with 6V max.
LX2 ------------------------------------------------------------------------------------- (PGND − 0.2V) to (PVIN + 0.2V) with 6.5V max.
Power Dissipation, PD @ TA = 25°C
WDFN-14AL 4x3 -------------------------------------------------------------------- 3.49W
Package Thermal Resistance (Note 2)
WDFN-14AL 4x3, θJA -------------------------------------------------------------- 28.6°C/W
WDFN-14AL 4x3, θJC -------------------------------------------------------------- 3.2°C/W
Lead Temperature (Soldering, 10 sec.) ---------------------------------------- 260°C
Junction Temperature -------------------------------------------------------------- 150°C
Storage Temperature Range ----------------------------------------------------- −65°C to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Model) ------------------------------------------------------- 2kV
MM (Machine Model) -------------------------------------------------------------- 200V
Recommended Operating Conditions
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(Note 4)
Input Voltage Range --------------------------------------------------------------- 1.8V to 5.5V
Output Voltage Range ------------------------------------------------------------- 1.8V to 5.5V
Junction Temperature Range ----------------------------------------------------- −40°C to 125°C
Ambient Temperature Range ----------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VIN = 3.6V, TA = 25°C, unless otherwise specified.)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Under-Voltage Lockout Rising
UVLO_R
Threshold
1.6
1.7
1.8
V
Under-Voltage Lockout
Falling Threshold
1.5
1.6
1.7
V
1.5
1.8
2.0
V
UVLO_F
Minimum Input Voltage for
Start-Up
FB Voltage
VFB
Force PWM (RT6154A)
0.495
0.5
0.505
V
VOUT Voltage
VOUT
Force PWM (RT6154B)
3.267
3.3
3.333
V
Shutdown Current
ISHDN
EN = 0V, PS/SYNC = 0V,
PGOOD = 0V
--
0.1
1
μA
Switching Frequency
fSW
2.2
2.4
2.6
MHz
2.2
2.4
2.6
MHz
VIN = VINA = 3.6V
--
5
--
A
High-Side Switch RDS(ON)
VIN = VINA = 3.6V
--
50
--
mΩ
Low-Side Switch RDS(ON)
VIN = VINA = 3.6V
--
50
--
mΩ
Frequency Range for
Synchronization
Current Limit
IOC
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RT6154A/B
Parameter
Symbol
Quiescent Current
Test Conditions
Min
Typ
Max
Unit
Non Switching, EN = VINA,
SYNC = 0V
--
20
40
μA
FB Input Leakage
IFB
ADJ Mode
−1
--
1
μA
Leakage of LX1 and LX2
ILX1
ILX2
All Switch Off
--
--
5
μA
Line Regulation
ΔVOUT, LINE
FPWM
--
0.5
--
%
Load Regulation
ΔVOUT, LOAD FPWM
--
0.5
--
%
EN, PS/SYNC Logic-High
Input Voltage Logic-Low
VIH
1.2
--
--
VIL
--
--
0.4
PS/SYNC Input Current
--
0.1
1
μA
EN Pull Low Resistance
--
150
--
kΩ
--
0.04
0.4
V
--
0.01
0.1
μA
PGOOD Output Low Voltage
VOUT = 3.3V, IPGOODL = 10μA
PGOOD Output Leakage
Current
V
Output Over-Voltage
Protection
VOUTOVP
--
6.2
--
V
Thermal Shutdown
TSD
--
160
--
°C
Thermal Shutdown
Hysteresis
ΔTSD
--
30
--
°C
Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and 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 may
affect device reliability.
Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is
measured at the exposed pad of the package.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
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RT6154A/B
Typical Application Circuit
RT6154A (Adjustable Output Voltage)
L1
2.2µH
8, 9
6, 7
LX1
LX2
RT6154A
10, 11
4, 5
VOUT
VIN
C1
R1
20µF
1M
1
3
R3
FB
VINA
C3
1M
R2
0.1µF
180k
VIN
Enable
12
13
EN
PGOOD
VOUT
C2
100µF
Power Good
Output
14
PS/SYNC
GND
2
PGND
15 (Exposed Pad)
RT6154B (Fixed 3.3V Output Voltage)
L1
2.2µH
8, 9
6, 7
LX1
LX2
RT6154B
10, 11
4, 5
VOUT
VIN
C1
20µF
1
3
FB
VINA
C3
0.1µF
VIN
Enable
12
13
EN
R1
1M
Power Good
Output
14
PS/SYNC
GND
2
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PGOOD
VOUT
C2
100µF
PGND
15 (Exposed Pad)
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RT6154A/B
Typical Operating Characteristics
Efficiency vs. Output Current
Efficiency vs. Output Current
100
100
90
90
VIN = 3.7V
VIN = 2.8V
VIN = 5V
70
VIN = 3.7V
VIN = 2.8V
VIN = 5V
80
Efficiency (%)
Efficiency (%)
80
60
50
40
30
20
70
60
50
40
30
20
VOUT = 3.3V
Power Save Enable
10
0
0.01
0.1
1
VOUT = 3.3V
Power Save Disable
10
0
0.01
10
Output Current (A)
Efficiency vs. Output Current
10
Efficiency vs. Output Current
100
90
90
VIN = 5V
VIN = 3.7V
VIN = 2.8V
70
VIN = 5V
VIN = 3.7V
VIN = 2.8V
80
Efficiency (%)
80
Efficiency (%)
1
Output Current (A)
100
60
50
40
30
20
70
60
50
40
30
20
VOUT = 4.5V
Power Save Enable
10
0
0.01
0.1
1
VOUT = 4.5V
Power Save Disable
10
0
0.01
10
Output Current (A)
0.1
1
10
Output Current (A)
Output Voltage vs. Output Current
Output Voltage vs. Output Current
3.40
4.60
3.35
4.55
Output Voltage (V)
Output Voltage (V)
0.1
3.30
3.25
4.50
4.45
VIN = 3.7V, VOUT = 4.5V
Power Save Disable
VIN = 3.7V, VOUT = 3.3V
Power Save Disable
3.20
4.40
0.01
0.1
1
Output Current (A)
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10
0.01
0.1
1
10
Output Current (A)
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RT6154A/B
Load Transient Response
Maximum Output Current vs. Input Voltage
Maximum Output Current (A)1
5
4
3
I LOAD
(500mA/Div)
2
VOUT
(100mV/Div)
1
VOUT = 3.3V
VIN = 2.8V, ILOAD = 500mA to 1500mA
0
1.8
2.2
2.6
3
3.4
3.8
4.2
4.6
5
5.4
Time (50μs/Div)
5.8
Input Voltage (V)
Load Transient Response
Line Transient Response
I LOAD
(500mA/Div)
VOUT
(100mV/Div)
VIN = 4.2V, ILOAD = 500mA to 1500mA
VOUT
(50mV/Div)
VIN
(1V/Div)
VIN = 3V to 3.7V, ILOAD = 500mA
Time (50μs/Div)
Time (500μs/Div)
Line Transient Response
Startup After Enable
VENB
(2V/Div)
VOUT
(2V/Div)
I IN
(1A/Div)
VOUT
(50mV/Div)
VIN
(1V/Div)
VLX2
(5V/Div)
VIN = 3V to 3.7V, ILOAD = 1A
Time (500μs/Div)
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VIN = 1.8V, RL = 8.2Ω
Time (100μs/Div)
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RT6154A/B
Startup After Enable
VENB
(5V/Div)
VOUT
(2V/Div)
I IN
(1A/Div)
VLX1
(5V/Div)
VIN = 5.5V, RL = 8.2Ω
Time (100μs/Div)
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RT6154A/B
Application Information
The RT6154A/B Buck-Boost DC/DC converter can operate
with wide input voltage such as battery which is higher or
lower than the output voltage and it can supply the load
current up to 4A. The maximum peak current in the
switches is limited to a typical value of 5A. The typical
operating input voltage is between 1.8V and 5.5V. The
RT6154A output voltage can be set from 1.8V to 5.5V by
changing the external divider resistor on the FB pin for
the adjustable. The RT6154B output voltage is fixed to
3.3V. The converter feedback loop is internally
compensated for both Buck and Boost operation and it
provides seamless transition between Buck and Boost
modes operation.
Power Good
The RT6154A/B has a built-in power good function on
PGOOD pin to indicate whether the output voltage is
regulated properly or not. The PGOOD pin output is opendrain, so the logic function can be adjusted to any voltage
level by connecting a pull-up resistor to the supply voltage.
When the output voltage is regulated properly, the PGOOD
pin becomes high impedance and indicates high level to
the power good output. When the output voltage is
regulated improperly, the PGOOD pin becomes low
impedance and indicates low level to the power good
output.
Power-Save Mode and Synchronization
Enable
The PS/SYNC pin can be used to select different operation
The device can be enabled or disenabled by the EN pin.
When the EN pin is higher than the threshold of logic
high, the device starts operation with soft-start. Once the
EN pin is set at low, the device will be shut down. In
shutdown mode, the converter stops switching, internal
control circuitry is turned off, and the load is disconnected
from the input. This also means that the output voltage
can drop below the input voltage during shutdown.
modes. When PS/SYNC is set low and the average
inductor current gets lower then about 400mA, Power Save
Mode can be enabled and used to improve efficiency.
