NCP3170
Synchronous PWM
Switching Converter
The NCP3170 is a flexible synchronous PWM Switching Buck
Regulator. The NCP3170 operates from 4.5 V to 18 V, sourcing up to
3 A and is capable of producing output voltages as low as 0.8 V.
The NCP3170 also incorporates current mode control. To reduce the
number of external components, a number of features are internally set
including soft start, power good detection, and switching frequency.
The NCP3170 is currently available in an SOIC−8 package.
Features
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SOIC−8 NB
CASE 751
4.5 V to 18 V Operating Input Voltage Range
90 mW High-Side, 25 mW Low-Side Switch
FMEA Fault Tolerant During Pin Short Test
3 A Continuous Output Current
Fixed 500 kHz and 1 MHz PWM Operation
Cycle-by-Cycle Current Monitoring
1.5% Initial Output Accuracy
Internal 4.6 ms Soft-Start
Short-Circuit Protection
Turn on Into Pre-bias
Power Good Indication
Light Load Efficiency
Thermal Shutdown
These are Pb-Free Devices
Set Top Boxes
DVD/Blu−rayt Drives and HDD
LCD Monitors and TVs
Cable Modems
PCIe Graphics Cards
Telecom/Networking/Datacom Equipment
Point of Load DC/DC Converters
MARKING DIAGRAM
8
3170x
ALYW
G
1
3170x
x
A
L
Y
W
G
= Specific Device Code
= A or B
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb-Free Package
PIN CONNECTIONS
Typical Applications
PGND
V
IN
AGND
FB
(Top View)
V
SW
PG
EN
COMP
ORDERING INFORMATION
Device
NCP3170ADR2G
Package
SOIC−8
(Pb−Free)
SOIC−8
(Pb−Free)
Shipping
†
2,500/Tape & Reel
2,500/Tape & Reel
V
IN
C1
22
mF
EN
NCP3170
PG
COMP
C
C
AGND
R
C
PGND
FB1
R2
R1
C2, C3
22
mF
VIN
VSW
3.3 V
L1 4.7
mH
NCP3170BDR2G
†For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specifications
Brochure, BRD8011/D.
Figure 1. Typical Application Circuit
©
Semiconductor Components Industries, LLC, 2014
1
March, 2017 − Rev. 6
Publication Order Number:
NCP3170/D
NCP3170
VIN
VDD
EN
UVLO
POR
Power
Control
(PC)
Driver
Voltage
Clamp
VCV
VCL
Reference
ORing
Circuit
Soft Start
S
Slope
Compensation
0.030 V/A
Current
Sense
S
SET
Q
R
CLR
Q
−
−
Pulse by
Pulse
Current
Limit
Oscillator
FB
+
+
COMP
VIN
Soft Start
Complete
+
−
+
−
+
−
Logic
HS
PDRV
VCW
VSW
998 mV
hs
VCL
LS
NDRV
867 mV
728 mV
PG
Over
Temperature
Protection
Zero
Current
Detection
VSW
AGND
PGND
Figure 2. NCP3170 Block Diagram
Table 1. PIN FUNCTION DESCRIPTION
Pin
1
2
Pin Name
PGND
VIN
Description
The power ground pin is the high current path for the device. The pin should be soldered to a large copper
area to reduce thermal resistance. PGND needs to be electrically connected to AGND.
The input voltage pin powers the internal control circuitry and is monitored by multiple voltage comparators.
The VIN pin is also connected to the internal power PMOS switch and linear regulator output. The VIN pin
has high di/dt edges and must be decoupled to ground close to the pin of the device.
The
analog ground
pin serves as small-signal ground. All small-signal ground paths should connect to the
AGND
pin and should also be electrically connected to power ground at a single point, avoiding any high
current ground returns.
Inverting input to the OTA error amplifier. The FB pin in conjunction with the external compensation serves to
stabilize and achieve the desired output voltage with current mode compensation.
The loop compensation pin is used to compensate the transconductance amplifier which stabilizes the
operation of the converter stage. Place compensation components as close to the converter as possible.
Connect a RC network between COMP and AGND to compensate the control loop.
Enable pin. Pull EN to logic high to enable the device. Pull EN to logic low to disable the device. Do not leave
it open.
Power good is an open drain 500
mA
pull down indicating output voltage is within the power good window. If
the power good function is not used, it can be connected to the VSW node to reduce thermal resistance. Do
not connect PG to the VSW node if the application is turning on into pre-bias.
The VSW pin is the connection of the drains of the internal N and P MOSFETS. At switch off, the inductor will
drive this pin below ground as the body diode and the NMOS conducts with a high dv/dt.
3
AGND
4
5
FB
COMP
6
7
EN
PG
8
VSW
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NCP3170
Table 2. ABSOLUTE MAXIMUM RATINGS
(measured vs. GND pin 3, unless otherwise noted)
Rating
Main Supply Voltage Input
Voltage between PGND and AGND
PWM Feedback Voltage
Error Amplifier Voltage
Enable Voltage
PG Voltage
VSW to AGND or PGND
VSW to AGND or PGND for 35ns
Junction Temperature (Note 1)
Operating Ambient Temperature Range
Storage Temperature Range
Thermal Characteristics (Note 2)
SOIC−8 Plastic Package
Maximum Power Dissipation @ T
A
= 25°C
Thermal Resistance Junction-to-Air
Thermal Resistance Junction-to-Case
Lead Temperature Soldering (10 sec):
Reflow (SMD Styles Only) Pb-Free (Note 3)
Symbol
V
IN
V
PAG
F
B
COMP
EN
PG
V
SW
V
SWST
T
J
T
A
T
stg
V
MAX
20
0.3
6
6
V
IN
+ 0.3 V
V
IN
+ 0.3 V
V
IN
+ 0.3 V
V
IN
+ 10 V
+150
−40 to +85
− 55 to +150
V
MIN
−0.3
−0.3
−0.3
−0.3
−0.3
−0.3
−0.7
−5
Unit
V
V
V
V
V
V
V
V
°C
°C
°C
P
D
R
qJA
RqJC
RF
1.15
87
37.8
260 peak
W
°C/W
°C/W
°C
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
1. The maximum package power dissipation limit must not be exceeded.
P
D
+
T
J(max)
*
T
A
R
qJA
2. The value of
qJA
is measured with the device mounted on 2in x 2in FR−4 board with 2oz. copper, in a still air environment with T
A
= 25°C.
