FR9886C [FITIPOWER]
21V, 2A/2.5A, 340KHz Synchronous Step-Down DC/DC Converter;
| 型号： | FR9886C |
| 厂家： | 
Fitipower |
| 描述： | 21V, 2A/2.5A, 340KHz Synchronous Step-Down DC/DC Converter |
| 文件： | 总14页 (文件大小：949K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
fitipower integrated technology lnc.
FR9886C
21V, 2A/2.5A, 340KHz Synchronous Step-Down
DC/DC Converter
Description
Features
The FR9886C is a synchronous step-down DC/DC
converter that provides wide 4.5V to 21V input
voltage range. There are two packages (SOP-8 &
SOP-8(EP)) to support 2A/2.5A continuous output
current.
● High Efficiency Synchronous Buck Converter with
Low ISD (<1μA)
● Low Rds(on) Integrated Power MOSFET
● Wide Input Voltage Range: 4.5V to 21V
● Adjustable Output Voltage from 0.925V to 17.85V
● 2A Output Current (Package: SOP-8)
● 2.5A Output Current (Package: SOP-8(EP))
● Fixed 340KHz Switching Frequency
● Current Mode Operation
● Adjustable Soft-Start
● Cycle-by-Cycle Current Limit
● Input Under Voltage Lockout
The
FR9886C
fault
protection
includes
cycle-by-cycle current limit, input UVLO, output over
voltage protection and thermal shutdown. Besides,
adjustable soft-start function prevents inrush current
at turn-on. This device uses current mode control
scheme which provides fast transient response.
In shutdown mode, the supply current is less than
1μA.
● Over-Temperature Protection with Auto Recovery
● SOP-8 and SOP-8 Exposed Pad Packages
The FR9886C is available in SOP-8 and SOP-8
exposed pad packages. It is RoHS compliant and
100% lead (Pb) free.
Applications
● Set-Top-Box
● DVD,LCD Display
● OLPC, Netbook
● Distributed Power System
● Datacom, XDSL
Pin Assignments
Ordering Information
FR9886C□□□
SO Package (SOP-8)
TR: Tape / Reel
8
7
6
5
SS
BST
VIN
LX
1
2
3
4
C: Green
SHDN
COMP
Package Type
SO: SOP-8
SP: SOP-8 (Exposed Pad)
FB
GND
SP Package (SOP-8 Exposed Pad)
1
2
3
4
SS
BST
VIN
LX
8
7
SHDN
COMP
FB
6
5
GND
Figure 1. Pin Assignment of FR9886C
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FR9886C
Typical Application Circuit
C4
0.1μF
R3
100kΩ
7
1
L1
4.7μH
SHDN
BST
LX
2
6
3
5
VIN
VOUT
1.2V
VIN
4.5V to 21V
C1
FR9886C
C6
(optional)
C2
R1
3kΩ
10μF/25V
22μF/6.3V
CERAMIC x 2
CERAMIC x 2
FB
COMP
C5
10nF
SS
8
GND
4
C7
(optional)
R2
10kΩ
R4
5.6KΩ
C3
0.1μF
Figure 2. CIN /COUT use Ceramic Capacitors Application Circuit
C4
0.1μF
R3
100kΩ
7
1
L1
4.7μH
SHDN
BST
2
6
3
5
VOUT
1.2V
VIN
LX
VIN
4.5V to 21V
FR9886C
C6
(optional)
C2
C8
0.1μF/25V
CERAMIC x 1
R1
3kΩ
C1
100μF/25V
EC x 1
100μF/6.3V
EC x 1
COMP
FB
SS
C5
10nF
GND
4
C7
R2
10kΩ
8
R4
5.6KΩ
(optional)
C3
0.1μF
Figure 3. CIN /COUT use Electrolytic Capacitors Application Circuit
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FR9886C
Functional Pin Description
Pin Name
Pin No.
I/O
Pin Function
Voltage Feedback Input Pin. Connect FB and VOUT with a resistive voltage divider. This IC
senses feedback voltage via FB and regulates it at 0.925V.
