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PDF RT8016 Data sheet ( Hoja de datos )
| Número de pieza | RT8016 | |
| Descripción | High Efficiency PWM Step-Down DC/DC Converter | |
| Fabricantes | Richtek | |
| Logotipo |  |
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®
RT8016
1.5MHz, 1A, High Efficiency PWM Step-Down DC/DC
Converter
General Description
Features
The RT8016 is a high-efficiency Pulse-Width-Modulated
(PWM) step-down DC-DC converter. Capable of delivering
1A output current over a wide input voltage range from
2.5V to 5.5V, the RT8016 is ideally suited for portable
electronic devices that are powered from 1-cell Li-ion
battery or from other power sources such as cellular
phones, PDAs and hand-held devices.
Two operating modes are available including : PWM/Low-
Dropout autoswitch and shut-down modes, the Internal
synchronous rectifier with low RDS(ON) dramatically reduces
conduction loss at PWM mode. No external Schottky
diode is required in practical application.
The RT8016 enters Low-Dropout mode when normal PWM
cannot provide regulated output voltage by continuously
turning on the upper PMOS. The RT8016 enters shut-
down mode and consumes less than 0.1uA when EN pin
is pulled low. The RT8016 also offers a range of 1V to
3.3V with 0.1V per step or adjustable output voltage by
two external resistor.
The switching ripple is easily smoothed-out by small
package filtering elements due to a fixed operating
frequency of 1.5MHz. This along with small WDFN-6L 2x2
package provides small PCB area application. Other
features include soft start, lower internal reference voltage
with 2% accuracy, over temperature protection, and over
current protection.
Pin Configurations
(TOP VIEW)
GND 1
EN 2
VIN 3
6 FB/VOUT
5 GND
7 4 LX
WDFN-6L 2x2
+2.5V to +5.5V Input Range
Adjustable Output From 0.6V to VIN
1A Output Current
95% Efficiency
No Schottky Diode Required
1.5MHz Fixed Frequency PWM Operation
Small 6-Lead WDFN Package
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Mobile Phones
Personal Information Appliances
Wireless and DSL Modems
MP3 Players
Portable Instruments
Ordering Information
RT8016-
Package Type
QW : WDFN-6L 2x2 (W-Type)
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Output Voltage
Default : Adjustable
10 : 1.0V
11 : 1.1V
:
32 : 3.2V
33 : 3.3V
Note :
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
DS8016-04 February 2012
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
1 page  
RT8016
Parameter
Symbol
Test Conditions
Min Typ Max Unit
EN Low-Level Input Voltage
VEN_L
Under Voltage Lock Out threshold UVLO
-- -- 0.4 V
-- 1.8 --
V
Hysteresis
-- 0.1 --
V
Oscillator Frequency
Thermal Shutdown Temperature
Max. Duty Cycle
fOSC
TSD
VIN = 3.6V, IOUT = 100mA
1.2 1.5
-- 160
100 --
1.8 MHz
-- °C
-- %
LX Current Source
Minimum On-Time
VIN = 3.6V, VLX = 0V or VLX = 3.6V
1
-- 100 μA
tON -- 120 140 ns
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 single-layer and four-layer test board of JEDEC 51. The measurement case position
of θJC is on the lead 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.
Note 5. ΔV = IOUT x PRDS(ON)
Note 6. Guarantee by design.
Note 7. The start up time is about 300μs.
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
DS8016-04 February 2012
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5
5 Page 
The output ripple is highest at maximum input voltage
since ΔIL increases with input voltage. Multiple capacitors
placed in parallel may be needed to meet the ESR and
RMS current handling requirements. Dry tantalum, special
polymer, aluminum electrolytic and ceramic capacitors are
all available in surface mount packages. Special polymer
capacitors offer very low ESR but have lower capacitance
density than other types. Tantalum capacitors have the
highest capacitance density but it is important to only
use types that have been surge tested for use in switching
power supplies. Aluminum electrolytic capacitors have
significantly higher ESR but can be used in cost-sensitive
applications provided that consideration is given to ripple
current ratings and long term reliability. Ceramic capacitors
have excellent low ESR characteristics but can have a
high voltage coefficient and audible piezoelectric effects.
The high Q of ceramic capacitors with trace inductance
can also lead to significant ringing.
Using Ceramic Input and Output Capacitors
Higher values, lower cost ceramic capacitors are now
becoming available in smaller case sizes. Their high ripple
current, high voltage rating and low ESR make them ideal
for switching regulator applications. However, care must
be taken when these capacitors are used at the input and
output. When a ceramic capacitor is used at the input
and the power is supplied by a wall adapter through long
wires, a load step at the output can induce ringing at the
input, VIN. At best, this ringing can couple to the output
and be mistaken as loop instability. At worst, a sudden
inrush of current through the long wires can potentially
cause a voltage spike at VIN large enough to damage the
part.
Output Voltage Programming
The resistive divider allows the FB pin to sense a fraction
of the output voltage as shown in Figure 4.
VOUT
FB
RT8016
GND
R1
R2
RT8016
For adjustable voltage mode, the output voltage is set by
an external resistive divider according to the following
equation :
VOUT = VREF(1+ RR21)
where VREF is the internal reference voltage (0.6V typ.)
Efficiency Considerations
The efficiency of a switching regulator is equal to the output
power divided by the input power times 100%. It is often
useful to analyze individual losses to determine what is
limiting the efficiency and which change would produce
the most improvement. Efficiency can be expressed as :
Efficiency = 100% − (L1+ L2+ L3+ ...)
where L1, L2, etc. are the individual losses as a percentage
of input power. Although all dissipative elements in the
circuit produce losses, two main sources usually account
for most of the losses : VIN quiescent current and I2R
losses.
The VIN quiescent current loss dominates the efficiency
loss at very low load currents whereas the I2R loss
dominates the efficiency loss at medium to high load
currents. In a typical efficiency plot, the efficiency curve
at very low load currents can be misleading since the
actual power lost is of no consequence.
1. The VIN quiescent current appears due to two factors
including : the DC bias current as given in the electrical
characteristics and the internal main switch and
synchronous switch gate charge currents. The gate charge
current results from switching the gate capacitance of the
internal power MOSFET switches. Each time the gate is
switched from high to low to high again, a packet of charge
ΔQ moves from VIN to ground.
The resulting ΔQ/Δt is the current out of VIN that is typically
larger than the DC bias current. In continuous mode,
IGATECHG = f(QT+QB)
where QT and QB are the gate charges of the internal top
and bottom switches. Both the DC bias and gate charge
losses are proportional to VIN and thus their effects will
be more pronounced at higher supply voltages.
Figure 4. Setting the Output Voltage
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
DS8016-04 February 2012
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
11
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet RT8016.PDF ] | |
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