GRM32ER71C226M [ORISTER]
2A, 20V, 400KHz DC/DC Asynchronous Step.Down Converter; 2A ， 20V ， 400KHz的DC / DC异步Step.Down转换器
| 型号： | GRM32ER71C226M |
| 厂家： | 
ORISTER CORPORATION |
| 描述： | 2A, 20V, 400KHz DC/DC Asynchronous Step.Down Converter |
| 文件： | 总11页 (文件大小：486K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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RS6515
2A, 20V, 400KHz DC/DC Asynchronous Step‐Down Converter
General Description
The RS6515 is a high‐efficiency asynchronous step‐down DC/DC converter that can deliver up to 2A output current from
4.75V to 20V input supply. The RS6515's current mode architecture and external compensation allow the transient
response to be optimized over a wide range of loads and output capacitors. Cycle‐by‐cycle current limit provides protection
against shorted outputs and soft‐start eliminates input current surge during start‐up.
The RS6515 also provides output under voltage protection and thermal shutdown protection. The low current (<30μA)
shutdown mode provides output disconnection, enabling easy power management in battery‐powered systems.
Features
Applications
● 2A Output Current
● Up to 93% Efficiency
● PC Motherboard, Graphic Card
● LCD Monitor
● Integrated 100mΩ Power MOSFET Switches
● Fixed 385KHz Frequency
● Cycle‐by‐Cycle Over Current Protection
● Thermal Shutdown function
● Set‐Top Boxes
● DVD‐Video Player
● Telecom Equipment
● ADSL Modem
● Wide 4.75V to 21V Operating Input Range
● Output Adjustable from 0.92V to 18V
● Programmable Under Voltage Lockout
● Available in an MSOP‐10(EP) Package
● RoHS Compliant and 100% Lead (Pb)‐Free and Green
(Halogen Free with Commercial Standard)
● Printer and other Peripheral Equipment
● Microprocessor core supply
● Networking power supply
● Pre‐Regulator for Linear Regulators
● Green Electronics/Appliances
Application Circuits
C5
L1 15uH
10nF
U1
OUTPUT
3.3V/2A
4
9
INPUT
4.75V to 21V
D1
IN
R1
5
SW
FB
B340A
OFF
ON
25.8KΩ 1%
EN
SS
C1
C2
10uF/35V
CERAMIC x2
10
6
7
(Optional)
C3
C6
R3
5.6KΩ
8
C4
R2
22uF/6.3V
CERAMIC x2
GND COMP
10KΩ 1%
0.1uF
RS6515‐ADMS
8.2nF
This integrated circuit can be damaged by ESD. Orister Corporation recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
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C5
L1 15uH
D1
B340A
10nF
U1
OUTPUT
3.3V/2A
2
7
8
4
INPUT
IN
R1
4.75V to 21V
3
SW
FB
OFF
ON
25.8KΩ 1%
EN
SS
C1
10uF/35V
C2
5
6
CERAMIC x2
(Optional)
C6
C4
R2
22uF/6.3V
CERAMIC x2
GND COMP
C3
R3
10KΩ 1%
0.1uF
RS6508‐ADS
5.6KΩ
8.2nF
Pin Assignments
MSOP‐10(EP)
SOP‐8
PACKAGE
PIN
SYMBOL
NC
DESCRIPTION
1
‐
No Connect.
Bootstrap. This capacitor (C5) is needed to drive the power switch’s gate
above the supply voltage. It is connected between the SW and BS pins to
form a floating supply across the power switch driver. The voltage across
C5 is about 5V and is supplied by the internal +5V supply when the SW pin
voltage is low.
2
1
BS
3
4
‐
NC
IN
No Connect.
Supply Voltage. The RS6515 operates from a 4.75V to 20V unregulated
input. C1 is needed to prevent large voltage spikes from appearing at the
input.
2
MSOP‐10(EP)
Power Switching Output. SW is the switching node that supplies power to
the output. Connect the output LC filter from SW to the output load. Note
that a capacitor is required from SW to BS to power the high‐side switch.
Ground.
Feedback Input. FB senses the output voltage and regulates it. Drive FB
with a resistive voltage divider from the output voltage to ground. The
feedback threshold is 0.92V. See Setting the Output Voltage.
Compensation Node. COMP is used to compensate the regulation control
loop. Connect a series RC network from COMP to GND. In some cases, an
additional capacitor from COMP to GND is required. See Compensation.
