NCV890101 [ONSEMI]
1.2A, 2MHz Automotive Buck Switching Regulator; 1.2A ， 2MHz的汽车降压型开关稳压器
| 型号： | NCV890101 |
| 厂家： | 
ONSEMI |
| 描述： | 1.2A, 2MHz Automotive Buck Switching Regulator |
| 文件： | 总15页 (文件大小：182K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
NCV890101
1.2A, 2MHz Automotive
Buck Switching Regulator
The NCV890101 is a fixed−frequency, monolithic, Buck switching
regulator intended for Automotive, battery−connected applications
that must operate with up to a 36V input supply. The regulator is
suitable for systems with low noise and small form factor
requirements often encountered in automotive driver information
systems. The NCV890101 is capable of converting the typical 4.5 V to
18 V automotive input voltage range to outputs as low as 3.3 V at a
constant switching frequency above the sensitive AM band,
eliminating the need for costly filters and EMI countermeasures. Two
pins are provided to synchronize switching to a clock, or to another
NCV890101. The NCV890101 also provides several protection
features expected in Automotive power supply systems such as current
limit, short circuit protection, and thermal shutdown. In addition, the
high switching frequency produces low output voltage ripple even
when using small inductor values and an all−ceramic output filter
capacitor − forming a space−efficient switching regulator solution.
http://onsemi.com
MARKING DIAGRAM
V8901
01
ALYWG
DFN10
G
CASE 485C
A
L
Y
W
G
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Device
(*Note: Microdot may be in either location)
Features
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 14 of this data sheet.
• Internal N−Channel Power Switch
• Low V Operation Down to 4.5 V
IN
• High V Operation to 36 V
IN
• Withstands Load Dump to 40 V
• 2 MHz Free−running Switching Frequency
• Low Shutdown Current
• Wettable Flanks − DFN
• NCV Prefix for Automotive and Other Applications
Requiring Unique Site and Control Change
Requirements; AEC−Q100 Qualified and PPAP
Capable
• Auto−synchronizes with Other NCV890101 or to an
External Clock
• Logic level Enable Input Can be Directly Tied to
Battery
• 1.4 A (min) Cycle−by−Cycle Peak Current Limit
• These Devices are Pb−Free and are RoHS Compliant
• Short Circuit Protection enhanced by Frequency
Foldback
Applications
• Audio
•
1.75% Output Voltage Tolerance
• Infotainment
• Safety − Vision Systems
• Instrumentation
• Output Voltage Adjustable Down to 0.8 V
• 1.4 Millisecond Internal Soft−Start
• Thermal Shutdown (TSD)
CDRV
DBST
NCV890101
VIN
L1
VOUT
COUT
1
2
3
4
5
VIN
SW 10
CBST
CIN
SYNC
DFW
DRV
BST
9
8
7
6
SYNC IN
OUT
RFB1
SYNCO SYNCI
GND
EN
FB
EN
RFB2
COMP
RCOMP
CCOMP
Figure 1. Typical Application
© Semiconductor Components Industries, LLC, 2013
1
Publication Order Number:
February, 2013 − Rev. 1
NCV890101/D
NCV890101
CDRV
SW
DBST
VIN
CIN
VIN
L1
VOUT
COUT
3.3 V
Reg
CBST
DFW
DRV
BST
Oscillator
Sync
PWM
LOGIC
ON
OFF
Sync Out
SYNCO
Sync In
SYNCI
Out
In
+
S
+
+
−
FB
GND
−
+
1.2 A
+
TSD
Soft−Start
RESET
COMP
VOLTAGES
MONITORS
RCOMP
EN
Enable
CCOMP
Figure 2. NCV890101 Block Diagram
http://onsemi.com
2
NCV890101
MAXIMUM RATINGS
Rating
Symbol
Value
−0.3 to 40
40
Unit
V
Min/Max Voltage VIN
Max Voltage VIN to SW
Min/Max Voltage SW
V
−0.7 to 40
−3.0
V
Min Voltage SW − 20ns
Min/Max Voltage BST
Min/Max Voltage BST to SW
Min/Max Voltage on EN
Min/Max Voltage COMP
Min/Max Voltage FB
V
−0.3 to 40
−0.3 to 3.6
−0.3 to 40
−0.3 to 2
−0.3 to 18
−0.3 to 3.6
−0.3 to 3.6
−0.3 to 6
50
V
V
V
V
Min/Max Voltage SYNCO
Min/Max Voltage DRV
Min/Max Voltage SYNCI
V
V
V
Thermal Resistance, 3x3 DFN Junction−to−Ambient*
Storage Temperature range
R
°C/W
°C
°C
q
JA
−55 to +150
−40 to +150
Operating Junction Temperature Range
T
J
ESD withstand Voltage
Human Body Model
V
ESD
2.0
200
>1.0
kV
V
kV
Machine Model
Charge Device Model
Moisture Sensitivity
MSL
Level 1
260
Peak Reflow Soldering Temperature
°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.