FB
5
2
7
4
3
8
1
6
I
VIN
I
Power Supply Input Pin. Drive this pin by 4.5V to 21V voltage to power on the chip.
Enable Input Pin. This pin provides a digital control to turn the converter on or off. Connect VIN
with a 100KΩ resistor for self-startup.
I
ꢀꢁꢂ
GND
I
Ground Pin. Connect this pin to exposed pad.
Power Switching Output. It is the output pin of internal high side NMOS which is the switch to
supply power.
LX
SS
O
O
O
O
Soft-Start Pin. This pin controls the soft-start period. Connect a capacitor from SS to GND to
set the soft start period.
High Side Gate Drive Boost Pin. A capacitor rating between 10nF to 0.1μF must be connected
from this pin to LX. It can boost the gate drive to fully turn on the internal high side NMOS.
BST
COMP
Compensation Pin. This pin is used to compensate the regulation control loop. Connect a
series RC network from COMP pin to GND.
Block Diagram
VIN
ISEN
Internal
Regulator
OTP
OVP
VCC
UVLO
&
POR
VCC
SHDN
1M
Oscillator
BST
High-Side
MOSFET
6µA
FB
S
R
Driver
Logic
PWM
Control
Current
Comp
LX
OTP
OVP
SS
UVLO
Low-Side
MOSFET
0.925V
Current
Limit
COMP
GND
Figure 4. Block Diagram of FR9886C
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FR9886C
Absolute Maximum Ratings (Note1)
● Supply Voltage VIN ------------------------------------------------------------------------------------------- -0.3V to +23V
● Enable Voltage ꢀꢁꢂꢃꢄ -------------------------------------------------------------------------------------
-0.3V to +23V
● LX Voltage VLX ------------------------------------------------------------------------------------------------ -1V to VIN+0.3V
● BST Voltage VBST -------------------------------------------------------------------------------------------- VLX-0.3V to VLX+6V
● All Other Pins Voltage -------------------------------------------------------------------------------------- -0.3V to +6V
● Maximum Junction Temperature (TJ) ------------------------------------------------------------------- +150°C
● Storage Temperature (TS) --------------------------------------------------------------------------------- -65°C to +150°C
● Lead Temperature (Soldering, 10sec.) ----------------------------------------------------------------- +260°C
● Power Dissipation @TA=25°C, (PD) (Note2)
SOP-8 ----------------------------------------------------------------------------------------------- 1.39W
SOP-8 (Exposed Pad) -------------------------------------------------------------------------- 2.08W
● Package Thermal Resistance, (θJA)
SOP-8 ----------------------------------------------------------------------------------------------- 90°C/W
SOP-8 (Exposed Pad) -------------------------------------------------------------------------- 60°C/W
● Package Thermal Resistance, (θJC)
SOP-8 ----------------------------------------------------------------------------------------------- 39°C/W
SOP-8 (Exposed Pad) -------------------------------------------------------------------------- 15°C/W
Note 1：Stresses beyond this listed under “Absolute Maximum Ratings" may cause permanent damage to the device.
Note 2：PCB heat sink copper area = 10mm2.
Recommended Operating Conditions
● Supply Voltage VIN ------------------------------------------------------------------------------------------- +4.5V to +21V
● Enable Voltage ꢀꢁꢂꢃꢄ -------------------------------------------------------------------------------------
0V to VIN
● Operation Temperature Range --------------------------------------------------------------------------- -40°C to +85°C
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FR9886C
Electrical Characteristics
(VIN=12V, TA=25°C, unless otherwise specified.)