Output Voltage Setting
The RT6154A output voltage can be set from 1.8V to 5.5V
by changing the external divider resistor on the FB pin.
The RT6154B output voltage is fixed to 3.3V. When the
adjustable output voltage version is used, the resistor
divider must be connected between VOUT, FB and GND.
The typical value of the voltage at the FB pin is 500mV
and the RT6154A output voltage can be set from 1.8V to
5.5V. It is recommended to keep the resistor R2 value in
the range of 200kΩ. From that, the value of the resistor
connected between VOUT and FB, R1, depending on the
needed output voltage, can be calculated as following
equation :
V
R1 = R2 × ⎛⎜ OUT − 1⎞⎟
⎝ VFB
⎠
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At this point the converter operates with reduced switching
frequency and with a minimum quiescent current to
maintain high efficiency. When the load increases above
the minimum forced inductor current of about 400mA, the
device will automatically switch to PWM mode. The Power
Save Mode can be disabled by programming the PS/SYNC
high. Connecting a clock signal at PS/SYNC can force
the RT6154A/B switching frequency to synchronize to the
connected clock frequency. The PS/SYNC input supports
standard logic thresholds and the frequency range is
between 2.2MHz to 2.6MHz.
Dynamic Current Limit
To protect the device and the application, the peak inductor
current is limited internally on the IC. At nominal operating
conditions, this current limit is constant. The current limit
value can be found in the electrical characteristics table.
If the supply voltage at VIN drops below 2.3V, the current
limit is reduced. This can happen when the input power
source becomes weak. Increasing output impedance, when
the batteries are almost discharged, or an additional heavy
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RT6154A/B
pulse load is connected to the battery can cause the VIN
voltage to drop. The dynamic current limit has its lowest
value when reaching the minimum recommended supply
voltage at VIN.
Soft-Start and Short Circuit Protection
After being enabled, the device starts operating. The
current limit ramps up from an initial 1A following the output
voltage increasing. At an output voltage of about 1.2V, the
current limit is at its nominal value. If the output voltage
does not increase, the current limit will not increase. There
is no timer implemented. Thus, the output voltage
overshoot at startup, as well as the inrush current, is kept
at a minimum. The device ramps up the output voltage in
a controlled manner even if a large capacitor is connected
at the output. When the output voltage does not increase
above 1.2V, the device assumes a short circuit at the
output, and keeps the current limit low to protect itself
and the application. At a short on the output during
operation, the current limit also is decreased accordingly.
Protection
Additional protections of the RT6154A/B include current
overload protection, output over-voltage clamp, and thermal
shutdown. To protect the device from overheating, the
device has a built-in temperature sensor which monitors
the internal junction temperature. If the temperature
exceeds a threshold, the device stops operating. As soon
as the IC temperature decreases below the threshold with
a hysteresis, it starts operating again. The built-in
hysteresis is designed to avoid unstable operation at IC
temperatures near the over-temperature threshold.
Under-Voltage Lockout
The under-voltage lockout circuit prevents the device from
operating incorrectly at low input voltages. It prevents the
converter from turning on the power switches under
undefined conditions and prevents the battery from deep
discharge. PVIN voltage must be greater than 1.7V to
enable the converter. During operation, if PVIN voltage
drops below 1.6V, the converter is disabled until the supply
exceeds the UVLO rising threshold. The RT6154A/B
automatically restarts if the input voltage recovers to the
input voltage UVLO high level.
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Inductor Selection
To properly configure the Buck-Boost converter, an
inductor must be connected between the LX1 and LX2
pins. To estimate the inductance value, two equations are
listed as below :
VOUT × ( VIN(MAX) − VOUT )
L1 >
(H)
f × ΔIL × VIN(MAX)
L2 >
VIN(MIN) × ( VOUT − VIN(MIN) )
f × ΔIL × VOUT
(H)
where f is the minimum switching frequency. L1 is the
minimum inductor value for Buck mode operation. VIN(MAX)
is the maximum input voltage. L2 is the minimum
inductance for Boost mode operation. VIN(MIN) is the
minimum input voltage. The recommended minimum
inductor value is either L1 or L2 whichever is higher. For
example, a suitable inductor value is 2.2μH for generating
a 3.3V output voltage from a Li-Ion battery with the range
from 2.5V to 4.2V. The recommended inductor value range
is between 1.5μH and 4.7μH. In general, a higher inductor
value offers better performance in high voltage conversion
condition.