*Mounted on 1 sq. in. of a 4−layer PCB with 1 oz. copper thickness.
RECOMMENDED OPERATING CONDITIONS:
Rating
Value
Unit
V
V
IN
Range
4.5 to 36
−40 to 105
Ambient Temperature Range
°C
http://onsemi.com
3
NCV890101
SW
1
2
3
4
5
VIN
DRV
10
9
BST
8
SYNCI
FB
SYNCO
GND
7
COMP
EN
6
(Top View)
Figure 3. Pin Connections
PIN FUNCTION DESCRIPTIONS
Pin No.
Symbol
VIN
Description
1
2
3
Input voltage from battery. Place an input filter capacitor in close proximity to this pin.
Output voltage to provide a regulated voltage to the Power Switch gate driver.
DRV
SYNCO
Synchronization output. Turn−on of the Power Switch causes the SYNCO signal to fall. SYNCO rises
half a switching period later. Connecting to the SYNCI pin of another NCV890101 causes them to switch
out−of−phase
4
5
GND
EN
Battery return, and output voltage ground reference.
This TTL compatible Enable input allows the direct connection of Battery as the enable signal. Grounding
this input stops switching and reduces quiescent current draw to a minimum.
6
7
8
COMP
FB
Error Amplifier output, for tailoring transient response with external compensation components.
Feedback input pin to program output voltage, and detect pre−charged or shorted output conditions.
SYNCI
Synchronization input. Connecting an external clock to the SYNCI pin synchronizes switching to the
rising edge of the SYNCI voltage.
9
BST
SW
Bootstrap input provides drive voltage higher than VIN to the N−channel Power Switch for optimum
switch R
and highest efficiency.
DS(on)
10
Switching node of the Regulator. Connect the output inductor and cathode of the freewheeling diode to
this pin.
Exposed
Pad
Connect to Pin 4 (electrical ground) and to a low thermal resistance path to the ambient temperature
environment.
http://onsemi.com
4
NCV890101
ELECTRICAL CHARACTERISTICS (V = 4.5 V to 28 V, V = 5 V, V
= V
+ 3.0 V, C
= 0.1 mF, Min/Max values are valid
IN
EN
BST
SW
DRV
for the temperature range −40°C ≤ T ≤ 150°C unless noted otherwise, and are guaranteed by test, design or statistical correlation.)
J
Parameter
QUIESCENT CURRENT
Symbol
Conditions
Min
Typ
Max
Unit
Quiescent Current, shutdown
Quiescent Current, enabled
UNDERVOLTAGE LOCKOUT − VIN (UVLO)
UVLO Start Threshold
UVLO Stop Threshold
UVLO Hysteresis
I
I
V
IN
= 13.2 V, V = 0 V, T = 25°C
5
3
mA
qSD
EN
J
V
IN
= 13.2 V
mA
qEN
V
V
V
rising
falling
4.1
3.9
0.1
4.5
4.4
0.2
V
V
V
UVLSTT
UVLSTP
UVLOHY
IN
V
IN
V
ENABLE (EN)
Logic Low
V
0.8
8
V
V
ENLO
Logic High
V
2
ENHI
Input Current
I
30
mA
EN
SOFT−START (SS)
Soft−Start Completion Time
VOLTAGE REFERENCE
FB Pin Voltage during regulation
ERROR AMPLIFIER
FB Bias Current
t
0.8
1.4
0.8
2.0
0.814
1
ms
V
SS
V
FBR
COMP shorted to FB
0.786
0.25
I
V
FB
= 0.8 V
mA
FBBIAS
Transconductance
V
= 1.3 V
IN
IN
mmho
COMP
g
4.5 V < V < 18 V
0.6
0.3
1