Parameter
VIN Input Supply Voltage
VIN Quiescent Current
Symbol
Conditions
Min
Typ
Max
Unit
V
VIN
IDDQ
ISD
4.5
21
ꢀꢁꢂꢃꢄ=1.8V, VFB=1.0V
ꢀꢁꢂꢃꢄ=0V
2
mA
μA
V
VIN Shutdown Supply Current
Feedback Voltage
1
VFB
VOVP
4.5V≦VIN≦21V
0.9
0.925
1.5
0.95
Feedback OVP Threshold Voltage
V
SOP-8
130
120
110
High-Side MOSFET RDS(ON) (Note3)
RDS(ON)
mΩ
SOP-8 (EP)
Low-Side MOSFET RDS(ON) (Note3)
High-Side MOSFET Leakage Current
RDS(ON)
ILX(leak)
mΩ
μA
ꢀꢁꢂꢃꢄ=0V, VLX=0V
10
SOP-8
SOP-8 (EP)
2.8
3.1
4
High-Side MOSFET Current Limit
(Note3)
Minimum
Duty
ILIMIT(HS)
A
4.5
1.5
Low-Side MOSFET Current Limit
(Note3)
ILIMIT(LS)
From Drain to Source
A
Current sense to COMP
Transconductance (Note3)
Error Amplifier Transconductance
(Note3)
3.5
A/V
Δ ICOMP = ±10μA
1600
400
340
110
90
μA/V
V/V
KHz
KHz
%
Error Amplifier Voltage Gain (Note3)
Oscillation frequency
FOSC
290
420
Short Circuit Oscillation Frequency
Maximum Duty Cycle
FOSC(short) VFB=0V
DMAX
TMIN
VFB=0.8V
Minimum On Time (Note3)
Input UVLO Threshold
100
4.3
400
6
ns
VUVLO(Vth) VIN Rising
VUVLO(HYS)
ISS
TSS
V
Under Voltage Lockout Threshold
Hysteresis
mV
μA
Soft-Start Current
Soft-Start Period
VSS=0V
CSS=0.1μF
15
ms
ꢀꢁꢂꢃꢄ(L)
0.4
V
ꢁꢂꢃꢄ Input Low Voltage
ꢀꢁꢂꢃꢄ(ꢂ)
ꢅꢁꢂꢃꢄ
TSD
2
V
ꢁꢂꢃꢄ Input High Voltage
ꢁꢂꢃꢄ Input Current
ꢀꢁꢂꢃꢄ=2V
2
μA
°C
Thermal Shutdown Threshold (Note3)
Note 3：Not production tested.
170
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FR9886C
Typical Performance Curves
VIN=12V, VOUT=3.3V, C1=10μF x 2, C2=22μF x 2, L1=10μH, TA=+25°C, unless otherwise noted.
100
100
95
90
95
90
85
80
85
80
75
70
65
60
55
50
75
70
65
60
55
50
VOUT = 1.2V
VOUT = 1.2V
VIN= 5V
VIN= 12V
VIN= 5V
VIN= 12V
0.1
0.4
0.7
1
1.3
1.6
1.9
2.2
0.1
0.4
0.7
1
1.3
1.6
1.9
2.2
2.5
Load Current (A)
Load Current (A)
Figure 5. Efficiency vs. Loading (SOP-8)
Figure 6. Efficiency vs. Loading (SOP-8 Exposed Pad)
100
95
90
85
80
75
70
65
60
55
50
100
95
90
85
80
75
70
65
VIN= 5V
VIN= 12V
VIN= 23V
VOUT = 3.3V
VIN= 5V
VIN= 12V
VIN= 23V
60
55
50
VOUT = 3.3V
0.1
0.4
0.7
1
1.3
1.6
1.9
2.2
2.5
0.1
0.4
0.7
1
1.3
1.6
1.9
2.2
Load Current (A)
Load Current (A)
Figure 7. Efficiency vs. Loading (SOP-8)
Figure 8. Efficiency vs. Loading (SOP-8 Exposed Pad)
100
100
95
90
85
80
75
70
65
60
95
90
85
80
75
70
65
60
55
50
VOUT = 5V
VIN= 12V
VIN= 23V
VOUT = 5V
VIN= 12V
VIN= 23V
55
50
0.1
0.4
0.7
1
1.3
1.6
1.9
2.2
0.1
0.4
0.7
1
1.3
1.6
1.9
2.2
2.5
Load Current (A)
Load Current (A)
Figure 9. Efficiency vs. Loading (SOP-8)
Figure 10. Efficiency vs. Loading (SOP-8 Exposed Pad)
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Typical Performance Curves (Continued)
VIN=12V, VOUT=3.3V, C1=10μF x 2, C2=22μF x 2, L1=10μH, TA=+25°C, unless otherwise noted.
