3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
Package
General Descriptions
The NR885E is synchronous buck regulator ICs
integrates High-side and Low-side power MOSFETs.
With the current mode control, ultra low ESR capacitors
such as ceramic capacitors can be used. The ICs have
protection functions such as Over-Current Protection
(OCP), Under-Voltage Lockout (UVLO) and Thermal
Shutdown (TSD). An adjustable Soft-Start by an external
capacitor prevents the excessive inrush current at turn-on
the regulator. The ICs integrate phase compensation
circuit which reduces the number of external components
and simplifies the design of customer application. The
ON/OFF pin (EN Pin) turns the regulator on or off and
helps to achieve low power consumption requirements.
The NR885E is available in an 8-pin SOIC package with
an exposed thermal pad on the back side.
Features & Benefits
Exposed SOIC 8
Thermally enhanced 8-Pin package
Electrical Characteristics
Current mode PWM control
Up to 95% efficiency
Stable with low ESR ceramic output capacitors
Built-in protection function
Over Current Protection (OCP)
Thermal Shutdown (TSD)
Under Voltage Lockout (UVLO)
Built-in phase compensation
Adjustable Soft-Start with an external capacitor
Turn ON/OFF the regulator function
3A output current
Operating input range VIN = 4.5V～18V
Output adjustable VO= 0.8V～14V
Fixed 350kHz frequency
Applications
LCD TV / Blu-Ray / Set top box
Green Electronic products
Other power supply
Basic Connection of NR885E
NR885E
C1, C2: 10μF / 25V
C4, C5: 22μF / 16V
C9: 0.1μF
C3: 0.1μF
Rev.1.1
R1: 100kΩ
L1: 10μH
R3: 22Ω
R4: 8.2 kΩ, R5: 4.3kΩ (Vo=3.3V)
R6: 3.9kΩ
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
Series Lineup
(1)
(2)
Product No.
fSW
VIN
NR885E
350kHz
VO
(1)
4.5V to 18V
0.8V to 14V
IO
(2)
3A
The minimum input voltage shall be either of 4.5V or V O+3V, whichever is higher.
The I/O condition limited by the Minimum on-time (TON(MIN)).
Absolute Maximum Ratings
Parameter
DC input voltage
Symbol
Ratings
Units
VIN
20
V
Power dissipation
(3)
PD
1.76
W
Junction temperature
(4)
TJ
40 to 150
°C
Glass-epoxy board mounting
in a 30×30mm.
(copper area in a 25×25mm)
Max TJ =150°C
Storage temperature
Thermal resistance
(junction- Pin No. 4)
TS
40 to 150
°C
θJP
26
°C /W
Thermal resistance
(junction-ambient air)
θJA
71
°C /W
(3)
(4)
Condition
Glass-epoxy board mounting
in a 30×30mm.
(copper area in a 25×25mm)
Limited by thermal shutdown.
The temperature detection of thermal shutdown is about 160°C
Recommended Operating Conditions
Parameter
DC input voltage
Symbol
(5)
Ratings
Units
MIN
MAX
VIN
Vo+3
18
V
Io
0
3.0
A
Vo
0.8
14
V
Condition
(6)
DC output current
Output voltage
(7)
(7)
Ambient operating temperature
Top
85
°C
40
(5)
The minimum value of input voltage is taken as the larger one of either 4.5V or VO +3V.
In the case of VIN=VO +1～VO +3V , it is set to IO = Max. 2A
(6)
Recommended circuit refers to Typical Application Circuit.
(7)
To be used within the allowable package power dissipation characteristics.
Rev.1.1
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
Electrical Characteristics
Ta = 25°C
Parameter
Symbol
Reference voltage
Output voltage temperature
coefficient
Switching frequency
Ratings
MIN
TYP
MAX
VREF
0.784
0.800
0.816
⊿VREF/⊿T
―
±0.05
―
350
420
fSW
280
Units
Test conditions
V
VIN = 12V，IO = 1.0A
V = 12V, IO = 1.0A
mV/°C IN
40°C to +85°C
VIN =12V, VO=3.3V,
kHz
IO =1A
VIN = 6.3V～18V,
mV
VO = 3.3V, IO = 1A
VIN = 12V, VO = 3.3V,
mV
IO = 0.1A～3.0A
Line regulation
(8)
VLine
―
50
―
Load regulation
(8)
VLoad
―
50
―
Over current protection
threshold
IS
3.1
―
6.0
A
Supply Current
IIN
―
6
―
mA
IIN(off)
0
―
10
μA
IEN/SS
6
10
14
μA
VSS=0V, VIN=12V
VSSH
―
3.0
―
V
VIN =12V
50
100
μA
VEN= 10V
VIN =12V
Shutdown Supply Current
SS Pin
EN Pin
Source current
at low level
voltage
High level
voltage
Sink current
IEN
Threshold voltage
Max on-duty
(8)
VC/EH
0.7
1.4
2.1
V
DMAX
―
90
―
%
TON(MIN)
―
150
―
nsec
151
165
―
°C
―
20
―
°C
VIN = 12V, VO = 3.3V
VIN = 12V
VEN=10kΩ pull up to VIN
VIN =12V, IO =0A,
VEN=0V
(8)
Minimum on-time
(9)
Thermal shutdown threshold
(8)
TSD
temperature
Thermal shutdown
(8)
restart hysteresis
TSD_hys
of temperature
(8)
Guaranteed by design, not tested.
