fitipower integrated technology lnc.
FR9801
85T
21V, 2A, 600KHz Synchronous Step-Down
DC/DC Converter
Description
The FR9801 is a synchronous step-down DC/DC
converter that provides wide 4.5V to 21V input
voltage range and 2A continuous load current
capability.
The FR9801 fault protection includes cycle-by-cycle
current limit, UVLO, output overvoltage protection
and thermal shutdown. The adjustable soft-start
function prevents inrush current at turn-on. This
device uses current mode control scheme which
provides
fast
transient
response.
Internal
compensation
function
reduces
external
compensation components and simplifies the design
process. In shutdown mode, the supply current is
less than 1μA.
The FR9801 is available in
SOT-23-6
package and
provides good thermal conductance.
Features
High Efficiency up to 94%
Low R
DS(ON)
Integrated Power MOSFET
Internal Compensation Function
Wide Input Voltage Range: 4.5V to 21V
Adjustable Output Voltage from 0.8V to 17.85V
2A Output Current
Fixed 600KHz Switching Frequency
Current Mode Operation
Cycle-by-Cycle Current Limit
Over-Temperature Protection with Auto Recovery
Output Overvoltage Protection
Under Voltage Lockout
<1μA Shutdown Current
SOT-23-6
Package
Applications
STB (Set-Top-Box)
LCD Display, TV
Distributed Power System
Networking, XDSL Modem
Pin Assignments
S6 Package (SOT-23-6)
LX VIN SHDN
Ordering Information
FR9801
□□□
TR: Tape/Reel
C: Green
Package Type
S6: SOT-23-6
6
1
4
5
(Marking)
2
3
BST GND FB
SOT-23-6 Marking
Fig
ure 1. Pin Assignment of FR9801
Part Number
FR9801S6CTR
Product Code
B1G
FR9801-0.5-JUL-2013
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fitipower integrated technology lnc.
FR9801
85T
Typical Application Circuit
R3
100kΩ
C3
0.1μF
4
SHDN
VIN
4.5V to 21V
C1
10μF/25V
CERAMIC x 2
1
BST
LX 6
L1
4.7μH
VOUT
3.3V
R1
30.9kΩ 1%
C4
(optional)
5
VIN
FR9801
FB
GND
2
3
C2
22μF/6.3V
CERAMIC x 2
R2
9.76kΩ 1%
Figure 2. C
IN
/C
OUT
use Ceramic Capacitors Application Circuit
C3
0.1μF
R3
100kΩ
4
SHDN
VIN
4.5V to 21V
C1
100μF/25V
EC x 1
C9
0.1μF/25V
CERAMIC x 1
1
BST
LX
6
L1
4.7μH
VOUT
3.3V
R1
30.9kΩ 1%
C2
100μF/6.3V
EC x 1
5
VIN
FR9801
FB
GND
2
3
R2
9.76kΩ 1%
Figure 3. C
IN
/C
OUT
use Electrolytic Capacitors Application Circuit
V
OUT
1.2V
1.8V
2.5V
3.3V
5V
1.2V
1.8V
2.5V
3.3V
5V
C1
10μF MLCC x2
10μF MLCC x2
10μF MLCC x2
10μF MLCC x2
10μF MLCC x2
100μF EC x1
100μF EC x1
100μF EC x1
100μF EC x1
100μF EC x1
R1
R2
C9
--
--
--
--
--
0.1μF
0.1μF
0.1μF
0.1μF
0.1μF
C4
200pF~1nF
200pF~1nF
200pF~1nF
200pF~1nF
200pF~1nF
--
--
--
--
--
L1
C2
22μF MLCC x2
22μF MLCC x2
22μF MLCC x2
22μF MLCC x2
22μF MLCC x2
100μF EC x1
100μF EC x1
100μF EC x1
100μF EC x1
100μF EC x1
4.99kΩ
4.99kΩ
4.99kΩ
30.9kΩ
30.9kΩ
4.99kΩ
4.99kΩ
4.99kΩ
30.9kΩ
30.9kΩ
10kΩ
3.92kΩ
2.32kΩ
9.76kΩ
5.76kΩ
10kΩ
3.92kΩ
2.32kΩ
9.76kΩ
5.76kΩ
2.2μH
2.2μH
4.7μH
4.7μH
4.7μH
2.2μH
2.2μH
4.7μH
4.7μH
4.7μH
Table 1. Recommended Component Values
FR9801-0.5-JUL-2013
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fitipower integrated technology lnc.
FR9801
85T
Functional Pin Description
I/O
I
I
I
I
O
O
GND
LX
BST
Pin Name
FB
VIN
Pin No.
3
5
4
2
6
1
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 0.8V.
Power Supply Input Pin.