0.950
0.945
380
370
0.940
0.935
0.930
0.925
0.920
0.915
0.910
0.905
0.900
360
350
340
330
320
310
300
290
280
-40
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
100
Temperature ( Degrees C )
Temperature ( Degrees C )
Figure 11. Feedback Voltage vs. Temperature
IOUT=0A
Figure 12. Frequency vs. Temperature
IOUT=2.5A
VIN 200mV/div. (AC)
VIN 10mV/div. (AC)
VOUT 20mV/div. (AC)
VOUT 20mV/div. (AC)
IL
1A/div.
5V/div.
IL
1A/div.
5V/div.
VLX
VLX
4μs/div.
Figure 13. DC Ripple Waveform
4μs/div.
Figure 14. DC Ripple Waveform
IOUT=2.5A
5V/div.
IOUT=0A
ꢃ
5V/div.
ꢃ
ꢀꢁꢂ
ꢀꢁꢂ
VOUT 0.5V/div.
VOUT 1V/div.
IL
1A/div.
IL
1A/div.
5V/div.
VLX
VLX
5V/div.
4ms/div.
Figure 15. Startup Through ꢁꢂꢃꢄ Waveform
FR9886C-0.4-JUL-2012
4ms/div.
Figure 16. Startup Through ꢁꢂꢃꢄ Waveform
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FR9886C
Typical Performance Curves (Continued)
VIN=12V, VOUT=3.3V, C1=10μF x 2, C2=22μF x 2, L1=10μH, TA=+25°C, unless otherwise noted.
IOUT=0A
IOUT=2.5A
ꢃ
5V/div.
ꢀꢁꢂ
ꢃ
5V/div.
ꢀꢁꢂ
VOUT 1V/div.
VOUT 0.5V/div.
IL
1A/div.
5V/div.
IL
1A/div.
5V/div.
VLX
VLX
200μs/div.
4ms/div.
Figure 17. Shutdown Through ꢁꢂꢃꢄ Waveform
IOUT=100mA to 2.5A Step
Figure 18. Shutdown Through ꢁꢂꢃꢄ Waveform
VOUT 500mV/div.
VOUT ,, 1V/div.
IL
1A/div.
IL
2A/div.
40μs/div.
400μs/div.
Figure 19. Load Transient Waveform
Figure 20. Short Circuit Test
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Function Description
The FR9886C is a high efficiency and constant
frequency current mode step-down synchronous
Input Under Voltage Lockout
When the FR9886C is power on, the internal
circuits will be held inactive until VIN voltage
exceeds the input UVLO threshold voltage. And
the regulator will be disabled when VIN is below the
input UVLO threshold voltage. The hysteretic of
the UVLO comparator is 250mV (typ).
DC/DC converter.
(130mΩ, typ) and low-side (110mΩ, typ) power
switches. There are two packages (SOP-8 &
It has integrated high-side
SOP-8(EP)) to support 2A/2.5A continuous output
current. It regulates input voltage from 4.5V to 21V
and down to an output voltage as low as 0.925V.
Short Circuit Protection
Control Loop
The FR9886C provides short circuit protection
function to prevent the device damage from short
condition. When the short condition occurs and
the feedback voltage drops lower than 0.4V, the
oscillator frequency will be reduced to 110KHz to
prevent the inductor current increasing beyond the
current limit. In the meantime, the current limit will
also be reduced to lower the short current. Once
the short condition is removed, the frequency and
current limit will return to normal.