0.5
1.5
0.75
m
g
20 V < V < 28 V
m(HV)
Output Resistance
R
1.4
MW
mA
OUT
SOURCE
COMP Source Current Limit
I
V
FB
= 0.63 V, V
= 1.3 V
COMP
4.5 V < V < 18 V
75
40
IN
20 V < V < 28 V
IN
COMP Sink Current Limit
I
V
FB
= 0.97 V, V
= 1.3 V
mA
SINK
COMP
4.5 V < V < 18 V
75
40
IN
20 V < V < 28 V
IN
Minimum COMP voltage
OSCILLATOR
V
F
V
= 0.97 V
0.2
0.7
V
CMPMIN
FB
Frequency
F
4.5 < V < 18 V
20 V < V < 28 V
1.8
0.9
2.0
1.0
2.2
1.1
MHz
SW
SW(HV)
IN
IN
VIN FREQUENCY FOLDBACK MONITOR
Frequency Foldback Threshold
V
FB
= 0.63 V
V
V
V
IN
V
IN
rising
falling
V
18.4
18
20
FLDUP
FLDDN
V
19.8
Frequency Foldback Hysteresis
V
FLDHY
0.2
0.3
0.4
1. Not tested in production. Limits are guaranteed by design.
http://onsemi.com
5
NCV890101
ELECTRICAL CHARACTERISTICS (V = 4.5 V to 28 V, V = 5 V, V
= V
+ 3.0 V, C
= 0.1 mF, Min/Max values are valid
IN
EN
BST
SW
DRV
for the temperature range −40°C ≤ T ≤ 150°C unless noted otherwise, and are guaranteed by test, design or statistical correlation.)
J
Parameter
SYNCHRONIZATION
Symbol
Conditions
Min
Typ
Max
Unit
SYNCO Output Pulse Duty Ratio
SYNCO Output Pulse Falltime
SYNCO Output Pulse Risetime
SYNCI Input Resistance to ground
SYNCI Input High Threshold Voltage
SYNCI Input Low Threshold Voltage
SYNCI High Pulse Width
D
C
= 40 pF
LOAD
40
60
%
ns
ns
k
(SYNC)
t
C
C
= 40 pF, 90% to 10%
= 40 pF, 10% to 90%
4
4
R(SYNC)
LOAD
LOAD
t
F(SYNC)
R
V
SYNCI
= 5.0 V
50
200
2.0
H(SYNC)
V
V
HSYNC
V
0.8
40
V
LSYNC
t
V
> max V
ns
ns
MHz
ns
HSYNCI
SYNC
HSYNC
SYNCI Low Pulse Width
t
V
< min V
40
LSYNCI
SYNC
LSYNC
External Sync Frequency
F
1.8
2.5
SYNCI
Master Reassertion Time
t
Time from last rising SYNCI edge
to first un−synchronized turn−on.
650
I(SYNC)
SLOPE COMPENSATION
Ramp Slope (Note 1)
(With respect to switch current)
S
4.5 < V < 18 V
0.7
0.25
1.3
0.6
A/ms
ramp
IN
S
20 V < V < 28 V
ramp(HV)
IN
POWER SWITCH
ON Resistance
R
V
= V + 3.0 V
SW
650
10
mW
mA
ns
DSON
BST
Leakage current VIN to SW
Minimum ON Time
Minimum OFF Time
I
V
= 0 V, V
= 0, V = 18 V
SW IN
LKSW
EN
t
Measured at SW pin
45
70
ONMIN
t
Measured at SW pin
ns
OFFMIN
At F
= 2 MHz (normal)
30
50
SW
At F
= 500 kHz (max duty cycle)
30
70
SW
PEAK CURRENT LIMIT
Current Limit Threshold
I
1.4
1.55
1.7
A
LIM
SHORT CIRCUIT FREQUENCY FOLDBACK
Lowest Foldback Frequency
F
V
= 0 V, 4.5 V < V < 18 V
400
200
24
500
250
32
600
300
40
kHz
SWAF
FB
IN
Lowest Foldback Frequency − High V
F
V
= 0 V, 20 V < V < 28 V
in
SWAFHV
FB IN
Hiccup Mode
F
V
FB
= 0 V
SWHIC
GATE VOLTAGE SUPPLY (DRV pin)
Output Voltage
V
3.1
2.7
2.5
16
3.3
2.9
2.8
3.5
3.05
3.0
45
V
V
DRV
DRV POR Start Threshold
DRV POR Stop Threshold
DRV Current Limit
V
V
DRVSTT
DRVSTP
DRVLIM
V
I
V
DRV
= 0 V
mA
OUTPUT PRECHARGE DETECTOR
Threshold Voltage
V
SSEN
20
35
50
mV
THERMAL SHUTDOWN
Activation Temperature (Note 1)
Hysteresis (Note 1)
T
150
5
190
20
°C
°C
SD
T
HYS
1. Not tested in production. Limits are guaranteed by design.
http://onsemi.com
6
NCV890101
TYPICAL CHARACTERISTICS CURVES
8
7
6
5
4
3
2
1
2.6
V
= 13.2 V
IN
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0
−50 −25
0
25
50
75
100
125
150
−50 −25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 4. Shutdown Quiescent Current vs.
Junction Temperature
Figure 5. Enabled Quiescent Current vs.
Junction Temperature
4.7
4.6
4.5
4.4
4.3
4.2
4.1
4.0
3.9
4.6
4.5
4.4
4.3
4.2
4.1
4.0
3.9
3.8
3.7
−50 −25
0
25
50
75
100
125
150
−50
−25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 6. UVLO Start Threshold vs. Junction
Temperature
Figure 7. UVLO Stop Threshold vs. Junction
Temperature
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.85
0.84
0.83
0.82
0.81
0.80
0.79
0.78
0.77
0.76
0.75
−50 −25
0
25
50
75
100
125
150
−50 −25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 8. Soft−Start Duration vs. Junction
Figure 9. FB Regulation Voltage vs. Junction
Temperature
Temperature
http://onsemi.com
7
NCV890101
TYPICAL CHARACTERISTICS CURVES
1.4
1.2
1.0
0.8
0.6
0.4
0.2
100
90
V
IN
= 4.5 V
80
V
= 4.5 V
IN
70
60
50
40
30
20
V
IN
= 28 V
V
IN
= 28 V
−50 −25
0
25
50
75
100
125
150
−50
−25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 10. Error Amplifier Transconductance
vs. Junction Temperature
Figure 11. Error Amplifier Max Sourcing
Current vs. Junction Temperature
100
90
80
70
60
50
40
30
20
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
V
= 13.2 V
IN
V
= 4.5 V
IN
V
= 28 V
IN
V
= 28 V
IN
−50
−25
0
25
50
75
100
125
150
−50
−25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 12. Error Amplifier Max Sinking Current
vs. Junction Temperature
Figure 13. Oscillator Frequency vs. Junction
Temperature
19.6
19.4
19.2
19.0
18.8
18.6
18.4
18.2
56
55
54
53
52
51
50
49
48
V
V
FLDUP
FLDDN
−50 −25
0
25
50
75
100
125
150
−50
−25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 14. Rising Frequency Foldback
Threshold vs. Junction Temperature
Figure 15. SYNCO Pulse Duty Ratio vs.
Junction Temperature
http://onsemi.com
8
NCV890101
TYPICAL CHARACTERISTICS CURVES
160
140
120
100
80
900
800
700
600
500
400
300
200
100
0
60
40
−50
−25
0
25
50
75
100
125
150
150
150
−50
−25
0
25
50
75
100
125
15
T . JUNCTION TEMPERATURE (°C)
T . JUNCTION TEMPERATURE (°C)
J
J
Figure 16. SYNCI Input Resistance vs.
Junction Temperature
Figure 17. Power Switch RDS(on) vs. Junction
Temperature
80
75
70
65
60
55
50
45
75
70
65
60
55
50
45
40
35
−50
40
−50
−25
0
25
50
75
100
125
−25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 18. Minimum On Time vs. Junction
Temperature
Figure 19. Minimum Off Time vs. Junction
Temperature
1.70
600
V
= 4.5 V
IN
550
500
450
400
350
300
250
200
1.65
1.60
1.55
1.50
1.45
1.40
V
= 28 V
IN
−50
−25
0
25
50
75
100
125
−50
−25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 20. Current Limit Threshold vs.
