FR9702S9G [FITIPOWER]
23V, 1.8A, 1.4MHz Asynchronous Step-Down DC/DC Converter;
| 型号： | FR9702S9G |
| 厂家： | 
Fitipower |
| 描述： | 23V, 1.8A, 1.4MHz Asynchronous Step-Down DC/DC Converter |
| 文件： | 总14页 (文件大小：753K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
fitipower integrated technology lnc.
FR9702
23V, 1.8A, 1.4MHz Asynchronous Step-Down
DC/DC Converter
Description
Features
The FR9702 is a monolithic step-down switch mode
converter with a built-in power MOSFET. It
achieves 1.8A output current over a wide input
supply range with excellent load and line regulation.
Current mode operation provides fast transient
● 1.8A Output Current
● 180mΩ Internal Power MOSFET Switch
● Stable with Low ESR Output Ceramic Capacitors
● Up to 92% Efficiency
● Fixed 1.4MHz Frequency
response and eases loop stabilization.
Fault
● Current Mode Operation
condition protection includes cycle-by-cycle current
limit and over temperature protection.
● Over-Temperature Protection with Hiccup-Mode
● Cycle-by-Cycle Over Current Protection
● Wide 4.5V to 23V Operating Input Range
● Output Adjustable from 0.805V to 15V
● 10μA Shutdown Current
● Miniature Packages:
SOT-23-6, TSOT23-6, MSOP-10 and SOP-8
(Exposed Pad)
The FR9702 requires a minimum number of
available standard external components.
The
FR9702 is available in SOT23-6, TSOT23-6,
MSOP-10 and SOP-8 (Exposed Pad) packages.
Applications
● Battery Charger
● Pre-Regulator for Linear Regulator
● OLPC, Netbook
● Distributed Power System
● WLED Driver
Pin Assignments
Ordering Information
FR9702□□□
S6 Package (SOT-23-6)
SW
EN
VIN
TR: Tape/Reel
G: Green
6
5
4
(Marking)
2
1
3
BS GND FB
S9 Package (TSOT-23-6)
Package Type
SW
EN
4
S6: SOT-23-6
S9: TSOT-23-6
MS: MSOP-10
SP: SOP-8 (Exposed Pad)
VIN
6
5
(Marking)
2
1
3
SOT-23-6 Marking
BS GND FB
Part Number
Product Code
t9G
MS Package (MSOP-10)
FR9702S6G
10
9
1
2
NC
BS
NC
EN
8
NC
FB
3
4
5
NC
VIN
SW
TSOT-23-6 Marking
Part Number
7
6
GND
Product Code
S1G
SP Package SOP-8 (Exposed Pad)
FR9702S9G
8
7
6
5
1
2
BS
VIN
NC
EN
NC
FB
3
4
SW
GND
Figure 1. Pin Assignment of FR9702
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FR9702
Typical Application Circuit
5
1
6
VIN
4.5V to 23V
VIN
BS
C3
22nF
C1
10μF/25V
CERAMIC
L1 4.7μH
SW
VOUT
FR9702
3.3V
D1
B230A
C4(optional)
10nF
R1
30.9KΩ/1%
3
4
FB
EN
C2
22μF/6.3V
CERAMIC
OFF ON
GND
2
R2
10KΩ/1%
Figure 2. Output 3.3V Application Circuit
Functional Pin Description
Pin Name
Pin Function
Bootstrap. A 22nF capacitor is connected between SW and BS pins to drive the power switch’s gate above the
supply voltage.
BS
GND
FB
Ground Pin. Connect this pin to exposed pad.
Feedback. An external resistor divider from the output to GND, tapped to the FB pin sets the output voltage.
On/Off Control Input. Pull EN above 1.2V and below 5V to turn the device on.
EN
Power Supply Input. Drive 4.5V to 23V voltage to this pin to power on this chip. Connect a 10μF ceramic bypass
capacitor between VIN and GND to eliminate noise.
VIN
SW
NC
Switch Output. Connect this pin to the switch end of the inductor.
No Connect.