Enable Input. EN is a digital input that turns the regulator on or off. Drive
EN high to turn on the regulator, drive it low to turn it off. For automatic
startup, leave EN unconnected.
5
3
4
5
SW
GND
FB
/
6,11
SOP‐8
7
8
6
COMP
9
7
8
EN
SS
Soft‐Start. Connect SS to an external capacitor to program the soft‐start. If
unused, leave it open.
10
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Ordering Information
DEVICE
DEVICE CODE
XX is nominal output voltage :
AD : ADJ
Y is package & Pin Assignments designator :
MS : MSOP‐10(EP) S : SOP‐8
RS6515‐XX Y Z
Z is Lead Free designator :
P: Commercial Standard, Lead (Pb) Free and Phosphorous (P) Free Package
G: Green (Halogen Free with Commercial Standard)
Block Diagram
Absolute Maximum Ratings
Symbol
VIN
VSW
VBS
VFB
VEN
VCOMP
VSS
Parameter
Supply Voltage
SW Pin Voltage
Boot Strap Voltage
Feedback Voltage
Range
‐0.3 to +21
‐0.3 to VIN +0.3
VSW ‐0.3 to VSW +6
‐0.3 to +6
‐0.3 to +6
‐0.3 to +6
‐0.3 to +6
150
Units
V
V
V
V
Enable/UVLO Voltage
Comp Voltage
V
V
V
SS Voltage
TJ
Junction Temperature
Operating Temperature Range
Storage Temperature Range
Lead Temperature
oC
oC
oC
oC
TOPR
TSTG
TLEAD
‐20 to +85
‐65 to +150
260
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Electrical Characteristics (VIN=12V, TA=25°C, unless otherwise specified)
Symbol
VIN
Parameter
Conditions
Min.
4.75
Typ.
‐
Max.
20
Unit
V
Input Voltage
‐
VFB
Feedback Voltage
4.75V ≤ VIN ≤ 21V
0.898 0.925 0.952
V
RDS(ON)1
RDS(ON)2
ISw
Upper Switch On Resistance
Lower Switch On Resistance
Upper Switch Leakage
‐
‐
‐
‐
‐
0.22
10
‐
‐
‐
10
‐
Ω
Ω
uA
A
VEN = 0V, VSW = 0V
ILIM
Current Limit (NOTE 1)
‐
3.0
‐
Current Sense Transconductance Output
Current to Comp Pin Voltage
Error Amplifier Voltage Gain
Error Amplifier Transconductance
Oscillator Frequency
Short Circuit Frequency
Soft‐Start Pin Equivalent Output Resistance
Maximum Duty Cycle
Minimum On Time
EN Shutdown Threshold
Enable Pull Up Current
EN UVLO Threshold Rising
EN UVLO Threshold Hysteresis
Supply Current (Shutdown)
Supply Current (Quiescent)
Thermal Shutdown
GCS
‐
‐
1.95
‐
‐
A/V
V/V
AVEA
GEA
FS
FOSC1
‐
DMAX
tON
‐
‐
‐
‐
ISD
IQ
‐
‐
‐
‐
400
830
400
240
9
550
‐
‐
‐
‐
‐
0.7
‐
2.35
‐
‐
‐
‐
1150 uA/V
‐
‐
‐
‐
‐
1.3
‐
2.65
‐
36
1.3
‐
KHz
KHz
KΩ
%
ns
V
uA
V
mV
uA
mA
oC
VFB = 0V
‐
VFB = 1.0V
‐
ICC＞100uA
VEN = 0V
VIN Rising
‐
VIN ≤0.4V
VEN ≥3V
‐
90
100
1.0
1.0
2.50
210
23
1.1
160
TSD
Notes:
1. Slope compensation changes current limit above 40% duty cycle.
2. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for
stress ratings. 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 for extended
periods may remain possibility to affect device reliability.
3. Devices are ESD sensitive. Handling precaution is recommended.
4. The device is not guaranteed to function outside its operating conditions.
5. θJA is measured in the natural convection at TA = 25°C on a high effective four layers thermal conductivity test board of
JEDEC 51‐7 thermal measurement standard.
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Detail Description
The RS6515 is a synchronous high voltage buck converter that can support the input voltage range from 4.75V to 20V and the
output current can be up to 2A.
Output Voltage Setting
The resistive divider allows the FB pin to sense the output voltage as shown in Figure 1.
Figure 1. Output Voltage Setting
The output voltage is set by an external resistive divider according to the following equation：
R1
R2
VOUT VFB 1
Where VFB is the feedback reference voltage (0.92V typ.).