Junction Temperature
Figure 21. Short−Circuit Foldback Frequency
vs. Junction Temperature
http://onsemi.com
9
NCV890101
TYPICAL CHARACTERISTICS CURVES
40
38
36
34
32
30
28
26
24
3.50
3.45
3.40
3.35
3.30
3.25
3.20
3.15
3.10
I
= 0 mA
DRV
I
= 16 mA
DRV
−50
−25
0
25
50
75
100
125
150
−50
−25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 22. Hiccup Mode Switching Frequency
vs. Junction Temperature
Figure 23. DRV Voltage vs. Junction
Temperature
3.1
3.0
2.9
2.8
2.7
2.6
2.5
30
29
28
27
26
25
24
23
22
21
V
V
DRVSTT
DRVSTP
−50
−25
0
25
50
75
100
125
150
−50
−25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
T . JUNCTION TEMPERATURE (°C)
J
Figure 24. DRV Reset Threshold vs. Junction
Temperature
Figure 25. DRV Current Limit vs. Junction
Temperature
55
50
45
40
35
30
25
20
−50 −25
0
25
50
75
100
125
150
T . JUNCTION TEMPERATURE (°C)
J
Figure 26. Output Precharge Detector
Threshold vs. Junction Temperature
http://onsemi.com
10
NCV890101
GENERAL INFORMATION
INPUT VOLTAGE
inductor current at which the power switch shuts off. The
Current Mode control method employed by the NCV890101
allows the use of a simple, Type II compensation to optimize
the dynamic response according to system requirements.
An Undervoltage Lockout (UVLO) circuit monitors the
input, and inhibits switching and resets the Soft−start circuit
if there is insufficient voltage for proper regulation. The
NCV890101 can regulate a 3.3 V output with input voltages
above 4.5 V and a 5.0 V output with an input above 6.5 V.
The NCV890101 withstands input voltages up to 40 V.
To limit the power lost in generating the drive voltage for
the Power Switch, the switching frequency is reduced by a
factor of 2 when the input voltage exceeds the V
Frequency Foldback threshold V
Frequency reduction is automatically terminated when the
input voltage drops back below the V Frequency Foldback
SLOPE COMPENSATION
A fixed slope compensation signal is generated internally
and added to the sensed current to avoid increased output
voltage ripple due to bifurcation of inductor ripple current
at duty cycles above 50%. The fixed amplitude of the slope
compensation signal requires the inductor to be greater than
a minimum value, depending on output voltage, in order to
avoid sub−harmonic oscillations. For 3.3 V and 5 V output
voltages, the recommended inductor value is 4.7 mH.
IN
(see Figure 27).
FLDUP
IN
threshold V
.
FLDDN
SHORT CIRCUIT FREQUENCY FOLDBACK
Fsw
(MHz)
During severe output overloads or short circuits, the
NCV890101 automatically reduces its switching frequency.
This creates duty cycles small enough to limit the peak
current in the power components, while maintaining the
ability to automatically reestablish the output voltage if the
overload is removed. If the current is still too high after the
switching frequency folds back to 500 kHz, the regulator
enters an auto−recovery burst mode that further reduces the
dissipated power.
2
1
CURRENT LIMITING
Due to the ripple on the inductor current, the average
output current of a buck converter is lower than the peak
current setpoint of the regulator. Figure 28 shows − for a
4.7 mH inductor − how the variation of inductor peak current
with input voltage affects the maximum DC current the
NCV890101 can deliver to a load.
4
18 20
36
VIN (V)
Figure 27. NCV890101 Switching Frequency
Reduction at High Input Voltage
1.4
1.3
ENABLE
The NCV890101 is designed to accept either a logic level
signal or battery voltage as an Enable signal. EN low induces
a ’sleep mode’ which shuts off the regulator and minimizes
(3.3 V
)
OUT
1.2
1.1
1.0
0.9
0.8
0.7
0.6
its supply current to a couple of mA typically (I ) by
qSD
disabling all functions. Upon enabling, voltage is
established at the DRV pin, followed by a soft−start of the
switching regulator output.
(5 V
)
OUT
SOFT−START
Upon being enabled or released from a fault condition,
and after the DRV voltage is established, a soft−start circuit
ramps the switching regulator error amplifier reference
voltage to the final value. During soft−start, the average
switching frequency is lower than its normal mode value
(typically 2 MHz) until the output voltage approaches
regulation.