(9)
The I/O characteristic are limited by the TON(MIN).
Rev.1.1
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
Typical Performance Characteristics
NR885E Typical Performance Characteristics
Efficiency
Efficiency [%] EFF(%)
効率(Vo=1.8V)
VO=1.8V
100
90
80
70
60
50
40
30
20
10
0
VIN=5V
6V
8V
10V
12V
15V
18V
0
0.5
1
1.5
2
2.5
3
3.5
Io(A)
Output Current: IO [A]
Efficiency [%] EFF(%)
NR880K ES1 HSOP8
S1 RT(Vo=3.3V)
VO=3.3V
100
90
80
70
60
50
40
30
20
10
0
VIN=6V
8V
10V
12V
15V
18V
0
0.5
1
1.5
2
2.5
3
EfficiencyEfficiency[%]
[%]
3.5
Io(A)
Output Current: IO [A]
VO=5V
Vo=5V
100
90
80
70
60
50
40
30
20
10
0
VIN=8V
10V
12V
15V
18V
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
[%]
EfficiencyEfficiency[%]
Output Current: IO [A] 負荷電流Io[A]
VO=12V
Vo=12V
100
90
80
70
60
50
40
30
20
10
0
VIN =14V
15V
18V
0.0
0.5
1.0
1.5
2.0
Output Current: IO [A]
Rev.1.1
2.5
3.0
3.5
負荷電流Io[A]
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
NR885E Typical Performance Characteristics
Output startup
Over Current Protection
VVo=3.3V
O=3.3V
出力電圧Vo [V]
Output Voltage
[V]
Output Voltage [V]
VO=3.3V, Load = Constant Resistance
Io = 0A
0.5A
1A
2A
3A
3.50
3.00
2.50
VIN = 8V
10V
12V
15V
18V
2.00
1.50
1.00
0.50
0.00
0.0
Input Voltage
0.5
3.29
3.27
3.25
0.5
1
1.5
2
2.5
3
Output Current IO [A]
3.5
4.0
4.5
5.0
出力電流Io [A]
VO=3.3V
400
390
380
370
360
350
340
330
320
310
300
VIN = 6V
8V
10V
12V
15V
18V
0
0.5
1
1.5
2
2.5
3
Output Current IO [A]
Supply Current : IIN
NR880K ES1 DIP28
Iqoff vs VIN at RT
V S1=0V
Io=0A
VO=3.3V
EN:Open
3.5
Io(A)
7
10
9
8
7
6
5
4
3
2
1
0
Current [mA]
無負荷時動作電流Iq [mA ]
A)
Iqoff( μ
Current [μA]
3.0
Shutdown Supply Current : IIN(off)
EN
6
5
4
3
2
1
0
0
2
4
6
8
10
12
14
Input Voltage VIN [V]
Rev.1.1
3.5
Io(A)
ｆ(kHz)
Switching Frequency {kHz}
Output Voltage [V]Vo(V)
VIN = 6V
8V
10V
12V
15V
18V
3.31
2.5
NR880K ES1 HSOP8 S1 RT(Vo=3.3V)
O
3.33
2.0
Switching Frequency: fSW
NR880K ES1 V
HSOP8
S1 RT(Vo=3.3V)
=3.3V
3.35
1.5
Output Current IO [A]
Load Regulation: VLoad
0
1.0
VIN [V]
16
18
20
VIN(V)
0
2
4
6
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10
12
14
16
18
入力電圧Vin [V]
Input Voltage VIN [V]
5
3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
Functional Block Diagram
Pin Assignments & Functions
Pin Assignments
Pin Functions
Pin No.
