NCP1596, NCP1596A
Product Preview
1.5 A, 1.5 MHz Current
Mode PWM Buck Down
Converter
The NCP1596/NCP1596A is a current mode PWM buck converter
with integrated power switch. It can provide up to 1.5 A output current
with high conversion efficiency. High frequency PWM control
scheme can provide a low output ripple noise. Thus, it allows the
usage of small size passive components to reduce the board space. In a
low load condition, the controller will automatically change to PFM
mode which provides a higher efficiency at low load. Additionally, the
device includes soft−start, thermal shutdown with hysteresis,
cycle−by−cycle current limit, and short circuit protection. This device
is available in a compact 3x3 DFN package.
Features
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1
6 PIN DFN 3x3
MN SUFFIX
CASE 506AH
MARKING DIAGRAMS
1 N1596
ALYW
G
1 1596A
ALYW
G
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
High Efficiency up to 90%, 1 A @ 3.3 V, 75% @ 1.2 V
Fully Internal Compensation
Low Output Voltage Ripple, 20 mV Typical
±1.5%
Reference Voltage
High PWM Switching Frequency, 1.5 MHz
Automatic PWM / PFM Switchover at Light Load
Built−in 1 ms Digital Soft Start
Cycle−by−cycle Current Limit
Thermal Shutdown with Hysteresis
Internal UVLO Protection
Ext. Adjustable Output Voltage
Low Profile and Minimum External Components
Designed for use with Ceramic Capacitor
Compact 3x3 DFN Package
These are Pb−Free Devices
N1596/1596A = Specific Device Code
A
= Assembly Location
L
= Wafer Lot
Y
= Year
W = Work Week
G
= Pb−Free Package
PIN CONNECTIONS
FB
GND
LX
1596
(Top View)
NC
VCC
VCCP
FB
GND
LX
1596A
EN
VCC
VCCP
Typical Applications
•
Hard Disk Drives
•
USB Power Device
•
Wireless and DSL Modems
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 11 of this data sheet.
This document contains information on a product under development. ON Semiconductor
reserves the right to change or discontinue this product without notice.
©
Semiconductor Components Industries, LLC, 2009
March, 2009
−
Rev. P3
1
Publication Order Number:
NCP1596/D
NCP1596, NCP1596A
V
IN
= 4.0 V to 5.5 V
VCCP
NCP1596
VCC
C1
NC/EN
GND
FB
R2
LX
D1
R1
C2
L1
V
OUT
= 0.8 V to 0.9 x V
IN
Figure 1. Typical Operating Circuit
ABSOLUTE MAXIMUM RATINGS
Rating
Power Supply (Pins 4, 5)
Symbol
V
IN
Value
6.0
−0.3
(DC)
−1.0
(100 ns)
6.0
−0.3
(DC)
−1.0
(100 ns)
Unit
V
Input / Output Pins
Pins 1, 3, 6
Thermal Characteristics
3x3 DFN Plastic Package
Maximum Power Dissipation @ T
A
= 25°C
Thermal Resistance Junction−to−Air
Operating Junction Temperature Range (Note 4)
Operating Ambient Temperature Range
Storage Temperature Range
Lead Temperature Soldering (10 sec)
Moisture Sensitivity Level (Note 3)
V
IO
V
P
D
R
qJA
T
J
T
A
T
stg
1450
68.5
−40
to +150
−40
to +85
−55
to +150
230
1.0
mW
°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.
NOTE: ESD data available upon request.
1. This device series contains ESD protection and exceeds the following tests:
Human Body Model (HBM) 2.0 kV per JEDEC standard: JESD22−A114.
Machine Model (MM) 200 V per JEDEC standard: JESD22−A115.
2. Latch−up Current Maximum Rating: 150 mA per JEDEC standard: JESD78.
3. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J−STD−020A.
4. The maximum package power dissipation limit must not be exceeded.
P
D
+
T
J(max)
*
T
A
R
qJA
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2
NCP1596, NCP1596A
ELECTRICAL CHARACTERISTICS
(V
IN
= 5.0 V, V
OUT
= 1.2 V, T
A
= 25°C for typical value,
−40°C
≤
T
A
≤
85°C for min/max values unless otherwise noted)
Characteristic
Operating Voltage
Under Voltage Lockout Threshold
Under Voltage Lockout hysteresis
PFET Leakage Current (Pins 5, 4)
T
A
= 25°C
T
A
=
−40°C
to 85°C
FEEDBACK VOLTAGE
FB Input Threshold (T
A
=
−40°C
to 85°C)
FB Input Current
THERMAL SHUTDOWN
Thermal Shutdown Threshold (Note 5)
Hysteresis
PWM SMPS MODE
Switching Frequency (T
A
=
−40°C
to 85°C)
Internal PFET ON−Resitance (I
LX
= 100 mA, V
IN
= 5.0 V, T
A
= 25°C) (Note 5)
Minimum Duty Cycle
Maximum Duty Cycle
Soft−Start Time (V
IN
= 5.0 V, V
o
= 1.2 V, I
LOAD
= 0 mA, T
A
= 25°C)
Main PFET Switch Current Limit (Note 5)
ENABLE
−
NCP1596A
Enable Threshold High (NCP1596A Only)
Enable Threshold Low
Enable bias current (EN = 0 V)
EFFICIENCY
Output Load Current 10 mA @ 1.2 V (Note 5)
Output Load Current 100 mA to 1.2 A @ 1.2 V (Note 5)
TOTAL DEVICE
Quiescent Current Into V
CCP
(V
IN
= 5 V, V
FB
= 1.0 V, T
A
= 25°C)
Quiescent Current Into V
CC
(V
IN
= 5 V, V
FB
= 1.0 V, T
A
= 25°C)
Shutdown Quiescent Current into V
CC
and V
CCP
(NCP1596A Only)
(EN = 0, V
IN
= 5 V, V
FB
= 1.0 V, T
A
= 25°C)