During normal operation, the output voltage is
sensed at FB pin by a resistive voltage divider and
amplified through the error amplifier. The voltage of
error amplifier output pin -- COMP is compared to
the switch current to control the RS latch. At each
cycle, the high side NMOS will be turned on when
the oscillator sets the RS latch and turned off when
current comparator resets the RS latch. When the
load current increases, the FB pin voltage will drop
below 0.925V, and it will cause the COMP voltage
increasing until average inductor current arrives at
new load current.
Over Current Protection
The FR9886C over current protection function is
implemented by using cycle-by-cycle current limit
architecture. The inductor current is monitored by
measuring the high-side MOSFET series sense
resistor voltage. When the load current increases,
the inductor current will also increase. When the
peak inductor current reaches the current limit
threshold, the output voltage will start to drop.
When the over current condition is removed, the
output voltage will return to the regulated value.
Enable
The FR9886C ꢁꢂꢃꢄ pin provides digital control to
turn on/turn off the regulator. When the voltage of
ꢁꢂꢃꢄ exceeds the threshold voltage, the regulator
will start the soft start function. If the ꢁꢂꢃꢄ pin
voltage is below the shutdown threshold voltage, the
regulator will turn into shutdown mode and shutdown
current will be smaller than 1μA. For auto start-up
operation, connect ꢁꢂꢃꢄ to ꢀꢅꢄ through a 100KΩ
resistor.
Over Temperature Protection
The FR9886C incorporates an over temperature
protection circuit to protect itself from overheating.
When the junction temperature exceeds the thermal
shutdown threshold temperature, the regulator will
be shutdown. And the hysteretic of the over
temperature protection is 60°C (typ).
Soft Start
The FR9886C employs adjustable soft start function
to reduce input inrush current during start up. When
the device turns on, a 6μA current will begin to
charge the capacitor which is connected from SS pin
to GND. The equation for the soft start time is
shown as below:
Compensation
The stability of the feedback circuit is controlled by
COMP pin.
application circuit is optimized for particular
requirements. If different conversions are
The compensation value of the
ꢀ
Cꢁꢁ nF ꢆꢀFꢇ
ꢀ
Tꢁꢁ ms =
ꢀ
ꢅꢁꢁ μA
required, some of the components may need to be
changed to ensure stability.
The VFB voltage is 0.925V and the ISS current is 6μA.
ꢅf a 0.1μF capacitor is connected from ꢁꢁ pin to
GND, the soft start time will be 15ms.
Output Over Voltage Protection
When the FB pin voltage exceeds 1.5V, the output
over voltage protection function will be triggered and
turn off the high-side/low-side MOSFET.
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Application Information
Output Voltage Setting
A low ESR capacitor is required to keep the noise
minimum.
Ceramic capacitors are better, but
The output voltage VOUT is set by using a resistive
divider from the output to FB. The FB pin regulated
voltage is 0.925V. Thus the output voltage is:
tantalum or low ESR electrolytic capacitors may
also suffice. When using tantalum or electrolytic
capacitors, a 0.1μF ceramic capacitor should be
placed as close to the IC as possible.
R1
ꢀOꢈT=0.ꢉ25ꢀꢆ ꢁ1ꢊ
ꢂ
R2
Output Capacitor Selection
Table 2 lists recommended values of R1 and R2 for
most used output voltage.
The output capacitor is used to keep the DC output
voltage and supply the load transient current.
When operating in constant current mode, the
output ripple is determined by four components:
Table 2 Recommended Resistance Values
VOUT
5V
R1
R2
44.2kΩ
26.1kΩ
16.ꢉkΩ
ꢉ.53kΩ
3kΩ
10kΩ
10kΩ
10kΩ
10kΩ
10kΩ
ꢀ
ꢀ
ꢀRꢅPPLꢌ t =ꢀRꢅPPLꢌ(C) t ꢊꢀRꢅPPLꢌ(ꢌꢁR)(t)
3.3V
2.5V
1.8V
1.2V
ꢊꢀRꢅPPLꢌ(ꢌꢁL)(t)ꢊꢀꢄOꢅꢁꢌ(t)
The following figures show the form of the ripple
contributions.