Symbol
1
BS
2
IN
Rev.1.1
3
SW
4
GND
5
FB
6
NC
7
EN
8
SS
Description
High-side Boost input.
BS supplies the drive for High-side Nch-MOSFET switch.
Connect a capacitor and a resistor between SW to BS.
Power input. IN supplies the power to the IC as well as the regulator switches
Power switching output.
SW supplies power to the output.
Connect the LC filter from SW to the output.
Note that a capacitor is required from SW to BS to supply the power the High-side
switch
Ground
Connect the exposed pad to Pin No.4
Feedback input Pin to compare Reference Voltage. The feedback threshold is 0.8V.
To set the output voltage, FB Pin is required to connect between resistive voltage divider
R4 and R6.
No Connection.
Enable input.
Drive EN Pin high to turn on the regulator, low to turn it off.
Soft-Start control input.
To set the soft-start period, connect to a capacitor between GND.
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
External Components Design Guide
(1)Diode D1
・Flywheel diode D1 can be connected to enhance the efficiency.
・The schottky-barrier diode must be used for D1. If other diodes like fast recovery diodes are used, IC may be
damaged because of the reverse voltage applied by the recovery voltage or ON voltage.
(2)Choke coil L1
・If the winding resistance of the choke coil is too high, the efficiency may go down to the extent that it is out of the rating.
・As the start current of the over current protection is approximately 4A, attention must be paid to the heating of the choke
coil by the magnetic saturation due to overload or short-circulated load.
(3)Capacitor C1( C2), C4(C5), C7
・As large ripple currents across C1 (C2) and C4 (C5), capacitors with high frequency and low impedance for SMPS must
be used. Especially when the impedance of C4 (C5) is high, the switching waveform may not be normal at low
temperature.
・C7 is a capacitor for soft start. A soft-start controls the over-shoot of the output voltage rising and rush current.
(4)Resistor R4, R5, R6
・R4, R5, R6 are resistor to the Output Voltage. IADJ is required to set to 0.2mA.
R4, R5, R6 are calculated by the equation (1).
R 4 R5
VO VFB VO 0.8
I ADJ
0.2 10 3
， R 6
VFB
0.8
≒ 4.0k
I ADJ
0.2 10 3
------- (1)
In order to have optimum operating condition, each component must be connected with the minimum distance.
Rev.1.1
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
Allowable package power dissipation
NOTES
1) Glass-epoxy board mounting in a 30×30mm
2) copper area : 25×25mm
3) The power dissipation is calculated at the junction temperature 125 °C
4) Losses can be calculated by the following equation.
As the efficiency is subject to the input voltage and output current, it shall be obtained from the efficiency curve and
substituted in percent
5) Thermal design for D1 shall be made separately.
100
PD VO I O
1
x
VO: Output voltage
VIN : Input voltage
IO : Output current
ηx : Efficiency (%)
Rev.1.1
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
PCB Layout Example& Recommended Land Pattern
(1) Each ground of all components is connected as close as possible to the Pin No.4 at one point.
(2) To help heat dissipation, connect a large copper plane to exposed pad on the back side of the package.
The copper plane is required for GND
Front Side: Component Side (double sided board)
Back Side: GND Side (double sided board)
Circuit Diagram of Demo-board PCB
NR885E
Circuit-diagram
As for the part number of the demonstration board "circuit-diagram", a circuit board concerned doesn't partly fit each
other with the above application circuit example and so on for NR110, NR120 and the NR880 series common use.
Approve it in advance. C9, R9 and C10 aren't used in the NR880 series. And, D1, D2, R3, R8,R10, C11 and C12 are
options.
Rev.1.1
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
NOTES:
Real size of the PCB is 60mm×60mm
0.61 (0.024)
1.27 (0.050)
1.60 (0.063)
2.35 (0.092)
5.40 (0.213)
3.24 (0.127)
NOTES:
1) Dimension is in millimeters, dimension in bracket is in inches.
2) Drawing is not to scale.
Recommended land pattern
Rev.1.1
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
Package Outline
Exposed SOIC8 package
6.918(0.244)
5.893(0.232)
2.16±0.127
(0.085±0.005)
3.89 (0.153)
3.73 (0.147)
0.508(0.020)
0.330(0.130)
3.18±0.127
(0.120±0.005)
Top view
Bottom view
4.902±0.102
(0.193± 0.004)
1.448±0.05
(0.057±0.002)
1.27(0.050) BSC
0.102(0.004)
0.1524(0.006 )
0.000(0.000)
Front view
Side view
NOTES:
1) Dimension is in millimeters, dimension in bracket is in inches.