External Bootstrap Diode
Connect a 10nF low ESR ceramic capacitor between the BOOT pin and SW pin. This capacitor provides the gate driver voltage
for the high side MOSFET.
It is recommended to add an external bootstrap diode between an external 5V and the BOOT pin for efficiency improvement
when input voltage is lower than 5.5V or duty ratio is higher than 65%. The bootstrap diode can be a low cost one such as
1N4148 or BAT54.
Soft‐Start
The RS6515 contains an external soft‐start clamp that gradually raises the output voltage. The soft‐start timing can be
programmed by the external capacitor between SS pin and GND. The chip provides a 7μA charge current for the external
capacitor. If a 0.1μF capacitor is used to set the soft‐start and its period will be 13ms(typ.).
Inductor Selection
The inductor value and operating frequency determine the ripple current according to a specific input and output voltage.
The ripple current ΔIL increases with higher VIN and decreases with higher inductance.
VOUT
VOUT
VIN
IL
1
f L
Having a lower ripple current reduces not only the ESR losses in the output capacitors but also the output voltage ripple. High
frequency with small ripple current can achieve highest efficiency operation. However, it requires a large inductor to achieve
this goal.
For the ripple current selection, the value of ΔIL = 0.2375(IMAX) will be a reasonable starting point. The largest ripple current
occurs at the highest VIN. To guarantee that the ripple current stays below the specified maximum, the inductor value should
be chosen according to the following equation：
VOUT
f IL(MAX )
VOUT
L
1
VIN (MAX )
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Inductor Core Selection
The inductor type must be selected once the value for L is known. Generally speaking, high efficiency converters can not
afford the core loss found in low cost powdered iron cores. So, the more expensive ferrite or mollypermalloy cores will be a
better choice.
The selected inductance rather than the core size for a fixed inductor value is the key for actual core loss. As the inductance
increases, core losses decrease. Unfortunately, increase of the inductance requires more turns of wire and therefore the
copper losses will increase.
Ferrite designs are preferred at high switching frequency due to the characteristics of very low core losses. So, design goals
can focus on the reduction of copper loss and the saturation prevention.
Ferrite core material saturates “hard”, which means that inductance collapses abruptly when the peak design current is
exceeded. The previous situation results in an abrupt increase in inductor ripple current and consequent output voltage
ripple.
Do not allow the core to saturate! Different core materials and shapes will change the size/ current and price/current
relationship of an inductor.
Toroid or shielded pot cores in ferrite or permalloy materials are small and do not radiate energy. However, they are usually
more expensive than the similar powdered iron inductors. The rule for inductor choice mainly depends on the price vs. size
requirement and any radiated field/EMI requirements.
CIN and COUT Selection
The input capacitance, CIN, is needed to filter the trapezoidal current at the source of the high side MOSFET. To prevent large
ripple current, a low ESR input capacitor sized for the maximum RMS current should be used. The RMS current is given by：
VOUT
VIN
VIN
VOUT
IRMS IOUT (MAX )
1
This formula has a maximum at VIN = 2VOUT, where IRMS = IOUT/2. This simple worst‐case condition is commonly used for design
because even significant deviations do not offer much relief.
Choose a capacitor rated at a higher temperature than required. Several capacitors may also be paralleled to meet size or
height requirements in the design.
For the input capacitor, a 10μF x 2 Low ESR ceramic capacitor is recommended. For the recommended capacitor, please refer
to table 3 for more detail. The selection of COUT is determined by the required ESR to minimize voltage ripple.
Moreover, the amount of bulk capacitance is also a key for COUT selection 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：
1
VOUT IL ESR
8 fCOUT
The output ripple will be highest at the 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 requirement. Dry tantalum, special polymer,
aluminum electrolytic and ceramic capacitors are all available in surface mount packages. Special polymer capacitors offer
very low ESR value. However, it provides lower capacitance density than other types. Although Tantalum capacitors have the
highest capacitance density, it is important to only use types that pass the surge test for use in switching power supplies.
Aluminum electrolytic capacitors have significantly higher ESR. However, it can be used in cost‐sensitive applications for
ripple current rating and long term reliability considerations. 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.
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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 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 Rectifier Diode
The output rectifier diode supplies the current to the inductor when the high‐side switch is off. To reduce losses due to the
diode forward voltage and recovery times, use a Schottky diode.
