NCP1587, NCP1587A
Low Voltage Synchronous
Buck Controller
The NCP1587 and NCP1587A are low cost PWM controllers
designed to operate from a 5 V or 12 V supply. These devices are
capable of producing an output voltage as low as 0.8 V. These 8−pin
devices provide an optimal level of integration to reduce size and cost
of the power supply. The NCP1587/A provide a 1 A gate driver design
and an internally set 275 kHz (NCP1587) and 200 kHz (NCP1587A)
oscillator. In addition to the 1 A gate drive capability, other efficiency
enhancing features of the gate driver include adaptive non−overlap
circuitry. The devices also incorporate an externally compensated
error amplifier and a capacitor programmable soft−start function.
Protection features include programmable short circuit protection and
under voltage lockout (UVLO). The NCP1587/A comes in an 8−pin
SOIC package.
Features
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MARKING DIAGRAM
8
8
1
SOIC−8
D SUFFIX
CASE 751
1
1587x = Specific Device Code
(x = A for NCP1587A,
blank for NCP1587)
A
= Assembly Location
L
= Wafer Lot
Y
= Year
W
= Work Week
G
= Pb−Free Device
1587x
ALYW
G
•
•
•
•
•
•
•
•
•
•
•
•
Input Voltage Range from 4.5 to 13.2 V
275 kHz (NCP1587) and 200 kHz (NCP1587A) Internal Oscillator
Boost Pin Operates to 30 V
Voltage Mode PWM Control
0.8 V
±1.0
% Internal Reference Voltage
Adjustable Output Voltage
Capacitor Programmable Soft−Start
Internal 1 A Gate Drivers
80% Max Duty Cycle
Input Under Voltage Lockout
Programmable Current Limit
These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
Graphics Cards
Desktop Computers
Servers / Networking
DSP & FPGA Power Supply
DC−DC Regulator Modules
PIN CONNECTIONS
BST 1
TG 2
GND 3
BG 4
(Top View)
8 PHASE
7 COMP/DIS
6 FB
5 V
CC
Applications
ORDERING INFORMATION
Device
NCP1587DR2G
NCP1587ADR2G
Package
SOIC−8
(Pb−Free)
SOIC−8
(Pb−Free)
Shipping
†
2500/Tape & Reel
2500/Tape & Reel
•
•
•
•
•
†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.
©
Semiconductor Components Industries, LLC, 2012
May, 2012
−
Rev. 5
1
Publication Order Number:
NCP1587/D
NCP1587, NCP1587A
12 V
3.3 V
V
CC
FB
COMP/DIS
BST
TG
PHASE
V
OUT
GND
BG
Figure 1. Typical Application Diagram
POR
UVLO
VOCTH
FAULT
FB
6
-
+
0.8 V
(V
REF
)
GM
+
-
R
S
PWM
OUT
Q
LATCH
SCP
+
-
5
V
CC
FAULT
1
2
8
BST
TG
PHASE
Clock
Ramp
COMP/DIS
7
OSC
OSC
+
-
2V
+
-
V
CC
4
FAULT
3
BG
R
set
GND
Figure 2. Detailed Block Diagram
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2
NCP1587, NCP1587A
PIN FUNCTION DESCRIPTION
Pin No.
1
Symbol
BST
Description
Supply rail for the floating top gate driver. To form a boost circuit, use an external diode to bring the
desired input voltage to this pin (cathode connected to BST pin). Connect a capacitor (C
BST
) between this pin
and the PHASE pin. Typical values for C
BST
range from 0.1
mF
to 1
mF.
Ensure that C
BST
is placed near the IC.
Top gate MOSFET driver pin. Connect this pin to the gate of the top N−Channel MOSFET.
IC ground reference. All control circuits are referenced to this pin.
Bottom gate MOSFET driver pin. Connect this pin to the gate of the bottom N−Channel MOSFET.
Supply rail for the internal circuitry. Operating supply range is 4.5 V to 13.2 V. Decouple with a 1
mF
capacitor to GND. Ensure that this decoupling capacitor is placed near the IC.
This pin is the inverting input to the error amplifier. Use this pin in conjunction with the COMP pin to
compensate the voltage−control feedback loop. Connect this pin to the output resistor divider (if used) or dir-
ectly to V
out
.
Compensation Pin. This is the output of the error amplifier (EA) and the non−inverting input of the PWM com-
parator. Use this pin in conjunction with the FB pin to compensate the voltage−control feedback loop. The com-
pensation capacitor also acts as a soft−start capacitor. Pull this pin low for disable.
Switch node pin. This is the reference for the floating top gate driver. Connect this pin to the source of the top
MOSFET.