0
5
10
15
20
25
30
35
40
INPUT VOLTAGE (V)
Figure 28. NCV890101 Load Current Capability
with 4.7 mH Inductor
ERROR AMPLIFIER
The error amplifier is a transconductance type amplifier.
The output voltage of the error amplifier controls the peak
http://onsemi.com
11
NCV890101
SYNCHRONIZATION
does not arrive at the SYNCI pin within the Master
Reassertion Time, the NCV890101 controls its own
switching frequency, allowing uninterrupted operation in
the event that the clock (or controlling NCV890101) is
turned off.
If internal conditions or excessive input voltage cause an
NCV890101 to fold back its switching frequency, the main
oscillator switching frequency is still derived from the
frequency received at the SYNCI pin. Under these
conditions, the SYNCO pin is held low.
Two NCV890101 can be synchronized out−of−phase to
one another by connecting the SYNCO pin of one to the
SYNCI pin of the other (Figure 29). Any number of
NCV890101 can also be synchronized to an external clock
(Figure 30). If a part does not have its switching frequency
controlled by the SYNCI input, it drives the SYNCO pin low
when it turns on the power switch, and drives it high half a
switching period later. When the switching frequency is
controlled by the SYNCI input, the SYNCO pin is held low.
Synchronization starts within 2 ms of soft−start completion.
A rising edge at the SYNCI pin causes an NCV890101 to
immediately turn on the power switch. If another rising edge
An external pulldown resistor is not required at the
SYNCI pin if it is unconnected.
VIN
CDRV1
DBST1
NCV890101
CDRV2
VOUT1
COUT1
L1
DBST2
NCV890101
1 VIN
SW 10
CBS1T
CIN1
VOUT2
L2
DFW2
1
2
3
4
5
VIN
SW 10
2 DRV
3 SYNCO
4 GND
5 EN
BST
SYNCI
FB
9
8
7
6
DFW1
CBST2
CIN2
COUT2
RFB1
DRV
SYNCO
GND
EN
BST
SYNCI
FB
9
8
7
6
RFB1
Synchronization
COMP
RFB2
RCOMP1
EN2
COMP
RFB2
SYNC MASTER
CCOMP1
RCOMP2
CCOMP2
SYNC SLAVE
Figure 29. NCV890101s Synchronized to Each Other
Master Enabled by Battery
VIN
CDRV1
DBST1
NCV890101
CDR2V
VOUT1
COUT1
L1
DBST2
1 VIN
SW 10
CBS1T
NCV890101
VIN SW 10
CIN1
VOUT2
COUT2
L2
DFW1
1
2 DRV
3 SYNCO
4 GND
5 EN
BST 9
SYNCI 8
FB 7
CBST2
CIN2
RFB11
2
3
4
5
DRV
BST
SYNCI
FB
9
8
7
6
RFB21
DFW2
SYNCO
GND
EN
COMP
6
RFB12
RCOMP1
EN2
COMP
RFB22
RCOMP2
CCOMP1
Synchronization
CLK
CCOMP2
Figure 30. Both NCV890101s Synchronized to External Clock
#1 Enabled by Battery
http://onsemi.com
12
NCV890101
BOOTSTRAP
DESIGN METHODOLOGY
At the DRV pin an internal regulator provides a
ground−referenced voltage to an external capacitor (C ),
to allow fast recharge of the external bootstrap capacitor
The NCV890101 being a fixed−frequency regulator with
the switching element integrated, is optimized for one value
of inductor. This value is set to 4.7 mH, and the slope
compensation is adjusted for this inductor. The only
components left to be designed are the input and output
capacitor and the freewheeling diode.
DRV
(C ) used to supply power to the power switch gate driver.
BST
If the voltage at the DRV pin goes below the DRV UVLO
Threshold V , switching is inhibited and the
DRVSTP
Soft−start circuit is reset, until the DRV pin voltage goes
back up above V
Output capacitor:
The minimum output capacitor value can be calculated
based on the specification for output voltage ripple:
.
DRVSTT
In order for the bootstrap capacitor to stay charged, the
Switch node needs to be pulled down to ground regularly. In
very light load condition, the NCV890101 skips switching
cycles to ensure the output voltage stays regulated. When the
skip cycle repetition frequency gets too low, the bootstrap
voltage collapses and the regulator stops switching.
