|
|
PDF RT8058A Data sheet ( Hoja de datos )
| Número de pieza | RT8058A | |
| Descripción | High Efficiency PWM Step-Down DC/DC Converter | |
| Fabricantes | Richtek | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de RT8058A (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
|
No Preview Available !
RT8058A
1.2MHz, 2A, High Efficiency PWM Step-Down
DC/DC Converter
General Description
The RT8058Ais a current mode PWM step-down converter.
The chip is ideal for fixed frequency and low ripple
applications over full range of load conditions. Its input
voltage range is from 2.6V to 5.5V with a constant 1.2MHz
switching frequency that allows it to adopt tiny, low cost
capacitors and inductors with 2mm or less in height making
it ideal for single-cell Li-lon/polymer battery applications.
The low on resistance internal MOSFET can achieve high
efficiency without the need of external schottky diodes in
wide operating ranges and the output voltage is adjustable
from 0.6V to 5V that can provide up to 2A load current.
The RT8058A operates at 100% duty cycle for low dropout
operation that extends battery life in portable devices.
The RT8058A is available in a WDFN-10L 3x3 package.
Features
z 0.6V Reference Allows Low Output Voltage
z Low Dropout Operation : 100% Duty Cycle
z 2A Load Current
z <2μA Shutdown Current
z Up to 95% Efficiency
z No Schottky Diode Required
z 1.2MHz Constant Switching Frequency
z Low RDS(ON) Internal Switches
z Internally Compensated
z Internal Soft-Start
z Over temperature Protection
z Short Circuit Protection
z Small 10-Lead WDFN Package
z RoHS Compliant and Halogen Free
Ordering Information
RT8058A
Package Type
QW : WDFN-10L 3x3 (W-Type)
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
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
E9= : Product Code
E9=YM
DNN
YMDNN : Data Code
Applications
z Portable Instruments
z Microprocessors and DSP Core supplies
z Cellular Telephones
z Wireless and DSL Modems
z Digital Cameras
z PC Cards
Pin Configurations
(TOP VIEW)
PGND 1
PGND 2
FB 3
GND 4
POK 5
GND
11
10 LX
9 LX
8 PVDD
7 VDD
EN
WDFN-10L 3x3
DS8058A-02 April 2011
www.richtek.com
1
1 page  
Typical Operating Characteristics
100
90
80
70
60
50
40
30
20
10
0
0
Efficiency vs. Output Current
VIN = 5V
VIN = 3.3V
VOUT = 1.2V, L = 3.3μH, COUT = 22μF
0.25 0.5 0.75 1 1.25 1.5 1.75
Output Current (A)
2
1.200
1.199
1.198
1.197
1.196
1.195
1.194
1.193
1.192
1.191
1.190
2.5
Output Voltage vs. Input Voltage
IOUT = 0A
3 3.5 4 4.5 5 5.5
Input Voltage (V)
Switching Frequency vs. Input Voltage
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
VOUT = 1.2V, IOUT = 300mA
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
DS8058A-02 April 2011
RT8058A
Output Voltage vs. Output Current
1.196
1.195
1.194
1.193
1.192
1.191
VIN = 5V
VIN = 3.3V
1.190
1.189
1.188
0
VOUT = 1.2V, L = 3.3μH, COUT = 22μF
0.25 0.5 0.75 1 1.25 1.5 1.75
Output Current (A)
2
0.600
0.598
0.596
0.594
0.592
0.590
0.588
0.586
0.584
0.582
0.580
-50
FB Voltage vs. Temperature
VIN = 3.3V, IOUT = 0A
-25 0 25 50 75 100 125
Temperature (°C)
Switching Frequency vs. Temperature
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
-50
-25
VIN = 3.3V, VOUT = 1.2V, IOUT = 300mA
0 25 50 75
Temperature (°C)
100 125
www.richtek.com
5
5 Page 
The selection of COUT is determined by the Effective Series
Resistance (ESR) that is required to minimize voltage ripple
and load step transients, as well as the amount of bulk
capacitance that is necessary to ensure that the control
loop is stable. Loop stability can be checked by viewing
the load transient response as described in a later section.
The output ripple, ΔVOUT, is determined by :
ΔVOUT
≤
ΔIL
⎢⎣⎡ESR
+
1
8fCOUT
⎤
⎥⎦
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.
RT8058A
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, VOUT immediately shifts by an amount
equal to ΔILOAD(ESR), where ESR is the effective series
resistance of COUT. ΔILOAD also begins to charge or
discharge COUT generating a feedback error signal used
by the regulator to return VOUT to its steady-state value.
During this recovery time, VOUT can be monitored for
overshoot or ringing that would indicate a stability problem.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature. 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 :
PD(MAX) = ( TJ(MAX) − TA ) / θJA
Where TJ(MAX) is the maximum operation junction
temperature, TA is the ambient temperature and the θJA is
the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT8058A, The maximum junction temperature is 125°C.
The junction to ambient thermal resistance θJA is layout
dependent. For WDFN-10L 3x3 packages, the thermal
resistance θJA is 70°C/W on the standard JEDEC 51-7
four layers thermal test board. The maximum power
dissipation at TA = 25°C can be calculated by following
formula :
PD(MAX) = (125°C − 25°C) / (70°C/W) = 1.429W for
WDFN-10L 3x3 packages
The maximum power dissipation depends on operating
ambient temperature for fixed TJ(MAX) and thermal
resistance θJA. For RT8058A packages, the Figure 2 of
derating curves allows the designer to see the effect of
rising ambient temperature on the maximum power
allowed.
DS8058A-02 April 2011
www.richtek.com
11
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet RT8058A.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| RT8058 | High Efficiency PWM Step-Down DC/DC Converter | Richtek |
| RT8058A | High Efficiency PWM Step-Down DC/DC Converter | Richtek |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |