NCV8925
3 MHz, 600 mA Step-Down
DC-DC Converter
High-Efficiency, Low Ripple, Adjustable
Output Voltage
The NCV8925 DC-DC buck converter is available in a space saving
low profile TSOP-5 and
mUDFN6
package. The part can supply output
voltages from 0.9 V to 3.3 V by an external resistor divider and is able
to deliver output currents up to 600 mA. This switching regulator
operates at 3.0 MHz and automatically switches between PFM and
PWM modes to improve system efficiency.
Soft-start, cycle-by-cycle current limiting and thermal shutdown
protection are also integrated in NCV8925.
The device is optimized for automotive applications and bring a high
frequency DC-DC solution for automotive requirements.
Features
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MARKING
DIAGRAMS
UDFN6
MU SUFFIX
CASE 517AB
1
2
3
ZEG
G
6
5
4
5
5
1
TSOP-5
SN SUFFIX
CASE 483
1
ZE,ACN= Specific Device Code
A
= Assembly Location
Y
= Year
W
= Work Week
G
= Pb-Free Package
(Note: Microdot may be in either location)
ACNAYWG
G
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Up to 93% Efficiency
Allow Use of Small External Components
Source up to 600 mA
3 MHz Switching Frequency
Adjustable Output Voltage from 0.9 V to 3.3 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
These are Pb-Free Devices
NCV Prefix for Automotive and Other Applications Requiring Site
and Control Changes
ORDERING INFORMATION
Device
NCV8925MUTBG
Package
Shipping
†
UDFN6 3000/T
ape & Reel
(Pb-Free)
TSOP-5 3000/T
ape & Reel
(Pb-Free)
NCV8925SNT1G
†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.
VIN
CIN
1
2
VIN
GND
EN
LX
5
L
COUT
VOUT
OFF ON
R1
1 EN
FB
6
L
Cff
2 GND LX
3 VIN GND
R2
VIN
CIN
5
4
R2
Cff
R1
VOUT
COUT
OFF ON
3
FB
4
Figure 1. Typical Application - TSOP-5
Figure 2. Typical Application - UDFN6
©
Semiconductor Components Industries, LLC, 2008
1
April, 2008 - Rev. 0
Publication Order Number:
NCV8925/D
NCV8925
Reference
Voltage
Logic Control
& Thermal
Shutdown
Enable
EN
1
FB
6
I
LIMIT
2.2
mH
GND
2
Q1
LX
5
4.7
mF
Vin
PWM/PFM
Control
Q2
GND
4
Vout
220 k
18 pF
VIN
3
220 k
4.7
mF
Figure 3. Simplified Block Diagram
PIN FUNCTION DESCRIPTION
Pin
TSOP-5
1
2
3
4
5
Pin
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 10
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.
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
(Top View)
6
5
4
FB
LX
GND
Figure 4. Pin Connections - TSOP-5
Figure 5. Pin Connections - UDFN6
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2
NCV8925
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 (Notes 6 and 7)
Storage Temperature Range
Junction Operating Temperature (Notes 6 and 7)
Latchup Current Maximum Rating (T
A
= 85°C) (Note 4) Other Pins
ESD Withstand Voltage (Note 3)
Human Body Model
Machine Model
Moisture Sensitivity Level (Note 5)
TSOP-5
UDFN6
T
A
T
stg
T
j
Lu
V
esd
2.0
200
MSL
1
kV
V
per IPC
Symbol
V
min
V
max
V
max
R
qJA
300
220
-40 to 125
-55 to 150
-40 to 150
$100
°C
°C
°C
mA
Value
-0.3
7.0
VIN + 0.3
Unit
V
V
V
°C/W
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.
6. In applications with high power dissipation (low V
IN
, high I
OUT
), special care must be paid to thermal dissipation issues. Board design
considerations - thermal dissipation vias, traces or planes and PCB material - can significantly improve junction to air thermal resistance R
qJA
(for more information, see design and layout consideration section). Environmental conditions such as ambient temperature Ta brings thermal
limitation on maximum power dissipation allowed.
The following formula gives calculation of maximum ambient temperature allowed by the application:
Ta
MAX
= Tj
MAX
- (R
qJA
x Pd)
Where Tj is the junction temperature,
Where
Pd is the maximum power dissipated by the device (worst case of the application),
Where
and R
qJA
is the junction-to-ambient thermal resistance.
7. To prevent permanent thermal damages, this device include a thermal shutdown which engages at 180°C (typ).
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3
NCV8925
ELECTRICAL CHARACTERISTICS
(Typical values are referenced to T
A
= +25°C, Min and Max values are referenced -40°C to
+125°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
Under Voltage 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 8)
Ambient Temperature
Overtemperature Range
Minimum Output Voltage (Note 9)
Maximum Output Voltage
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
DV
OUT
-
-3.0
V
OUT
V
OUT
V
OUT
-
V
OUT
-
-
V
OUT
-
V
OUT
-
V
OUT
V
OUT
I
LIM
F
OSC
-
T
START
T
SD
T
SDH
-
-
-
2.4
-
-
-
-
2.0
1.0
8.0
1200
3.0
-
320
160
25
-
-
-
-
3.6
100
500
-
-
mV
mV
mA
MHz
%
ms
°C
°C
0.08
-
mV
PP
50
54
-
-
%
0.0008
-
mV
-
-
$1.0
$2.0
0.9
3.3
%
-
$3.0
-
-
V
V
%/mA
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
-
50
0.2
2.4
5.5
90
1.5
2.55
V
mA
mA
V
TSOP
UDFN
Symbol
Min
Typ
Max
Unit
8. The overall output voltage tolerance depends upon the accuracy of the external resistor (R1, R2).
9. For V
OUT
= 0.9 V, maximum input voltage do not exceed 5.2 V.
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4
NCV8925
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
0.9
QUIESCENT CURRENT (mA)
0.8
STANDBY CURRENT (mA)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
V
IN
, INPUT VOLTAGE (V)
44
2.5
3.0
3.5
4.0
4.5
5.0
5.5
V
IN
, INPUT VOLTAGE (V)
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
56
54
52
50
48
46
Figure
6
7
8, 9
10, 11, 12
13
14
15
16, 17
18, 19
20, 21
22, 23, 25, 25
Figure 6. Shutdown Current vs. Supply Voltage
Figure 7. Quiescent Current PFM No Switching
vs. Supply Voltage
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