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FR9702
Block Diagram
VIN
Internal
Regulator
UVLO
&
POR
OVP
OTP
VCC
VCC
ISEN
EN
950K
BS
Oscillator
Current
High-Side
MOSFET
S
R
Comparator
Error
Driver
Logic
PWM
Control
Amplifier
SW
FB
OVP
OTP
UVLO
CCOMP
RCOMP
0.805V
Current
Limit
GND
Figure 3. Block Diagram of FR9702
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FR9702
Absolute Maximum Ratings
● Input Supply Voltage (VIN) --------------------------------------------------------------------------------- +25V
● VSW -------------------------------------------------------------------------------------------------------------- -0.3V to VIN +0.3V
● VBS --------------------------------------------------------------------------------------------------------------- Vsw +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)
SOT-23-6 ------------------------------------------------------------------------------------------- +0.4W
TSOT-23-6 ----------------------------------------------------------------------------------------- +0.4W
MSOP-10 ------------------------------------------------------------------------------------------ +0.63W
SOP-8 (Exposed Pad) -------------------------------------------------------------------------- +1.25W
● Package Thermal Resistance, (θJA)
SOT-23-6 ------------------------------------------------------------------------------------------- 250°C/W
TSOT-23-6 ----------------------------------------------------------------------------------------- 250°C/W
MSOP-10 ------------------------------------------------------------------------------------------ 160°C/W
SOP-8 (Exposed Pad) -------------------------------------------------------------------------- 50°C/W
● Package Thermal Resistance, (θJC)
SOP-8 (Exposed Pad) -------------------------------------------------------------------------- 10.4°C/W
● ESD Susceptibility
HBM(Human Body Mode)------------------------------------------------------------------------------
2KV
Note 1：Stresses exceed those ratings may damage the device.
Recommended Operating Conditions
● Input Supply Voltage (VIN) --------------------------------------------------------------------------------- +4.5V to +23V
● Output Voltage (VOUT) --------------------------------------------------------------------------------------- +0.805V to +15V
● Operation Temperature Range --------------------------------------------------------------------------- -40°C to +85°C
Note 2：If out of its operation conditions, the device is not guaranteed to function.
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FR9702
Electrical Characteristics
(VIN=12V, TA=25°C, unless otherwise specified.)
Parameter
Test Conditions
4.5V ≤ VIN ≤ 23V
Min
Typ
0.805
180
Max
Unit
V
Feedback Voltage
0.785
0.825
Switch-On Resistance (*)
Switch Leakage
mΩ
μA
A
VEN = 0V, VSW = 0V
10
Current Limit (*)
3
Oscillator Frequency
1.2
1.4
460
85
1.7
MHz
KHz
%
Fold-back Frequency
VFB = 0V
Maximum Duty Cycle
Minimum On-Time (*)
100
4.4
250
ns
Under Voltage Lockout Threshold Rising
Under Voltage Lockout Threshold Hysteresis
EN Input Low Voltage
4.1
1.2
4.7
0.4
V
mV
V
EN Input High Voltage
V
VEN = 2V
2.0
0.1
10
μA
μA
μA
mA
°C
EN Input Current
VEN = 0V
Supply Current (Shutdown)
VEN = 0V
Supply Current (Quiescent)
VEN = 2V, VFB = 1V
1.8
150
Over-Temperature Protection Threshold (*)
* Guaranteed by design
Note 3：VIN = 5V, VOUT = 3.3V, maximum load current is about 1.4A.
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Typical Performance Curves
VIN = 12V, VOUT = 3.3V, C1 = 10μF, C2 = 22μF, L1 = 4.7μH, TA = +25°C, unless otherwise noted.