Table 1. Inductor Suggestion
Vendor
Inductor Series
Taiyo Yuden
NRS5024T2R2NMGJ
Output Capacitor Selection
The output capacitor selection determines the output
voltage ripple and transient response. It is recommended
to use ceramic capacitors placed as close as possible to
the VOUT and GND pins of the IC. If, for any reason, the
application requires the use of large capacitors which can
not be placed close to the IC, using a small ceramic
capacitor in parallel to the large one is recommended.
This small capacitor should be placed as close as possible
to the VOUT and GND pins of the IC. The output voltage
ripple for a given output capacitor is expressed as follows :
ΔVOUT , peak (Buck) =
VOUT × (VIN − VOUT )
VIN × 8 × L × (fOSC )2 × COUT
I
× (VOUT − VIN )
ΔVOUT , peak (Boost) = LOAD
COUT × VOUT × fOSC
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RT6154A/B
The maximum voltage of overshoot or undershoot, is
inversely proportional to the value of the output capacitor.
To ensure stability and excellent transient response, it is
recommended to use a minimum of 100μF X7R capacitors
at the output. For surface mount applications, Taiyo Yuden
or TDK ceramic capacitors, X7R series Multi-layer Ceramic
Capacitor is recommended.
A capacitor with a value in the range of the calculated
minimum should be used. This is required to maintain
control loop stability. There are no additional requirements
regarding minimum ESR. Low ESR capacitors should be
used to minimize output voltage ripple. Larger capacitors
will cause lower output voltage ripple as well as lower
output voltage drop during load transients.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
dissipation depends on the thermal resistance of the IC
package, PCB layout, rate of surrounding airflow, and
difference between junction and ambient temperature. The
maximum power dissipation can be calculated by the
following formula :
The maximum power dissipation depends on the operating
ambient temperature for fixed T J(MAX) and thermal
resistance, θJA. The derating curve in Figure 1 allows the
designer to see the effect of rising ambient temperature
on the maximum power dissipation.
4.0
Maximum Power Dissipation (W)1
If the RT6154A/B operates in Buck mode, the worst-case
voltage ripple occurs at the highest input voltage. When
the RT6154A/B operates in Boost mode, the worst-case
voltage ripple occurs at the lowest input voltage.
Four-Layer PCB
3.6
3.2
2.8
2.4
2.0
1.6
1.2
0.8
0.4
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 1. Derating Curve of Maximum Power Dissipation
Layout Consideration
For the best performance, the following PCB Layout
guidelines must be strictly followed.
`
Place the input and output capacitors as close as
possible to the input and output pins.
`
Keep the main power traces as wide and short as
possible.
PD(MAX) = (TJ(MAX) − TA) / θJA
`
where TJ(MAX) is the maximum junction temperature, TA is
the ambient temperature, and θJA is the junction to ambient
thermal resistance.
Connect the GND and Exposed Pad to a strong ground
plane for maximum thermal dissipation and noise
protection.
`
Switch node experiences high frequency voltage swings
and should be kept in a small area. Keep analog
components away from the switch node to prevent stray
capacitive noise pick-up.
For recommended operating condition specifications, the
maximum junction temperature is 125°C. The junction to
ambient thermal resistance, θJA, is layout dependent. For
WDFN-14AL 4x3 package, the thermal resistance, θJA, is
28.6°C/W on a standard JEDEC 51-7 four-layer thermal
test board. The maximum power dissipation at TA = 25°C
can be calculated by the following formula :
PD(MAX) = (125°C − 25°C) / (28.6°C/W) = 3.49W for
WDFN-14AL 4x3 package
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
DS6154A/B-01 May 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
13
RT6154A/B
Figure 2. PCB Layout Guide
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
www.richtek.com
14
is a registered trademark of Richtek Technology Corporation.
DS6154A/B-01 May 2014
RT6154A/B
Outline Dimension
2
1
2
1
DETAIL A
Pin #1 ID and Tie Bar Mark Options
Note : The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min.
Max.
Min.
Max.
A
0.700
0.800
0.028
0.031
A1
0.000
0.050
0.000
0.002
A3
0.175
0.250
0.007
0.010
b
0.200
0.300
0.008
0.012
D
3.900
4.100
0.154
0.161
D2
2.800
2.900
0.110
0.114
E
2.900
3.100
0.114
0.122
E2
1.530
1.630
0.060
0.064
e
0.500
0.020
e1
0.460
0.018
K
0.150
0.250
0.006
0.010
L
0.350
0.450
0.014
0.018
W-Type 14AL DFN 4x3 Package
Richtek Technology Corporation
14F, No. 8, Tai Yuen 1st Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789
Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should
obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot
assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be
accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.
DS6154A/B-01 May 2014
www.richtek.com
15