Practically, this means that the NCV890101 needs a
minimum load to operate correctly: to cover all conditions
of input voltage and temperature, this minimum load is 8
mA.
DIL
(eq. 1)
COUTmin
+
8 @ DVOUT @ FSW
With
− DI the inductor ripple current:
L
V
OUT
@ ǒ1 *
L @ FSW
Ǔ
VOUT
V
IN
(eq. 2)
DIL +
OUTPUT PRECHARGE DETECTION
Prior to Soft−start, the FB pin is monitored to ensure the
SW voltage is low enough to have charged the external
− DV
the desired voltage ripple.
OUT
However, the ESR of the output capacitor also contributes
to the output voltage ripple, so to comply with the
requirement, the ESR cannot exceed R
bootstrap capacitor (C ). If the FB pin is higher than
BST
:
ESRmax
V
SSEN
, restart is delayed until the output has discharged.
DVOUT @ L @ FSW
RESRmax
+
THERMAL SHUTDOWN
(eq. 3)
V
OUT
A thermal shutdown circuit inhibits switching, resets the
Soft−start circuit, and removes DRV voltage if internal
temperature exceeds a safe level. Switching is automatically
restored when temperature returns to a safe level.
ǒ1 *
Ǔ
VOUT
V
IN
Finally, the output capacitor must be able to sustain the ac
current (or RMS ripple current):
DIL
MINIMUM DROPOUT VOLTAGE
(eq. 4)
IOUTac
+
Ǹ
When operating at low input voltages, two parameters
play a major role in imposing a minimum voltage drop
across the regulator: the minimum off time (that sets the
maximum duty cycle), and the on state resistance.
When operating in continuous conduction mode (CCM),
the output voltage is equal to the input voltage multiplied by
the duty ratio. Because the NCV890101 needs a sufficient
bootstrap voltage to operate, its duty cycle cannot be 100%:
2 3
Typically, with the recommended 4.7 mH inductor, two
ceramic capacitors of 10 mF each in parallel give very good
results.
Freewheeling diode:
The diode must be chosen according to its maximum
current and voltage ratings, and to thermal considerations.
As far as max ratings are concerned, the maximum reverse
voltage the diode sees is the maximum input voltage (with
some margin in case of ringing on the Switch node), and the
maximum forward current the peak current limit of the
it needs a minimum off time (t
) to periodically re−fuel
OFFmin
the bootstrap capacitor C . This imposes a maximum duty
BST
ratio D
= 1 − t
.F
, with the switching
MAX
OFFmin SW(min)
frequency being folded back down to F
keep regulating at the lowest input voltage possible.
The drop due to the on−state resistance is simply the
voltage drop across the Switch resistance R
= 500 kHz to
SW(min)
NCV890101, I
.
LIM
The power dissipated in the diode is P
:
Dloss
at the
DSON
VOUT
given output current: V
= I
.R
.
SWdrop
OUT DSon
(eq. 5)
@ VF ) IDRMS @ RD
@ ǒ1 * Ǔ
P
Dloss + IOUT
Which leads to the maximum output voltage in low Vin
condition: V = D .V − V
VIN
OUT
MAX IN(min)
SWdrop
with:
− I
the average (dc) output current
EXPOSED PAD
OUT
− V the forward voltage of the diode
The exposed pad (EPAD) on the back of the package must
be electrically connected to the electrical ground (GND pin)
for proper, noise−free operation.
F
− I
the RMS current in the diode:
DRMS
http://onsemi.com
13
NCV890101
For example, using a 4.7 mH input capacitor, it is easy to
2
DIL
2
(
)
IOUT )
calculate that an inductor of 200 nH will ensure that the
input filter has a cut−off frequency below 200 kHz (low
enough to attenuate the 2 MHz ripple).
(eq. 6)
1 * D ǒ
Ǔ
IDRMS
+
Ǹ
12
− R the dynamic resistance of the diode (extracted from
D
the V/I curve of the diode in its datasheet).
PCB LAYOUT RECOMMENDATION
Then, knowing the thermal resistance of the package and
the amount of heatsinking on the PCB, the temperature rise
corresponding to this power dissipation can be estimated.
As with any switching power supplies, there are some
guidelines to follow to optimize the layout of the printed
circuit board for the NCV890101. However, because of the
high switching frequency extra care has to be taken.