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
VIN= 12V
VIN= 23V
VIN= 23V
VIN= 12V
VIN= 5V
VOUT= 5V
VOUT= 3.3V
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Load current (A)
Load current (A)
Figure 4. Efficiency vs. Loading
Figure 5. Efficiency vs. Loading
1.6
0.816
0.814
0.812
0.81
1.55
1.5
IOUT= 0.2A
IOUT= 0.2A
1.45
1.4
0.808
0.806
0.804
0.802
0.8
1.35
1.3
1.25
1.2
0.798
0.796
-40 -30 -20 -10
0
10
20
30
40
50
60
70
80
90 100
-40 -30 -20 -10
0
10
20
30
40
50
60
70
80
90 100
Case Temperature (℃)
Case Temperature (℃)
Figure 6. Feedback Voltage vs. Case Temperature
Figure 7.Switching Frequency vs. Case Temperature
IOUT = 0.2A
IOUT = 1.8A
VIN 50mV/div.
VOUT 10mV/div.
VIN 100mV/div.
VOUT 10mV/div.
IL 0.5A/div.
IL 0.5A/div.
VSW 5V/div.
400ns/div.
VSW 5V/div.
400ns/div.
Figure 8. DC Ripple Waveform
Figure 9. DC Ripple Waveform
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Typical Performance Curves (Continued)
VIN = 12V, VOUT = 3.3V, C1 = 10μF, C2 = 22μF, L1 = 4.7μH, TA = +25°C, unless otherwise noted.
IOUT=0.2A
IOUT=1.8A
VEN, 5V/div.
VEN, 5V/div.
VOUT 1V/div.
VOUT 1V/div.
IL 1A/div.
IL 1A/div.
VSW 5V/div.
VSW 5V/div.
40μs/div.
40μs/div.
Figure 10. Startup Through Enable Waveform
IOUT=0.2A
Figure 11. Startup Through Enable Waveform
IOUT=1.8A
VEN, 5V/div.
VEN, 5V/div.
VOUT 1V/div.
VOUT 1V/div.
IL 1A/div.
IL 1A/div.
VSW 5V/div.
VSW 5V/div.
200μs/div.
40μs/div.
Figure 12. Shutdown Through Enable Waveform
IOUT = 200mA to 1.8A step
VOUT 100mV/div.
Figure 13. Shutdown Through Enable Waveform
VOUT 1V/div.
IL 1A/div.
IL 1A/div.
20μs/div.
400μs/div.
Figure 14. Load Transient Waveform
Figure 15. Short Circuit Test
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Application Information
Setting EN Automatic Startup Voltage
Table 2 -- Resistor Selection for Common
Output Voltages
VIN
VOUT
R1
R2
5V
43kΩ
30.9kΩ
21kΩ
8.2kΩ
10kΩ
10kΩ
10kΩ
10kΩ
R3
FR9702
EN
5V
3.3V
2.5V
1.8V
1.2V
950KΩ
R4
12.4kΩ
4.99kΩ
The external resistor divider is used to set the EN
automatic startup voltage:
Selecting the Inductor
VEN
A 4.ꢃμH inductor with a DC current rating of at
least 25% percent higher than the maximum load
current is recommended for most applications.
For highest efficiency, the inductor’s DC
resistance should be less than 200mΩ. For
most designs, the required inductance value can
be derived from the following equation.
R4ꢀ
VINꢁV
ENꢀ
R3
For example, VIN=12V, R3ꢀ100KΩ, thus R4 resistor
value is:
5V
R4ꢀ
ꢂꢃ1.5kΩ
12Vꢁ5V
100kΩ
ꢆIꢀ0.3ꢄIL(MAXꢇ
ꢀ
VOUT
FSWꢄꢆIꢄVIN
Table 1 shows a list of resistor selection for common
input voltages:
ꢁ
ꢃ
Lꢈ VINꢂVOUT ꢄ
ꢀ
Table 1 -- Resistor Selection for Common Input
Voltages
Where ΔI is the inductor ripple current.
