FP6161
1.5MHz, 1A Synchronous Step-Down Regulator
General Description
The FP6161 is a high efficiency current mode synchronous buck PWM DC-DC regulator. The
internal generated 0.6V precision feedback reference voltage is designed for low output voltage. Low
RDS (ON) synchronous switch dramatically reduces conduction loss. To extend battery life for portable
application, 100% duty cycle is supported for low-dropout operation. Shutdown mode also helps saving
the current consumption. The FP6161 is packaged in DFN-6L, SOT23-5L, and TSOT23-5L to reduce
PCB space.
Features
Input Voltage Range: 2.5 to 5.5V
Precision Feedback Reference Voltage: 0.6V (±2%)
Output Current: 1A (Max.)
Duty Cycle: 0~100%
Internal Fixed PWM Frequency: 1.5MHz
Low Quiescent Current: 100μA
No Schottky Diode Required
Built-in Soft Start
Current Mode Operation
Over Temperature Protection
Package: DFN-6L (2x2mm), SOT23-5L, TSOT23-5L
Applications
Cellular Telephone
Wireless and DSL Modems
Digital Still Cameras
Portable Products
MP3 Players
Typical Application Circuit
VIN
VIN
SW
VOUT
FP6161
RUN
FB / VOUT
GND
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No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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1/16
FP6161
Function Block Diagram
VCC
Current
Sense
Slope
Compensation
0.6V
FB/
VOUT
UVLO
0.3V
RUN
+
PWM
Comparator
-
+
Error
Amp.
-
Current
Limit
OSC
S
Q
R
Q
Switching
Control Logic
SR Latch
Pre-Driver
and
Anti Shootthrough
+
FBUV
Comparator
-
Reverse
Reverse
Current
Detector
Shutdown
Control
OTP
SW
Reference
Voltage
Generator
GND
Pin Descriptions
DFN-6L
ZYa
986
Name
NC
No. I / O
1
Description
No Connect
RUN
2
I
Enable Pin
VIN
3
P
Power Supply
SW
4
O
Switch
GND
5
P
Ground
FB / VOUT
6
I
Feedback
EP
7
P
Exposed PAD – Must Connect to Ground
SOT23-5L / TSOT23-5L
Name
No. I / O
Description
ZY986
RUN
1
I
Enable
GND
2
P
Ground
SW
3
O
Switch
VIN
4
P
Power Supply
FB / VOUT
5
I
Feedback
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
Website: http://www.feeling-tech.com.tw
2/16
FP6161
Marking Information
DFN-6L
SOT23-5L / TSOT23-5L
Halogen Free: Halogen free product indicator
Lot Number: Wafer lot number’s last two digits
For Example: 132386TB 86
Part Number Code: Part number identification code for this product. It should be always “ZY”.
Year: Production year’s last digit
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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3/16
FP6161
Ordering Information
Part Number
Code
Operating Temperature
Package
MOQ
Description
2500EA
Tape & Reel
FP6161dR-LF-ADJ
ZY
-40°C ~ +85°C
DFN-6L
(2x2mm)
FP6161KR-LF-ADJ
ZY
-40°C ~ +85°C
SOT23-5L
3000EA
Tape & Reel
FP6161iR-LF-ADJ
ZY
-40°C ~ +85°C
TSOT23-5L
3000EA
Tape & Reel
Absolute Maximum Ratings
Max.
Unit
-0.3
6
V
-0.3
VIN
V
P-Channel Switch Source Current (DC)
1.5
A
N-Channel Switch Source Current (DC)
1.5
A
Parameter
Input Supply Voltage
Symbol Conditions
VIN
RUN, VFB, SW Pin Voltage
Min.
Peak SW Switch Sink and Source Current (AC)
Thermal Resistance (Junction to Ambient)
Thermal Resistance (Junction to Case)
θJA
θJC
2
A
DFN-6L
+165
°C / W
SOT23-5L
+250
°C / W
TSOT23-5L
+250
°C / W
DFN-6L
+20
°C / W
SOT23-5L
+90
°C / W
TSOT23-5L
+90
°C / W
+150
°C
+150
°C
DFN-6L
750
mW
SOT23-5L
500
mW
TSOT23-5L
500
mW
+260
°C
Junction Temperature
Storage Temperature
Allowable Power Dissipation
-65
PD
Typ.
Lead Temperature (soldering, 10 sec)
Suggested IR Re-flow Soldering Curve
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
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Rev. 0.67
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4/16
FP6161
Recommended Operating Conditions
Parameter
Symbol
Supply Voltage
Conditions
VIN
Operating Temperature
Min.