Choose a diode whose maximum reverse voltage rating is greater than the maximum input voltage, and whose current rating
is greater than the maximum load current.
Choose a rectifier who’s maximum reverse voltage rating is greater than the maximum input voltage, and who’s current
rating is greater than the maximum load current.
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)
also begins to charge or discharge COUT generating a feedback error signal for 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.
Table 1. Suggested Inductors for Typical Application Circuit
Component Supplier
MAGLAYERS
SUMIDA
Series
MSCDRI‐124‐150M
CDRH104R
Dimensions (mm)
12 x 12 x 5.0
10.1 x 10 x 3.0
10 x 10 x 4.3
TOKO
D104C
Table 2. Suggested Capacitors for CIN and COUT
Component Supplier
Part No.
Capacitance (uF)
Case Size
1206
1206
1210
1210
MURATA
TDK
MURATA
TDK
GRM31CR61E106K
C3225X5R1E106K
GRM32ER71C226M
C3225X5R1C226M
10
10
22
22
Table 3. Schottky Rectifier Selection Guide
2A Load Current
VIN (Max.)
Part No.
Vendor
B320
SK33
SS32
Diodes, Inc. (www.diodes.com)
Pan Jit International (www.panjit.com.tw)
General Semiconductor (www.gensemi.com)
Diodes, Inc. (www.diodes.com)
20V
26V
B330
B340L
SK33
MBRD330
Diodes, Inc. (www.diodes.com)
Diodes, Inc. (www.diodes.com)
On Semiconductor (www.onsemi.com)
Fairchild Semiconductor (www.fairchildsemi.com)
General Semiconductor (www.gensemi.com)
SS33
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MSOP‐10(EP) Dimension
NOTES:
A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
C. Body dimensions do not include mold flash, protrusion.
D. This package is designed to be soldered to a thermal pad on the board.
E. Falls within JEDEC MO‐187 variation BA‐T.
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SOP‐8 Dimension
NOTES:
F. All linear dimensions are in millimeters (inches).
G. This drawing is subject to change without notice.
H. Body length does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not
exceed 0.006 (0.15) per end.
I. Body width does not include interlead flash. Interlead flash shall not exceed 0.017 (0.43) per side.
J. Falls within JEDEC MS‐012 variation AA.
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Soldering Methods for Orister’s Products
1. Storage environment: Temperature=10oC~35oC Humidity=65%±15%
2. Reflow soldering of surface‐mount devices
Figure 1: Temperature profile
t
P
Critical Zone
to T
TP
T
L
P
Ramp-up
TL
t
L
Tsmax
Tsmin
t
S
Preheat
Ramp-down
25
t 25oC to Peak
Time
Profile Feature
Average ramp‐up rate (TL to TP)
Preheat
Sn‐Pb Eutectic Assembly
Pb‐Free Assembly
<3oC/sec
<3oC/sec
‐ Temperature Min (Tsmin
)
100oC
150oC
150oC
200oC
‐ Temperature Max (Tsmax
‐ Time (min to max) (ts)
Tsmax to TL
)
60~120 sec
60~180 sec
‐ Ramp‐up Rate
<3oC/sec
<3oC/sec
Time maintained above:
‐ Temperature (TL)
‐ Time (tL)
183oC
217oC
60~150 sec
240oC +0/‐5oC
60~150 sec
260oC +0/‐5oC
Peak Temperature (TP)
Time within 5oC of actual Peak
10~30 sec
20~40 sec
Temperature (tP)
Ramp‐down Rate
Time 25oC to Peak Temperature
<6oC/sec
<6oC/sec
<6 minutes
<8 minutes
3. Flow (wave) soldering (solder dipping)
Products
Pb devices.
Peak temperature
245oC 5oC
260oC +0/‐5oC
Dipping time
5sec 1sec
5sec 1sec
Pb‐Free devices.
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Important Notice:
© Orister Corporation
Orister cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an Orister product.
No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied.
Orister reserves the right to make changes to their products or specifications or to discontinue any product or service
without notice. Except as provided in Orister’s terms and conditions of sale, Orister assumes no liability whatsoever, and
Orister disclaims any express or implied warranty relating to the sale and/or use of Orister products including liability or
warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other
intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and
operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other
quality control techniques are utilized to the extent Orister deems necessary to support this warranty. Specific testing of
all parameters of each device is not necessarily performed.
Orister and the Orister logo are trademarks of Orister Corporation. All other brand and product names appearing in this
document are registered trademarks or trademarks of their respective holders.
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