VIN
R3
R4
Choose the inductor ripple current to be 30% of
the maximum load current.
inductor peak current is calculated from:
The maximum
5V
100kΩ
100kΩ
100kΩ
NC
12V
16V
71.5kΩ
45.3kΩ
ꢆIL
IL(MAXꢇꢀILOAD
ꢅ
2
Setting Output Voltage
The external resistor divider is used to set the output
voltage. FR9702 feedback resistors are
Under light load conditions below 100mA, a larger
inductance is recommended for improving
efficiency.
unconcerned of compensation and provide an easy
way to program output voltage. Table 2 shows a list
of resistor selection for common output voltages:
R1
VOUTꢀ0.805ꢄ 1ꢅ ꢀ V
R2
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Application Information (Continued)
Selecting the Input Capacitor
Rectifier Diode
The input capacitor reduces the surge current drawn
from the input supply and the switching noise from
the device. The input capacitor impedance at the
switching frequency should be less than the input
source impedance to prevent high frequency
switching current from passing through the input.
Ceramic capacitors with X5R or X7R dielectrics are
highly recommended because of their low ESR and
Use a Schottky diode as the rectifier to conduct
current when the high-side power MOSFET is off.
The Schottky diode must have current rating higher
than the maximum output current and the reverse
voltage rating higher than the maximum input
voltage.
PCB Layout Recommendation
small
temperature
coefficients.
For
most
The device’s performance and stability are
applications, a 10μF capacitor is sufficient.
dramatically affected by PCB layout.
It is
recommended to follow these general guidelines
shown as below:
Selecting the Output Capacitor
The output capacitor keeps the output voltage ripple
small, and a 22μF ceramic capacitor with X5R or
X7R dielectrics is recommended for its low ESR
characteristics.
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.
External Bootstrap Diode
2. Place VIN capacitors close to the VIN pin.
An external bootstrap diode is recommended if the
input voltage is less than 5V or if there is a 5V system
3. Place feedback resistors close to the FB pin.
rail available.
This diode helps improving the
4. Keep the sensitive signal (FB) away from the
switching signal (SW).
efficiency. Low cost diodes, such as 1N4148, are
suitable for this application.
D2
1N4148
VIN
5V
VIN
BS
FR9702
C3
SW
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FR9702
Application Information (Continued)
VIN
SW
L1
VOUT
C2
C1
6
1
5
4
D1
GND
2
3
R2
R1
Figure 16. FR9702 (SOT-23-6 and TSOT-23-6) Recommended Layout Diagram
R3
R4
R1
R2
10
9
8
GND
3
7
6
C1
C2
D1
4
5
1
2
VIN
SW
L1
VOUT
C3
Figure 17. FR9702 (MSOP-10) Recommended Layout Diagram
R3
R1
R4
R2
8
1
7
6
5
Exposed
Pad
C2
C1
4
2
3
D1
VIN
VOUT
SW
L1
C3
Figure 18. FR9702 (SOP-8 Exposed Pad ) Recommended Layout Diagram
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FR9702
Outline Information
SOT-23-6 Package (Unit: mm)
DIMENSION IN MILLIMETER
SYMBOLS
UNIT
MIN
0.90
0.00
0.90
0.30
2.80
2.60
1.50
0.90
1.80
0.30
MAX
1.45
0.15
1.30
0.50
3.00
3.00
1.70
1.00
2.00
0.60
A
A1
A2
B
D
E
E1
e
e1
L
Note：Followed From JEDEC MO-178-C.
Carrier Dimensions
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FR9702
Outline Information (Continued)
TSOT-23-6 Package (Unit: mm)
DIMENSION IN MILLIMETER
SYMBOLS
UNIT
MIN
0.70
0.00
0.70
0.30
2.80
2.60
1.50
0.90
1.80
0.30
MAX
1.10
0.10
1.00
0.50
3.00
3.00
1.70
1.00
2.00
0.60
A
A1
A2
B
D
E
E1
e
e1
L
Carrier Dimensions
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FR9702
Outline Information (Continued)
MSOP-10 Package (Unit: mm)
DIMENSION IN MILLIMETER
SYMBOLS
UNIT
MIN
0.75
0.00
0.75
0.17
2.90
4.80
2.90
0.40
0.40
MAX
1.10
0.15
0.95
0.33
3.10
5.00
3.10
0.60
0.80
A
A1
A2
B
D
E
E1
e
L
Carrier Dimensions
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FR9702
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.
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