NCP1521B
1.5 MHz, 600 mA Step-Down
DC-DC Converter
High−Efficiency, Low Ripple, Adjustable
Output Voltage
The NCP1521B step−down DC−DC converter is a monolithic
integrated circuit optimized for portable applications powered from one
cell Li−Ion or three cell Alkaline/NiCd/NiMH batteries. The part,
available in adjustable output voltage versions ranging from 0.9 V to
3.9 V, is able to deliver up to 600 mA. It uses synchronous rectification
to increase efficiency and reduce external part count. The device also
has a built−in 1.5 MHz (nominal) oscillator which reduces component
size by allowing smaller inductors and capacitors. Automatic switching
PWM/PFM mode offers improved system efficiency.
Additional features include integrated soft−start, cycle−by−cycle
current limiting and thermal shutdown protection. The NCP1521B is
available in a space saving, low profile TSOP5 and UDFN6 packages.
Features
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MARKING
DIAGRAM
5
5
1
TSOP−5
SN SUFFIX
CASE 483
GALAYWG
G
1
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Up to 96% Efficiency
Best−In−Class Ripple, including PFM Mode
Sources up to 600 mA
1.5 MHz Switching Frequency
Adjustable Output Voltage from 0.9 V to 3.9 V
Synchronous Rectification for Higher Efficiency
2.7 V to 5.5 V Input Voltage Range
Low Quiescent Current
Shutdown Current Consumption of 0.3
mA
Thermal Limit Protection
Short Circuit Protection
All Pins are Fully ESD Protected
This is a Pb−Free Device
Cellular Phones, Smart Phones and PDAs
Digital Still/Video Cameras
MP3 Players and Portable Audio Systems
Wireless and DSL Modems
Portable Equipment
USB Powered Devices
VIN
CIN
2
GND
EN
FB
4
R2
1
VIN
LX
5
L
COUT
R1
Cff
VOUT
OFF ON
GAL
= Specific Device Code
A
= Assembly Location
Y
= Year
W
= Work Week
G
= Pb−Free Package
(Note: Microdot may be in either location)
UDFN6
MU SUFFIX
CASE 517AB
1
6
2 ZCMG 5
G
3
4
ZC
= Specific Device Code
M
= Date Code
G
= Pb−Free Package
(Note: Microdot may be in either location)
ORDERING INFORMATION
Device
NCP1521BSNT1G
NCP1521BMUTBG
Package
Shipping
†
Typical Applications
TSOP−5 3000/T
ape & Reel
(Pb−Free)
UDFN6 3000/T
ape & Reel
(Pb−Free)
†For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specification
Brochure, BRD8011/D.
R2
1 EN
FB
6
5
4
R1
VOUT
2 GND LX
3 VIN GND
OFF ON
3
Figure 1. Typical Application
−
TSOP−5
VIN
Figure 2. Typical Application
−
UDFN6
©
Semiconductor Components Industries, LLC, 2010
December, 2010
−
Rev. 5
1
Publication Order Number:
NCP1521B/D
NCP1521B
100%
95%
90%
EFFICIENCY (%)
85%
80%
75%
70%
65%
60%
55%
50%
0
100
200
300
400
500
V
OUT
= 3.3 V
V
IN
= 4.2 V
T
A
= 25°C
600
700
I
OUT
(mA)
Figure 3. Efficiency vs. Output Current
Q1
V
battery
Q2
VIN
1
PWM/PFM
CONTROL
LX
5
2.2
mH
10
mF
4.7
mF
GND
2
I
LIMIT
R1
18 pF
Enable
EN
3
LOGIC
CONTROL
& THERMAL
SHUTDOWN
REFERENCE
VOLTAGE
FB
4
R2
Figure 4. Simplified Block Diagram
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2
NCP1521B
PIN FUNCTION DESCRIPTION
Pin No.
TSOP5
1
2
3
4
5
Pin No.
UDFN6
3
2, 4
1
6
5
Pin Name
VIN
GND
EN
FB
LX
Type
Analog /
Power Input
Analog /
Power Ground
Digital Input
Analog Input
Analog Output
Description
Power supply input for the PFET power stage, analog and digital blocks. The
pin must be decoupled to ground by a 4.7
mF
ceramic capacitor.
This pin is the GND reference for the NFET power stage and the analog sec-
tion of the IC. The pin must be connected to the system ground.
Enable for switching regulators. This pin is active HIGH and is turned off by
logic LOW on this pin. Do not let this pin float.
Feedback voltage from the output of the power supply. This is the input to the
error amplifier.
Connection from power MOSFETs to the Inductor.
PIN CONNECTIONS
VIN
GND
EN
1
2
3
(Top View)
4
FB
5
LX
EN
GND
VIN
1
2
3
6
5
4
FB
LX
GND
Figure 5. Pin Connections
−
TSOP5
Figure 6. Pin Connections
−
UDFN6
MAXIMUM RATINGS
Rating
Minimum Voltage All Pins
Maximum Voltage All Pins (Note 2)
Maximum Voltage EN, FB, LX
Thermal Resistance, Junction
−to−Air
(with Recommended Soldering Footprint)
Operating Ambient Temperature Range
Storage Temperature Range
Junction Operating Temperature
Latch−up Current Maximum Rating (T
A
= 85°C) (Note 4)
ESD Withstand Voltage (Note 3)
Human Body Model
Machine Model
Moisture Sensitivity Level (Note 5)
TSOP5
UDFN6
Symbol
V
min
V
max
V
max
R
qJA
Value
−0.3
7.0
VIN + 0.3
300
260
−40
to 85
−55
to 150
−40
to 125
$100
2.0
200
1
Unit
V
V
V
°C/W
T
A
T
stg
T
j
Lu
V
esd
°C
°C
°C
mA
kV
V
per IPC
MSL
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.