5. Values are design guaranteed.
I
CCP
I
CC
I
CC_SD
−
−
−
10
500
1.0
−
−
3.0
mA
mA
mA
h
h
−
−
50
70
−
−
%
%
V
EN_H
V
EN_L
I
EN
1.8
−
−
−
−
500
−
0.4
TBD
V
V
nA
F
OSC
R
DS(on)_P
D
MIN
D
MAX
T
SS
I
LIM
1.27
−
−
−
0.8
2.0
1.5
0.2
0
100
1.0
2.5
1.725
0.3
−
−
1.2
−
MHz
Ohm
%
%
ms
A
T
SHDN
T
SDHYS
−
−
160
30
−
−
°C
°C
V
FB
I
FB
0.788
−
0.800
10
0.812
100
V
nA
Symbol
V
IN
V
UVLO
V
UVLO_HYS
I
LEAK−P
Min
4.0
3.2
−
−
−
Typ
−
3.5
180
1.0
−
Max
5.5
3.8
−
10
15
Unit
V
V
mV
mA
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3
NCP1596, NCP1596A
PIN FUNCTION DESCRIPTIONS
Pin #
NCP1596
1
2
3
4
5
6
NCP1596A
1
2
3
4
5
6
FB
GND
LX
VCCP
VCC
EN
Feedback pin. Part is internally compensated. Only necessary to place a voltage divider or connect the out-
put directly to this pin.
Ground
Pin connected internally to power switch. Connect externally to inductor.
Power connection to the power switch.
IC power connection.
Device Enable pin. This pin has an internal current source pull up. No connect is enable the device. With this
pin pulled down below 0.8 V, the device is disabled and enters the shutdown mode.
FB
GND
LX
VCCP
VCC
NC
Feedback pin. Part is internally compensated. Only necessary to place a voltage divider or connect the out-
put directly to this pin.
Ground
Pin connected internally to power switch. Connect externally to inductor.
Power connection to the power switch.
IC power connection.
No Connection
Symbol
Pin Description
NC/EN
500 nA
Vin
VCC
C1
UVLO
Thermal
Shutdown
Isense
FB
Short
circuit
protect
Soft Start
S
R
0.8 V
Q
driver
Q
Ton(min)
disable
Isense
Oscillator
VCCP
V
out
= 0.8 V to 0.9 V * V
in
LX
L1
R1
D1
GND
R2
C2
Figure 2. Detail Block Diagram
EXTERNAL COMPONENT REFERENCE DATA
Device
V
OUT
3.3 V
2.5 V
NCP1596/
NCP1596A
1.5 V
1.2 V
Inductor Model
CDC5D23 3R3 (1 A)
CDRH6D38 3R3 (1.5 A)
CDC5D23 3R3 (1 A)
CDRH6D38 3R3 (1.5 A)
CDC5D23 3R3 (1 A)
CDRH6D38 3R3 (1.5 A)
CDC5D23 3R3 (1 A)
CDRH6D38 3R3 (1.5 A)
Inductor (L1)
3.3
mH
3.3
mH
3.3
mH
3.3
mH
Diode (D1)
MBRA210LT3G
MBRA210LT3G
MBRA210LT3G
MBRA210LT3G
C
IN
(C1)
22
mF
22
mF
x 2
22
mF
22
mF
x 2
22
mF
22
mF
x 2
22
mF
22
mF
x 2
C
OUT
(C2)
22
mF
22
mF
x 2
22
mF
22
mF
x 2
22
mF
22
mF
x 2
22
mF
22
mF
x 2
R1
31 k
21 k
8k
5k
R2
10 k
10 k
10 k
10 k
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4
NCP1596, NCP1596A
3.8 V
VIN
TIME 1 ms/div
1 ms
3.5 V
VOUT
NC
EN
1.8 V
0.4 V
TIME 1 ms/div
Figure 3. Timing Diagram
Power up the
device
VCC > 3 V
Enable the
internal Vref
VCC > UVLO
NO
Disable the
Oscillator,
OTA and driver
YES
YES
Enable
Oscillator,
OTA and
driver
Temperature
<
130 deg
NO
Ramp up
Soft start
(1 ms)
YES
YES
VCC
<
UVLO
Normal
Operation
Current Limit
> 2.5 A
Temperature
>
160 deg
YES
Figure 4. State Diagram
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