2) Drawing is not to scale.
3) Pb-free: Device composition comply with the RoHS directive.
Package Marking
NR885E
SKYMW
XXXX
Part Number
Lot Number
Y= last digit of the year (0-9)
M= Month (1-9, O, N, or D)
W= Week Code (1-3)
Sanken Control Number
Rev.1.1
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
OPERATING PRECAUTIONS
Reliability can be affected adversely by improper storage environments and handling methods. Please observe the
following cautions.
Cautions for Storage
Ensure that storage conditions comply with the standard temperature (5 to 35°C) and the standard relative humidity
(around 40 to 75%); avoid storage locations that experience extreme changes in temperature or humidity.
Avoid locations where dust or harmful gases are present and avoid direct sunlight.
Reinspect for rust on leads and solderability of products that have been stored for a long time.
Cautions for Testing and Handling
When tests are carried out during inspection testing and other standard test periods, protect the products from power
surges from the testing products, shorts between the product pins, and wrong connections. In addition, avoid tests
exceeded ratings
Soldering
When soldering the products, please be sure to minimize the working time, within the following limits.
・Reflow Preheat ; 180°C / 90±30 s
Heat ; 250°C / 10±1s (260°C peak ,2times)
・Soldering iron ; 380±10°C / 3.5±0.5s (1time)
Electrostatic Discharge
When handling the products, the operator must be grounded. Grounded wrist straps worn should have at least 1MΩ of
resistance from the operator to ground to prevent shock hazard, and it should be placed near the operator.
Workbenches where the products are handled should be grounded and be provided with conductive table and floor mats.
When using measuring equipment such as a curve tracer, the equipment should be grounded.
When soldering the products, the head of a soldering irons or the solder bath must be grounded in order to prevent leak
voltages generated by them from being applied to the products.
The products should always be stored and transported in Sanken shipping containers or conductive containers, or be
wrapped in aluminum foil.
Rev.1.1
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3A, 18V, 350kHz , Synchronous Buck Regulator
NR885E
Dec./02/2014
IMPORTANTS NOTES
The contents in this document are subject to changes, for improvement and other purposes, without notice.
Make sure that this is the latest revision of the document before use.
Application and operation examples described in this document are quoted for the sole purpose of reference for
the use of the products herein and Sanken can assume no responsibility for any infringement of industrial
property rights, intellectual property rights or any other rights of Sanken or any third party which may result
from its use.
Although Sanken undertakes to enhance the quality and reliability of its products, the occurrence of failure and
defect of semiconductor products at a certain rate is inevitable. Users of Sanken products are requested to take,
at their own risk, preventative measures including safety design of the equipment or systems against any
possible injury, death, fires or damages to the society due to device failure or malfunction.
Sanken products listed in this document are designed and intended for the use as components in general purpose
electronic equipment or apparatus (home appliances, office equipment, telecommunication equipment,
measuring equipment, etc.).
When considering the use of Sanken products in the applications where higher reliability is required
(transportation equipment and its control systems, traffic signal control systems or equipment, fire/crime alarm
systems, various safety devices, etc.), please contact your nearest Sanken sales representative to discuss, prior to
the use of the products herein.
The use of Sanken products without the written consent of Sanken in the applications where extremely high
reliability is required (aerospace equipment, nuclear power control systems, life support systems, etc.) is strictly
prohibited.
In the case that you use Sanken semiconductor products or design your products by using Sanken
semiconductor products, the reliability largely depends on the degree of derating to be made to the rated values.
Derating may be interpreted as a case that an operation range is set by derating the load from each rated value or
surge voltage or noise is considered for derating in order to assure or improve the reliability. In general, derating
factors include electric stresses such as electric voltage, electric current, electric power etc., environmental
stresses such as ambient temperature, humidity etc. and thermal stress caused due to self-heating of
semiconductor products. For these stresses, instantaneous values, maximum values and minimum values must
be taken into consideration.
In addition, it should be noted that since power devices or IC’s including power devices have large self-heating
value, the degree of derating of junction temperature affects the reliability significantly.
When using the products specified herein by either (i) combining other products or materials therewith or (ii)
physically, chemically or otherwise processing or treating the products, please duly consider all possible risks
that may result from all such uses in advance and proceed therewith at your own responsibility.
Anti radioactive ray design is not considered for the products listed herein.
Sanken assumes no responsibility for any troubles, such as dropping products caused during transportation out
of Sanken’s distribution network.
The contents in this document must not be transcribed or copied without Sanken’s written consent.
Rev.1.1
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