1. Maximum electrical ratings are defined as those values beyond which damage to the device may occur at T
A
= 25°C.
2. According to JEDEC standard JESD22−A108B.
3. This device series contains ESD protection and exceeds the following tests:
Human Body Model (HBM) per JEDEC standard: JESD22−A114.
Machine Model (MM) per JEDEC standard: JESD22−A115.
4. Latchup current maximum rating per JEDEC standard: JESD78.
5. JEDEC Standard: J−STD−020A.
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3
NCP1521B
ELECTRICAL CHARACTERISTICS
(Typical values are referenced to T
A
= +25°C, Min and Max values are referenced
−40°C
to +85°C
ambient temperature, unless otherwise noted, operating conditions V
IN
= 3.6 V, V
OUT
= 1.2 V, unless otherwise noted.)
Pin
Rating
VIN PIN
Input Voltage Range
Quiescent Current, PFM No Switching
Standby Current, EN Low
Undervoltage Lockout (V
IN
Falling)
EN PIN
Positive going Input High Voltage Threshold, EN0 Signal
Negative going Input High Voltage Threshold, EN0 Signal
EN High Input Current, EN = 3.6 V
OUTPUT
Output Voltage Accuracy (Note 6)
Ambient Temperature
Overtemperature Range
Feedback Voltage Threshold
Minimum Output Voltage
Maximum Output Voltage
Maximum Output Voltage for USB or 5 V Rail Powered Applications
Vin from 4.3 V to 5.5 V (Note 7)
Output Voltage load regulation Overtemperature
I
OUT
= 100 mA to 600 mA
Load Transient Response, Rise/Falltime 1
ms
10 mA to 100 mA Load Step
200 mA to 600 mA Load Step
Output Voltage Line Regulation, I
OUT
= 100 mA,
V
IN
= 2.7 V to 5.5 V
Line Transient Response, I
OUT
= 100 mA,
3.6 V to 3.0 V Line Step (Falltime=50
ms)
Output Voltage Ripple, I
OUT
= 300 mA (PWM Mode)
Output Voltage Ripple, I
OUT
= 0 mA (PFM Mode)
Peak Inductor Current
Oscillator Frequency
Duty Cycle
Soft−Start Time
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
POWER SWITCHES
P−Channel On−Resistance
N−Channel On−Resistance
P−Channel Leakage Current
N−Channel Leakage Current
RLxH
RLxL
I
LeakH
I
LeakL
−
−
−
−
400
400
0.05
0.01
−
−
−
−
mW
mW
mA
mA
5
5
5
5
5
5
4
6
V
OUT
−
−3.0
−
−
−
−
−
−
−
−
−
−
−
−
−
1.3
−
−
−
−
$1.0
$2.0
0.6
0.9
3.3
3.9
0.0005
−
35
80
0.05
6
2.0
8.0
1200
1.5
−
320
160
25
−
3.0
−
−
−
−
−
−
−
−
−
−
−
−
−
1.8
100
500
−
−
%
3
3
3
1
1
1
V
IH
V
IL
I
ENH
1.2
−
−
−
−
2.0
−
0.4
−
V
V
mA
1
1
1
1
3
3
3
3
V
IN
I
q ON
I
q OFF
V
UVLO
2.7
−
−
2.2
−
30
0.2
2.4
5.5
45
1.5
2.55
V
mA
mA
V
TSOP UDFN
Symbol
Min
Typ
Max
Unit
V
FB
V
OUT
V
OUT
V
OUT
V
OUT
V
V
V
V
%/mA
V
OUT
mV
V
OUT
V
OUT
V
OUT
V
OUT
I
LIM
F
OSC
−
T
START
T
SD
T
SDH
%
mV
PP
mV
mV
mA
MHz
%
ms
°C
°C
6. The overall output voltage tolerance depends upon the accuracy of the external resistor (R1, R2).
7. Functionality guaranteed per design and characterization, see chapter ”USB or 5 V Rail Powered Applications”.
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4
NCP1521B
TABLE OF GRAPHS
Typical Characteristics for Step−down Converter
I
STB
I
q
V
OUT
Eff
Freq
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
1.0
0.9
0.8
0.7
I
STB
(mA)
0.6
0.5
0.4
0.3
0.2
0.1
0
2.7
3.2
3.7
4.2
4.7
5.2
EN = 0 V
QUIESCENT CURRENT (mA)
I
OUT
= 0 mA
34
33
32
31
30
29
2.5
Standby Current
Quiescent Current, PFM No Switching
Output Voltage Accuracy
Efficiency
Switching Frequency
Soft−Start
Short Circuit Protection
Line Regulation
Line Transient
Load Regulation
Load Transient
vs. Input Voltage
vs. Input Voltage
vs. Temperature
vs. Output Current
vs. Input Voltage
vs. Time
vs. Time
vs. Input Voltage
vs. Time
vs. Output Current
vs. Time
35
EN = V
IN
I
OUT
= 0 mA
Figure
7
8
9 and 10
11, 12, 13 and 29
14
15
16
17 and 18
19 and 20
21, 22 and 30
23, 24, 25 and 26
3.0
3.5
4.0
4.5
5.0
5.5
Figure 7. Shutdown Current vs. Supply Voltage
V
IN
, INPUT VOLTAGE (V)
Figure 8. Quiescent Current PFM No Switching
vs. Supply Voltage
V
IN
, INPUT VOLTAGE (V)
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