Typ.
Max.
Unit
2.5
5.5
V
-40
+85
°C
DC Electrical Characteristics (TA= 25°C, VIN=3.6V, unless otherwise noted)
Parameter
Symbol
Regulated Feedback Voltage
VFB
Min.
Typ.
Max.
Unit
TA=25°C
0.588
0.6
0.612
V
-40°C ~+85°C
0.582
0.6
0.618
V
Conditions
Line Regulation with VREF
VFB
VIN=2.5V to 5.5V
0.04
0.4
/V
Output Voltage Line Regulation
VOUT
VIN=2.5 to 5.5V
0.04
0.4
%/V
RDS (ON) of P-Channel FET
RDS(ON) P ISW=100mA
0.28
0.35
Ω
RDS (ON) of N-Channel FET
RDS (ON) N ISW =-100mA
0.25
0.32
Ω
±0.01
±1
µA
1.5
1.875
A
Shutdown, VRUN=0V
0.1
1
µA
Active, VFB=0.5V, VRUN=VIN
100
SW Leakage
ILSW
VRUN=0V, VIN=5V
Peak Inductor Current
IPK
VFB=0.5V
Quiescent Current
ICC
RUN Threshold
VRUN
RUN Leakage Current
IRUN
Oscillator Frequency
FOSC
1.125
0.3
VFB=0.6V
1.2
µA
1
1.5
V
±0.01
±1
µA
1.5
1.8
MHz
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
Website: http://www.feeling-tech.com.tw
5/16
FP6161
Typical Operating Characteristics
(TA= 25°C, VIN=3.6V, unless otherwise noted)
Supply Current vs. VIN
Supply Current vs. VIN
100
24
VFB=0.5V
VFB=0.7V
23
Supply Current (µA)
Supply Current (µA)
95
90
85℃
85
-45℃
80
25℃
75
22
85℃
21
25℃
20
-45℃
19
70
65
18
2
3
4
5
6
2
3
4
VIN (V)
5
6
VIN (V)
Line Regulation
Supply Current vs. VIN
0.61
18
TA=25℃
Shutdown
Reference Voltage (V)
Supply Current (nA)
16
14
12
85℃
10
8
6
4
25℃
2
0.6
0.595
0.59
-45℃
0
2
0.605
3
4
5
0.585
6
2
3
4
VIN (V)
Reference Voltage vs. Temperature
6
Frequency vs. VIN
0.605
1.56
VIN=3.6V
0.604
VI N=3.6V
1.54
0.603
0.602
Frequency (MHz)
Reference Voltage (V)
5
VIN (V)
0.601
0.6
0.599
0.598
0.597
1.52
1.5
1.48
1.46
0.596
1.44
0.595
-60 -50 -40 -30 -20 -10
0
2
10 20 30 40 50 60 70 80 90
3
4
Temperature (℃)
6
Switch Leakage vs. Input Volatge
Frequency vs. Temerature
1.58
1.2
TA=25℃
1.56
TA=25℃
1
Switch Leakage (nA)
1.54
Frequency (MHz)
5
VIN (V)
1.52
1.5
1.48
1.46
1.44
0.8
0.6
Synchronous Switch
0.4
Main Switch
0.2
1.42
0
1.4
-50 -40 -30 -20 -10
0
10
20
30
40
50
60
70
80
1
90
2
3
4
5
6
7
VIN (V)
Temperature (℃)
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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6/16
FP6161
Function Description
Control Loop
The FP6161 is a high efficiency current mode synchronous buck regulator. Both the main
(P-channel MOSFET) and synchronous (N-channel MOSFET) switches are built internally.
With
current mode operation, the PWM duty is controlled both by the error amplifier output and the peak
inductor current. At the beginning of each cycle, the oscillator turn on the P-MOSFET switch to
source current from VIN to SW output. Then, the chip starts to compare the inductor current with the
error amplifier output.
Once the inductor current is larger than the error amplifier output, the
P-MOSFET switch is turned off. When the load current increases, the feedback voltage FB will
slightly drop. This causes the error amplifier to output a higher current level until the prior mentioned
peak inductor current reach the same level. The output voltage then can be sustained at the same.
When the top P-MOSFET switch is off, the bottom synchronous N-MOSFET switch is turned on.
Once the inductor current reverses, both top and bottom MOSFET will be turn off to leave the SW pin
into high impedance state.
The FP6161’s current mode control loop also includes slope compensation to suppress
sub-harmonic oscillations at high duty cycles. This slope compensation is achieved by adding a
compensation ramp to the inductor current signal.