2
3
4
5
6
TG
GND
BG
V
CC
FB
7
COMP/DIS
8
PHASE
ABSOLUTE MAXIMUM RATINGS
Pin Name
Main Supply Voltage Input
Bootstrap Supply Voltage Input
Symbol
V
CC
BST
V
MAX
15 V
35 V wrt/PGND
40 V < 50 ns wrt/PGND
15 V wrt/SW
35 V
40 V < 50 ns
30 V wrt/GND
15 V wrt/PHASE
15 V
5.5 V
5.5 V
V
MIN
−0.3
V
−0.3
V
−0.3
V
−0.3
V
−5.0
V
−10
V for < 200 ns
−0.3
V wrt/PHASE
−2
V < 200 ns wrt/PHASE
−0.3
V
−5.0
V for < 200 ns
−0.3
V
−0.3
V
Switching Node (Bootstrap Supply Return)
High−Side Driver Output (Top Gate)
Low−Side Driver Output (Bottom Gate)
Feedback
COMP/DISABLE
PHASE
TG
BG
FB
COMP/DIS
MAXIMUM RATINGS
Rating
Thermal Resistance, Junction−to−Ambient
Thermal Resistance, Junction−to−Case
NCP1587A Operating Junction Temperature Range
NCP1587A Operating Ambient Temperature Range
Storage Temperature Range
Lead Temperature Soldering (10 sec): Reflow (SMD styles only) Pb−Free
Symbol
R
qJA
R
qJC
T
J
T
A
T
stg
Value
165
45
0 to 125
0 to 70
−55
to +150
260
Unit
°C/W
°C/W
°C
°C
°C
°C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
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3
NCP1587, NCP1587A
ELECTRICAL CHARACTERISTICS
(0_C < T
A
< 70_C; 4.5 V < V
CC
< 13.2 V, 4.5 V < [BST−PHASE] < 13.2 V, 4.5 V < BST < 30 V,
0 V < PHASE < 21 V, C
TG
= C
BG
= 1.0 nF, for min/max values unless otherwise noted.)
Characteristic
Input Voltage Range
Boost Voltage Range
Supply Current
Quiescent Supply Current
Boost Quiescent Current
Under Voltage Lockout
UVLO Threshold
UVLO Hysteresis
Switching Regulator
VFB Feedback Voltage,
Control Loop in Regulation
Oscillator Frequency
Ramp−Amplitude Voltage
Minimum Duty Cycle
Maximum Duty Cycle
Error Amplifier (GM)
Transconductance
Open Loop DC Gain
Output Source Current
Output Sink Current
Input Bias Current
Soft−Start
SS Source Current
Switch Over Threshold
Gate Drivers
Upper Gate Source
Upper Gate Sink
Lower Gate Source
Lower Gate Sink
TG Falling to BG Rising Delay
BG Falling to TG Rising Delay
Enable Threshold
Over−Current Protection
OCSET Current Source
OC Switch−Over Threshold
Fixed OC Threshold
Sourced from BG pin, before SS
9.89
−
−
10
700
−375
11.1
−
−
mA
mV
mV
V
CC
= 12 V, TG < 2.0 V, BG > 2.0 V
V
CC
= 12 V, BG < 2.0 V, TG > 2.0 V
V
CC
= 12 V, VTG = VBG = 2.0 V
−
−
−
−
−
−
0.3
1.0
1.0
1.0
2.0
40
35
0.4
−
−
−
−
90
90
0.5
A
A
A
A
ns
ns
V
V
FB
< 0.8 V
V
FB
= 0.8 V
8.49
−
11
100
13.3
−
mA
% of Vref
V
FB
< 0.8 V
V
FB
> 0.8 V
3.0
55
80
80
−
−
70
120
120
0.1
4.4
−
−
−
1.0
mmho
DB
mA
mA
NCP1587
NCP1587A
T
A
= 0 to 70°C
T
A
= 0 to 70°C
792
250
180
0.8
0
70
800
275
200
1.1
−
75
808
300
220
1.4
−
80
mV
kHz
V
%
%
V
CC
Rising Edge
−
3.8
−
−
350
4.2
−
V
mV
V
FB
= 1.0 V, No Switching, V
CC
= 13.2 V
V
FB
= 1.0 V, No Switching, V
CC
= 13.2 V
1.0
0.1
−
−
8.0
1.0
mA
mA
Conditions
−
−
Min
4.5
4.5
Typ
−
−
Max
13.2
26.5
Unit
V
V
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4
NCP1587, NCP1587A
TYPICAL CHARACTERISTICS
(T
A
= 25°C unless otherwise noted)
5.0
4.7
4.4
4.1
3.8
3.5
203
202
201
200
199
198
V
CC
= 12 V
F
SW
, FREQUENCY (Khz)
I
CC
(mA)
V
CC
= 5 V
0
10
20
30
40
50
60
70
0
10
20
30
40
50
60
70
T
J
, JUNCTION TEMPERATURE (°C)
T
J
, JUNCTION TEMPERATURE (°C)
Figure 3. I
CC
vs. Temperature
SOFT START SOURCING CURRENT (mA)
14
13
12
11
10
9
8
375
365
355
345
335
325
Figure 4. Oscillator Frequency (F
SW
) vs.
Temperature
0
10
20
30
40
50
60
70
SCP THRESHOLD (mV)
0
10
20
30
40
50
60
70
T
J
, JUNCTION TEMPERATURE (°C)
T
J
, JUNCTION TEMPERATURE (°C)
Figure 5. Soft Start Sourcing Current vs.
Temperature
808
806
V
ref
, REFERENCE (mV)
804
802
800
798
796
794
792
0
10
20
30
40
Figure 6. SCP Threshold vs. Temperature
50
60
70
T
J
, JUNCTION TEMPERATURE (°C)
Figure 7. Reference Voltage (V
ref
) vs.
Temperature
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