− Minimize the area of the power current loops:
♦ Input capacitor ³ NCV890101 switch ³ Inductor
³ output capacitor ³ return through Ground
♦ Freewheeling diode ³ inductor ³ Output capacitor
³ return through ground
Input capacitor:
The input capacitor must sustain the RMS input ripple
current I
:
INac
DIL
D
(eq. 7)
Ǹ
IINac
+
2
3
− Minimize the length of high impedance signals, and
route them far away from the power loops:
♦ Feedback trace
It can be designed in combination with an inductor to build
an input filter to filter out the ripple current in the source, in
order to reduce EMI conducted emissions.
♦ Comp trace
ORDERING INFORMATION
†
Device
NCV890101MWTXG
Package
DFN10 with wettable flanks
Shipping
3000 / Tape & Reel
(Pb−Free)
†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.
http://onsemi.com
14
NCV890101
PACKAGE DIMENSIONS
DFN10, 3x3, 0.5P
CASE 485C
ISSUE B
EDGE OF PACKAGE
D
A
B
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ASME Y14.5M, 1994.
2. CONTROLLING DIMENSION: MILLIMETERS.
3. DIMENSION b APPLIES TO PLATED
TERMINAL AND IS MEASURED BETWEEN
0.25 AND 0.30 MM FROM TERMINAL.
4. COPLANARITY APPLIES TO THE EXPOSED
PAD AS WELL AS THE TERMINALS.
5. TERMINAL b MAY HAVE MOLD COMPOUND
MATERIAL ALONG SIDE EDGE. MOLD
FLASHING MAY NOT EXCEED 30 MICRONS
ONTO BOTTOM SURFACE OF TERMINAL b.
6. DETAILS A AND B SHOW OPTIONAL VIEWS
FOR END OF TERMINAL LEAD AT EDGE OF
PACKAGE.
L1
E
DETAIL A
Bottom View
PIN 1
(Optional)
REFERENCE
EXPOSED Cu
MOLD CMPD
2X
0.15
C
TOP VIEW
MILLIMETERS
2X
0.15
C
DIM MIN
0.80
A1 0.00
MAX
1.00
0.05
A
A3
(A3)
DETAIL B
A3
b
D
0.20 REF
0.10
0.08
C
C
0.18
0.30
A1
3.00 BSC
A
D2 2.40
2.60
DETAIL B
E
3.00 BSC
Side View
SEATING
10X
E2 1.70
1.90
PLANE
(Optional)
e
K
L
0.50 BSC
0.19 TYP
SIDE VIEW
A1
C
0.35
0.45
0.03
L1 0.00
D2
e
DETAIL A
SOLDERING FOOTPRINT*
10X
L
1
5
2.6016
E2
10X
K
1.8508
3.3048
2.1746
10
6
10X b
0.10
0.05
C
C
A
B
BOTTOM VIEW
NOTE 3
10X
0.5651
10X
0.5000 PITCH
0.3008
DIMENSIONS: MILLIMETERS
*For additional information on our Pb−Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
ON Semiconductor and
are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks,
copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent−Marking.pdf. SCILLC
reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any
particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without
limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications
and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC
does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for
surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where
personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and
its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly,
any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture
of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
PUBLICATION ORDERING INFORMATION
LITERATURE FULFILLMENT:
N. American Technical Support: 800−282−9855 Toll Free
USA/Canada
Europe, Middle East and Africa Technical Support:
Phone: 421 33 790 2910
Japan Customer Focus Center
Phone: 81−3−5817−1050
ON Semiconductor Website: www.onsemi.com
Order Literature: http://www.onsemi.com/orderlit
Literature Distribution Center for ON Semiconductor
P.O. Box 5163, Denver, Colorado 80217 USA
Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada
Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada
Email: orderlit@onsemi.com
For additional information, please contact your local
Sales Representative
NCV890101/D
相关型号：
NCV8901AMNTXG
IC 1.7 A SWITCHING REGULATOR, 2200 kHz SWITCHING FREQ-MAX, PDSO8, 3 X 3 MM, 0.50 MM PITCH, LEAD FREE, DFN-8, Switching Regulator or Controller
ONSEMI
©2020 ICPDF网 联系我们和版权申明