LDO Mode
The FP6161’s maximum duty cycle can reach 100%. That means the driver’s main switch is
turn on through out whole clock cycle. Once the duty reaches 100%, the feedback path no longer
controls the output voltage. The output voltage will be the input voltage minus the main switch
voltage drop.
Over Current Protection
FP6161 limits the peak main switch current cycle by cycle. When over current occurs, chip will
turn off the main switch and turn the synchronous switch on until next cycle.
Short Circuit Protection
When the FB pin drops below 300mV, the chip will tri-state the output pin SW automatically. After
300us rest to avoid over heating, chip will re-initiate PWM operation with soft start.
Thermal Protection
FP6161 will shutdown automatically when the internal junction temperature reaches 150℃ to
protect both the part and the system.
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
Website: http://www.feeling-tech.com.tw
7/16
FP6161
Application Information
Input Capacitor Selection
The input capacitor must be connected to the VIN pin and GND pin of FP6161 to maintain steady
input voltage and filter out the pulsing input current. The voltage rating of input capacitor must be
greater than maximum input voltage plus ripple voltage.
In switch mode, the input current is discontinuous in a buck converter. The source current
waveform of the high-side MOSFET is a square wave. To prevent large voltage transients, a low ESR
input capacitor sized for the maximum RMS current must be used. The RMS value of input capacitor
current can be calculated by:
IRMS IOMAX
VO
VIN
V
1 O
VIN
It can be seen that when VO is half of VIN, CIN is under the worst current stress. The worst current
stress on CIN is IO_MAX / 2.
Inductor Selection
The value of the inductor is selected based on the desired ripple current. Large inductance gives
low inductor ripple current and small inductance result in high ripple current. However, the larger value
inductor has a larger physical size, higher series resistance, and / or lower saturation current. In
experience, the value is to allow the peak-to-peak ripple current in the inductor to be 10%~20%
maximum load current. The inductance value can be calculated by:
L
( VIN VO ) VO
( VIN VO )
VO
f IL VIN f 2 (10% ~ 20%)IO VIN
The inductor ripple current can be calculated by:
IL
V
VO
1 O
f L
VIN
Choose an inductor that does not saturate under the worst-case load conditions, which is the
load current plus half the peak-to-peak inductor ripple current, even at the highest operating
temperature. The peak inductor current is:
IL _ PEAK IO
IL
2
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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8/16
FP6161
The inductors in different shape and style are available from manufacturers. Shielded inductors
are small and radiate less EMI issue. But they cost more than unshielded inductors. The choice
depends on EMI requirement, price and size.
Inductor Value (µH)
Dimensions
Component Supplier
Model
2.2
2.2
3.3
4.7
4.7
4.7
4.2×3.7×1.2
4.4×5.8×1.2
4.2×3.7×1.2
4.2×3.7×1.2
4.4×5.8×1.2
4.9×4.9×1.0
FENG-JUI
Sumida
FENG-JUI
FENG-JUI
Sumida
Sumida
TP4212-2R2M
CMD4D11 2R2
TP4212-3R3M
TP4212-4R7M
CMD4D11 4R7
CLSD09 4R7
Output Capacitor Selection
The output capacitor is required to maintain the DC output voltage. Low ESR capacitors are
preferred to keep the output voltage ripple low. In a buck converter circuit, output ripple voltage is
determined by inductor value, switching frequency, output capacitor value and ESR. The output ripple
is determined by:
1
VO IL ESR COUT
8
f
C OUT
Where f = operating frequency, COUT= output capacitance and ΔIL = ripple current in the inductor.
For a fixed output voltage, the output ripple is highest at maximum input voltage since ΔIL increases
with input voltage.
Capacitor Value (µF)
Case Size
Component Supplier
Model
4.7
10
10
22
0603
0805
0805
0805 1206
TDK
Taiyo Yuden
TDK
TDK
C1608JB0J475M
JMK212BJ106MG
C12012X5ROJ106K
C2012JB0J226M
Using Ceramic Input and Output Capacitors
Care must be taken when ceramic capacitors are used at the input and the 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 current through the long wires can
potentially cause a voltage spike at VIN, which may large enough to damage the part. When choosing
the input and output ceramic capacitors, choose the X5R or X7R specifications. Their dielectrics have
the best temperature and voltage characteristics of all the ceramics for a given value and size.