VRIPPLE(ESR)(t)
Place resistors R1 and R2 close to FB pin to prevent
stray pickup.
Input Capacitor Selection
(t)
The use of the input capacitor is filtering the input
voltage ripple and the MOSFETS switching spike
voltage. Because the input current to the step-down
converter is discontinuous, the input capacitor is
required to supply the current to the converter to
keep the DC input voltage. The capacitor voltage
rating should be 1.25 to 1.5 times greater than the
maximum input voltage. The input capacitor ripple
current RMS value is calculated as:
+
VRIPPLE(ESL) (t)
(t)
(t)
+
VRIPPLE(C) (t)
ꢀ
ꢅꢅꢄ(RMꢁ)=ꢅOꢈTꢆꢃꢃꢆ 1ꢋꢃ
ꢀOꢈT
ꢃ=
ꢀꢅꢄ
+
VNOISE (t)
Where D is the duty cycle of the power MOSFET.
This function reaches the maximum value at D=0.5
and the equivalent RMS current is equal to IOUT/2.
The following diagram is the graphical representation
of above equation.
=
VRIPPLE(t)
2.5A
2A
1.5A
1A
(t)
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Application Information (Continued)
ꢀOꢈT
ꢀ
That will lower ripple current and result in lower
ꢀRꢅPPLꢌ(ꢌꢁR, pꢋp)
=
ꢆ ꢁ1ꢋ OꢈTꢂ ꢆꢌꢁR
output ripple voltage.
The ΔꢅL is inductor
FOꢁCꢆL
ꢀꢅꢄ
peak-to-peak ripple current:
ꢌꢁL
ꢀRꢅPPLꢌ(ꢌꢁL, pꢋp)
=
ꢆꢀꢅꢄ
ꢀOꢈT
ꢀ
ꢎꢅ=
ꢆ ꢁ1ꢋ OꢈTꢂ
LꢊꢌꢁL
ꢀOꢈT
ꢍꢆFOꢁC2ꢆLꢆCOꢈT
FOꢁCꢆL
ꢀꢅꢄ
ꢀ
ꢆꢁ1ꢋ OꢈTꢂ
ꢀꢅꢄ
ꢀRꢅPPLꢌ(C, pꢋp)
=
The following diagram is an example to graphical
represent ΔꢅL equation.
Where FOSC is the switching frequency, L is the
inductance value, VIN is the input voltage, ESR is the
equivalent series resistance value of the output
capacitor, ESL is the equivalent series inductance
value of the output capacitor and the COUT is the
output capacitor.
L=4.7μꢀ
L=6.8μꢀ
L=10μꢀ
Low ESR capacitors are preferred to use. Ceramic,
tantalum or low ESR electrolytic capacitors can be
used depending on the output ripple requirements.
When using the ceramic capacitors, the ESL
component is usually negligible.
It is important to use the proper method to eliminate
high frequency noise when measuring the output
ripple. The figure shows how to locate the probe
across the capacitor when measuring output ripple.
Removing the scope probe plastic jacket in order to
expose the ground at the tip of the probe. It gives a
very short connection from the probe ground to the
capacitor and eliminates noise.
VOUT=3.3V, FOSC=340KHz
A good compromise value between size and
efficiency is to set the peak-to-peak inductor ripple
current ΔꢅL equal to 30% of the maximum load
current. But setting the peak-to-peak inductor
ripple current ΔꢅL between 20%~50% of the
maximum load current is also acceptable. Then
the inductance can be calculated with the following
equation:
Probe Ground
ꢎꢅ=0.3ꢆꢅOꢈT(MAꢏ)
ꢀ
ꢀꢅꢄꢋꢀOꢈT ꢆꢀOꢈT
L=
ꢀꢅꢄꢆFOꢁCꢆꢎꢅL
To guarantee sufficient output current, peak
inductor current must be lower than the FR9886C
high-side MOSFET current limit.
inductor current is as below:
The peak
VOUT
GND
ꢎꢅL
Ceramic Capacitor
Inductor Selection
ꢅPꢌAK=ꢅOꢈT(MAꢏ)
ꢊ
2
The output inductor is used for storing energy and
filtering output ripple current. But the trade-off
condition often happens between maximum energy
storage and the physical size of the inductor. The
first consideration for selecting the output inductor is
to make sure that the inductance is large enough to
keep the converter in the continuous current mode.