The value in any given application depends on the user’s specific board design.
3. 60−180 seconds minimum above 237°C.
Table 3. RECOMMENDED OPERATING CONDITIONS
Rating
Main Supply Voltage Input
Power Good Pin Voltage
Switch Pin Voltage
Enable Pin Voltage
Comp Pin Voltage
Feedback Pin Voltage
Power Ground Pin Voltage
Junction Temperature Range
Operating Temperature Range
Symbol
VIN
PG
V
SW
EN
COMP
FB
PGND
T
J
T
A
Min
4.5
0
−0.3
0
−0.1
−0.1
−0.1
−40
−40
Max
18
18
18
18
5.5
5.5
−0.1
125
85
Unit
V
V
V
V
V
V
V
°C
°C
Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond
the Recommended Operating Ranges limits may affect device reliability.
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NCP3170
Table 4. ELECTRICAL CHARACTERISTICS
(T
A
= 25°C, V
IN
= V
EN
= 12 V, V
OUT
= 3.3 V for min/max values unless otherwise noted (Note 7))
Characteristic
Input Voltage Range
SUPPLY CURRENT
Quiescent Supply Current
Shutdown Supply Current
UNDER VOLTAGE LOCKOUT
VIN UVLO Threshold
VIN UVLO Threshold
MODULATOR
Oscillator Frequency
Maximum Duty Ratio
Minimum Duty Ratio
VIN Soft Start Ramp Time
OVER CURRENT
Current Limit
PWM COMPENSATION
VFB Feedback Voltage
Line Regulation
GM
AOL DC gain
Unity Gain BW (C
OUT
= 10 pF)
Input Bias Current (Current Out of FB IB Pin)
IEAOP Output Source Current
IEAOM Output Sink Current
ENABLE
Enable Threshold
POWER GOOD
Power Good High On Threshold
Power Good High Off Threshold
Power Good Low On Threshold
Power Good Low Off Threshold
Over Voltage Protection Threshold
Power Good Low Voltage
PWM OUTPUT STAGE
High-Side Switch On-Resistance
Low-Side Switch On-Resistance
THERMAL SHUTDOWN
Thermal Shutdown
Hysteresis
(Notes 4 and 6)
−
−
164
43
−
−
°C
°C
V
IN
= 12 V
V
IN
= 4.5 V
V
IN
= 12 V
V
IN
= 4.5 V
−
−
−
−
90
100
25
29
130
150
35
39
mW
mW
V
IN
= 12 V, IPG = 500
mA
−
−
−
−
−
−
875
859
712
728
998
0.195
−
−
−
−
−
−
mV
mV
mV
mV
mV
V
(Note 5)
−
1.41
−
V
(Note 4)
(Note 4)
(Note 4)
V
FB
= 0 V
V
FB
= 2 V
T
A
= 25°C
(Note 4)
0.792
−
−
40
2.0
−
−
−
0.8
1
201
55
−
−
20.1
21.3
0.808
−
−
−
−
286
−
−
V
%
mS
dB
MHz
nA
mA
mA
(Note 4)
4.0
−
6.0
A
NCP3170A
NCP3170B
NCP3170A
NCP3170B
NCP3170A
NCP3170B
V
IN
= 12 V
V
FB
= VCOMP
Enable = V
IN
450
900
91
90
6.0
4.0
3.5
500
1000
−
−
−
−
4.6
550
1100
96
96
11
11.5
6.0
kHz
%
%
ms
V
IN
Rising Edge (Note 5)
V
IN
Falling Edge (Note 5)
−
−
4.41
4.13
−
−
V
V
NCP3170A
NCP3170B
V
IN
= EN = 12 V V
FB
= 0.8 V
(Note 5)
EN = 0 V (Note 5)
−
−
−
1.7
1.7
13
2.0
2.0
17
mA
mA
Conditions
(Note 5)
Min
4.5
Typ
−
Max
18
Unit
V
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product
performance may not be indicated by the Electrical Characteristics if operated under different conditions.
4. Guaranteed by design
5. Ambient temperature range of −40°C to +85°C.
6. This is not a protection feature.
7. The device is not guaranteed to operate beyond the maximum operating ratings.
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NCP3170
TYPICAL PERFORMANCE CHARACTERISTICS
(Circuit from Figure 1, T
A
= 25°C, V
IN
= V
EN
= 12 V, V
OUT
= 3.3 V unless otherwise specified)
Figure 3. Light Load (DCM) Operation 1
ms/DIV
Figure 4. Full Load (CCM) Operation 1
ms/DIV
Figure 5. Start−Up into Full Load 1 ms/DIV
Figure 6. Short−Circuit Protection 200
ms
/DIV
Figure 7. 50% to 100% Load Transient 100
ms/DIV
Figure 8. 3.3 V Turn on into 1 V Pre−Bias 1 ms /DIV
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