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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9/16
FP6161
Output Voltage Programming
In the adjustable version, the output voltage is set using a resistive voltage divider from the output
voltage to FB. The output voltage is:
R
VO 0.6 V 1 1
R2
The recommended resistor value is summarized below:
VOUT (V)
R1 (Ω)
R2 (Ω)
C3 (F)
0.6
1.2
1.5
1.8
2.5
3.3
200k
200k
300k
200k
270k
306k
Not Used
200k
200k
100k
85k
68k
Not Used
10p
10p
10p
10p
10p
PC Board Layout Checklist
1. The power traces, consisting of the GND, SW and VIN trace should be kept short, direct and
wide.
2. Place CIN near VIN pin as closely as possible to maintain input voltage steady and filter out the
pulsing input current.
3. The resistive divider R1 and R2 must be connected to FB pin directly and as closely as possible.
4. FB is a sensitive node. Please keep it away from switching node, SW. A good approach is to
route the feedback trace on another PCB layer and have a ground plane between the top and
feedback trace routing layer. This reduces EMI radiation on to the DC-DC converter its own
voltage feedback trace.
5. Keep the GND plates of CIN and COUT as close as possible. Then connect this to the ground
plane (if one is used) with several vias. This reduces ground plane noise by preventing the
switching currents from circulating through the ground plane. It also reduces ground bounce at
FP6161 by giving it a low impedance ground connection.
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
Website: http://www.feeling-tech.com.tw
10/16
FP6161
Suggested Layout for SOT23-5L
Suggested Layout for DFN-6L
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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11/16
FP6161
Typical Application
L1 3.3uH
VIN
VIN
2.5V~5.5V
SW
R1
270K
FP6161
C1
10µF
1
VOUT
2.5V/1A
3
4
RUN
FB / VOUT
C3
10pF
C2
10µF
5
R2
85K
GND
2
SOT23-5L / TSOT23-5L
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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12/16
FP6161
ILOAD: 200mA~1A
ILOAD: 100mA~1A
Ch1:VOUT
Ch2: ISW
Ch1: VOUT
EN On waveform (VOUT: 1.8V)
Ch2: ISW
Efficiency (VOUT: 2.5V)
Efficiency VS. Output Current
100
90
80
Efficiency (%)
70
60
Vin=2.7V
50
Vin=3.6V
40
Vin=4.2V
30
20
10
0
0.1
Ch1: EN Ch2: SW
1.0
10.0
Output Current (mA)
100.0
1000.0
Ch3: VOUT Ch4: ISW
Efficiency (VIN: 5.3V)
Efficiency VS Output Current
100
90
80
Efficiency (%)
70
60
Vout=3.3V
50
Vout=1.8V
40
Vout=1.2V
30
20
10
0
0.1
1.0
10.0
100.0
Output Current (mA)
1000.0
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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13/16
FP6161
Package Outline
DFN-6L
Unit: MM
Symbols
Min. (mm)
Max. (mm)
A
0.700
0.800
A1
0.000
0.050
b
0.200
0.300
c
0.190
0.250
D
1.950
2.050
D2
1.350
1.450
E
1.950
2.050
E2
0.750
0.850
e
0.650 REF
L
0.300
0.400
y
0.000
0.075
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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14/16
FP6161
SOT23-5L
Unit: MM
Symbols
Min. (mm)
Max.(mm)
A
1.050
1.350
A1
0.050
0.150
A2
1.000
1.200
b
0.250
0.500
c
0.080
0.200
D
2.700
3.000
E
2.600
3.000
E1
1.500
1.700
e
0.950 BSC
e1
1.900 BSC
L
0.300
0.550
L1
0.600 REF
L2
0.250 BSC
θ°
0°
10°
θ1°
3°
7°
θ2°
6°
10°
Note:
1. Package dimensions are in compliance with JEDEC outline: MO-178 AA.
2. Dimension “D” does not include molding flash, protrusions or gate burrs.
3. Dimension “E1” does not include inter-lead flash or protrusions.
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
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15/16
FP6161
TSOT23-5L
Unit: MM
Symbols
Min.(mm)
Max.(mm)
A
0.750
0.800
A1
0.000
0.050
A2
0.700
0.775
b
0.350
0.500
c
0.100
0.200
D
2.800
3.000
E
2.600
3.000
E1
1.500
1.700
e
0.950 BSC
e1
1.900 BSC
L
Note:
0.370
0.600
L1
0.600 REF
L2
0.250 BSC
R
0.100
R1
0.100
0.250
θ°
0°
8°
θ1
4°
12°
1. Dimension “D” does not include molding flash, protrusions or gate burrs.
2. Dimension “E1” does not include inter-lead flash or protrusions.
This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.
No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.
Rev. 0.67
Website: http://www.feeling-tech.com.tw
16/16
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