FR9886C-0.4-JUL-2012
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fitipower integrated technology lnc.
FR9886C
Application Information (Continued)
Compensation Components Selection
4. The exposed pad of the package should be
soldered to an equivalent area of metal on the
PCB. This area should connect to the GND
plane and have multiple via connections to the
back of the PCB as well as connections to
intermediate PCB layers. The GND plane area
connecting to the exposed pad should be
maximized to improve thermal performance.
COMP
C5
FR9886C
C7
(optional)
R4
5. Multi-layer PCB design is recommended.
Select the appropriate compensation value by
following procedure:
1. Calculate the R4 value with the following equation:
R1
R3
2 ꢆCOꢈTꢆ0.1ꢆFOꢁCꢆꢀOꢈT
R4<
R2
ꢐꢌAꢆꢐCꢁꢆꢀRꢌF
8
1
7
6
5
where GEA is the error amplifier voltage gain, and
GCS is the current sense gain.
GND
2. Calculate the C5 value with the following equation:
C2
C1
4
2
3
4
C5ꢑ
VIN
2 ꢆR4ꢆ0.1ꢆFOꢁC
VOUT
LX
L1
C4
External Diode Selection
Figure 21. FR9886C Recommended Layout Diagram
For 5V input applications, it is recommended to add
an external boost diode. This helps improving the
efficiency. The boost diode can be a low cost one,
such as 1N4148.
R1
R3
D1
R2
1N4148
8
1
7
6
5
VIN
BST
VIN
5V
Exposed
GND
FR9886C
C4
Pad
LX
C2
C1
4
2
3
VIN
VOUT
LX
L1
C4
PCB Layout Recommendation
The device’s performance and stability are
dramatically affected by PCB layout. It is
Figure 22. FR9886C Recommended Layout Diagram
recommended to follow these general guidelines
shown as below:
1. Place the input capacitors and output capacitors
as close to the device as possible. The traces
which connect to these capacitors should be as
short and wide as possible to minimize parasitic
inductance and resistance.
2. Place feedback resistors close to the FB pin.
3. Keep the sensitive signal (FB) away from the
switching signal (LX).
FR9886C-0.4-JUL-2012
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fitipower integrated technology lnc.
FR9886C
Outline Information
SOP-8 Package (Unit: mm)
DIMENSION IN MILLIMETER
SYMBOLS
UNIT
MIN
1.35
0.10
1.25
0.31
4.80
3.80
1.20
5.80
0.40
MAX
1.75
0.25
1.50
0.51
5.00
4.00
1.34
6.20
1.27
A
A1
A2
B
D
E
e
H
L
Note：Followed from JEDEC MO-012-E
Carrier Dimensions
FR9886C-0.4-JUL-2012
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fitipower integrated technology lnc.
FR9886C
Outline Information (Continued)
SOP-8 (Exposed Pad) Package (Unit: mm)
DIMENSION IN MILLIMETER
SYMBOLS
UNIT
MIN
1.25
0.00
1.25
0.31
4.80
3.04
3.80
2.15
1.20
5.80
0.40
MAX
1.70
0.15
1.55
0.51
5.00
3.50
4.00
2.41
1.34
6.20
1.27
A
A1
A2
B
D
D1
E
E1
e
H
L
Note：Followed From JEDEC MO-012-E.
Carrier Dimensions
Life Support Policy
Fitipower’s products are not authorized for use as critical components in life support devices or other medical systems.
FR9886C-0.4-JUL-2012
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