Drive VIN pin by 4.5V to 21V voltage to power on the chip.
Enable Input Pin. This pin is a digital control input which turns the converter on or off. Connect to
VIN with a 100kΩ resistor for self-startup.
Ground Pin.
Power Switching Output.
LX is the output of the internal high side NMOS switch.
High Side Gate Drive Boost Pin. A capacitor rating between 10nF~100nF must be connected from
this pin to LX. It can boost the gate drive to fully turn on the internal high side NMOS.
Block Diagram
VIN
SHDN
1M
UVLO
&
POR
ISEN
Internal
Regulator
VCC
OTP
VCC
OVP
Oscillator
BST
S
FB
Current
Comp
R
OTP
OVP
UVLO
PWM
Control
Driver
Logic
High-Side
MOSFET
LX
0.8V
Current
Limit
Low-Side
MOSFET
GND
Figure 4. Block Diagram of FR9801
FR9801-0.5-JUL-2013
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fitipower integrated technology lnc.
FR9801
85T
Absolute Maximum Ratings
(Note 1)
● Supply Voltage V
IN
------------------------------------------------------------------------------------------- -0.3V to +23V
● Enable Voltage
SH
------------------------------------------------------------------------------------- -0.3V to +23V
● LX Voltage V
LX
(50ns) -------------------------------------------------------------------------------------- -1V to V
IN
+0.3V
● BST Pin Voltage V
BST
-------------------------------------------------------------------------------------- V
LX
-0.3V to V
LX
+6V
● All Other Pins Voltage ------------------------------------------------------------------------------------- -0.3V to +6V
● Maximum Junction Temperature (T
J
) ------------------------------------------------------------------ +150°C
● Storage Temperature (T
S
) -------------------------------------------------------------------------------- -65°C to +150°C
● Lead Temperature (Soldering, 10sec.) ---------------------------------------------------------------- +260°C
● Package Thermal Resistance, (θ
JA
)
SOT-23-6
-------------------------------------------------------------------------------------------- +250°C/W
● Package Thermal Resistance, (θ
JC
)
SOT-23-6
-------------------------------------------------------------------------------------------- +110°C/W
Note 1：Stresses beyond this listed under “Absolute Maximum Ratings" may cause permanent damage to the device.
Recommended Operating Conditions
● Supply Voltage V
IN
------------------------------------------------------------------------------------------- +4.5V to +21V
● Operation Temperature Range -------------------------------------------------------------------------- -40°C to +85°C
FR9801-0.5-JUL-2013
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fitipower integrated technology lnc.
FR9801
85T
Electrical Characteristics
(V
IN
=12V, T
A
=25
°C
, unless otherwise specified.)
Parameter
V
IN
Input Supply Voltage
V
IN
Quiescent Current
V
IN
Shutdown Supply Current
Feedback Voltage
Feedback OVP Threshold Voltage
High-Side MOSFET R
DS(ON)
(Note 2)
Low-Side MOSFET R
DS(ON)
(Note 2)
High-Side MOSFET Leakage
Current
High-Side MOSFET Current Limit
(Note 2)
Low-Side MOSFET Current Limit
(Note 2)
Error Amplifier Voltage Gain
(Note 2)
Oscillation Frequency
Short Circuit Oscillation Frequency
Maximum Duty Cycle
Minimum On Time (Note 2)
Input UVLO Threshold
Under Voltage Lockout Threshold
Hysteresis
SH
SH
SH
Input Low Voltage
Input High Voltage
Input Current
Symbol
V
IN
I
DDQ
I
SD
V
FB
V
OVP
R
DS(ON)
R
DS(ON)
I
LX(leak)
I
LIMIT(HS)
I
LIMIT(LS)
SH
SH
SH
Conditions
Min
4.5
Typ
Max
21
Unit
V
mA
=1.8V, V
FB
=1.0V
=0V
0.78
2.5
1
0.8
1.4
120
110
0.82
μA
V
V
mΩ
mΩ
4.5V≦V
IN
≦21V
=0V, V
LX
=0V
2.5
3
10
μA
A
A
V/V
Minimum Duty
From Drain to Source
1.5
400
F
OSC
F
OSC(short)
D
MAX
T
MIN
V
UVLO(Vth)
V
UVLO(HYS)
SH
SH
SH
(L
(H
480
V
FB
=0V
V
FB
=0.6V
600
160
85
100
720
KHz
KHz
%
ns
V
mV
V
IN
Rising
4.3
400
0.4
2
V
V
V
IN
=2V
2
160
μA
°C
Thermal Shutdown Threshold
(Note 2)
Note 2：Not production tested.
T
SD
FR9801-0.5-JUL-2013
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微控制器 MCU
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