NCP4390DR2G [ONSEMI]
Resonant Controller with Synchronous Rectifier Control, Enhanced Light Load;型号: | NCP4390DR2G |
厂家: | ONSEMI |
描述: | Resonant Controller with Synchronous Rectifier Control, Enhanced Light Load |
文件: | 总30页 (文件大小:760K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
DATA SHEET
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Advanced Secondary Side
LLC Resonant Converter
Controller with Synchronous
Rectifier Control
SOIC−16
CASE 751B−05
MARKING DIAGRAM
NCP4390
The NCP4390 is an advanced Pulse Frequency Modulated (PFM)
controller for LLC resonant converters with Synchronous
Rectification (SR) that offers best in class efficiency for isolated
DC/DC converters. It employs a current mode control technique based
on a charge control, where the triangular waveform from the oscillator
is combined with the integrated switch current information to
determine the switching frequency. This provides a better
control−to−output transfer function of the power stage simplifying the
feedback loop design while allowing true input power limit capability.
Closed−loop soft−start prevents saturation of the error amplifier and
allows monotonic rising of the output voltage regardless of load
condition. A dual edge tracking adaptive dead time control minimizes
the body diode conduction time thus maximizing efficiency.
NCP4390
AWLYWWG
1
NCP4390
A
L
Y
WW
G
= Specific Device Code
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
PIN CONNECTIONS
5VB
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
Features
VDD
PWMS
FMIN
FB
• Secondary Side PFM Controller for LLC Resonant Converter with
Synchronous Rectifier Control
• Charge Current Control for Better Transient Response and Easy
Feedback Loop Design
• Adaptive Synchronous Rectification Control with Dual Edge
Tracking
• Closed Loop Soft−Start for Monotonic Rising Output
• Wide Operating Frequency (39 kHz ~ 690 kHz)
PROUT1
PROUT2
SROUT1
COMP
SS
SROUT2
SR1DS
ICS
CS
RDT
• Green Functions to Improve Light−Load Efficiency
♦ Symmetric PWM Control at Light−Load to Limit the Switching
Frequency while Reducing Switching Losses
♦ Disabling SR at Light−Load Condition
ORDERING INFORMATION
See detailed ordering and shipping information on page 3 of
this data sheet.
• Protection Functions with Auto−Restart
♦ Over−Current Protection (OCP)
♦ Output Short Protection (OSP)
♦ NON Zero−Voltage Switching Prevention (NZS) by
Compensation Cutback (Frequency Shift)
♦ Power Limit by Compensation Cutback (Frequency Shift)
♦ Overload Protection (OLP) with Programmable Shutdown Delay
Time
• Programmable Dead Times for Primary Side Switches and Secondary
Side Synchronous Rectifiers
• V Under−Voltage Lockout (UVLO)
DD
• Wide Operating Temperature Range −40°C to +125°C
• This Device is Pb−Free, Halogen Free/BFR Free and is RoHS
Compliant
Applications
• Automotive On Board Charger
• Intelligent 100 W−2 kW+ Off−Line & Industrial Power Supplies
© Semiconductor Components Industries, LLC, 2018
1
Publication Order Number:
November, 2021 − Rev. 2
NCP4390/D
NCP4390
DG1
RG1
VIN
Q1
Q2
RGS1
PRDRV+
SR2
SR1
CIN
DG2
RG2
Ns
VO
SRDRV2
SRDRV1
PRDRV−
Np
COUT
CR
RGS2
Ns
CT
RCS2
RCS1
RSRDS1
CVDD
RSRDS2
C5VB
5VB
GND
PWMS
FMIN
VDD
RPWMS
RFMIN
RFB1
PRDRV+
PROUT1
PROUT2
RICS
FB
PRDRV−
CCOMP
COMP
SS
SRDRV1
SRDRV2
SROUT1
SROUT2
CSS
R
CICS
ICS
CS
SR1DS
RDT
CDT
RDT
Figure 1. Typical Application Schematic of NCP4390
Block Diagram
+
ICS_RST
−
3V
HALF_CYCLE
PWM_CTRL
14
13
PROUT1
PROUT2
+
VCT
1.5V
VSAW
CLK1
CLK2
Digital
PFM/PWM
Block
Dead Time
Control
Block
+
−
−
3
FMIN
COMP_I
PWM
3/4
1V
CT_RST
CT_RST
7
ICS
Dead Time
Setting
3
RDT
OCP2
Protection
Block
ICS_RST
SR_SKIP
Current
Analyzer
SHUTDOWN
SKIP
Auto−Restart
Control
SR_SHRNK
DOWN
UP1
UP4
SR_SKIP
PWMM
SR STOP
RST
RST
5V
Compensation
Cutback signal
Generator
12
11
SROUT1
SROUT2
6
SS
PROUT1
PROUT2
Dual Edge Adaptive
Tracking SR Control Block
+
SR_SHRNK
+
OSP
5
COMP
−
SR1_CND
SR2_CND
−
1.2V
2.4V
SR Conduction Detect
Block
4
10
15
FB
SR1DS
VDD
PWM Mode
Entry Level
Setting
+
PWM_CTRL
2
+
PWMS
PWMM
−
−
8.5V/10V
NON ZVS
Detect
8
1 5VB
BIAS
CS
VDD_GOOD
−
+
−3.5V
+
16
GND
OCP2
−
3.5V
Figure 2. Internal Block Diagram of NCP4390
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2
NCP4390
PIN DESCRIPTION
Pin Number
Pin Name
5VB
Description
1
2
5 V REF
PWMS
FMIN
PWM mode entry level setting.
Minimum frequency setting pin.
3
4
FB
Output voltage sensing for feedback control.
Output of error amplifier.
5
COMP
SS
6
Soft−start time programming pin.
7
ICS
Current information integration pin for current mode control.
Current sensing for over current protection.
Dead time programming pin for the primary side switches and secondary side SR switches.
SR1 Drain−to−source voltage detection.
Gate drive output for the secondary side SR MOSFET 2.
Gate drive output for the secondary side SR MOSFET 1.
Gate drive output 2 for the primary side switch.
Gate drive output 1 for the primary side switch.
IC Supply voltage.
8
CS
9
RDT
10
11
12
13
14
15
16
SR1DS
SROUT2
SROUT1
PROUT2
PROUT1
VDD
GND
Ground.
ORDERING AND SHIPPING INFORMATION
†
Ordering Code
Device Marking
NCP4390
Package
Shipping
NCP4390DR2G
SOIC−16
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.
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3
NCP4390
MAXIMUM RATINGS
Symbol
Parameter
Min
Max
Unit
VDD Pin Supply Voltage to GND
5VB Pin Voltage
−0.3
20.0
V
V
DD
−0.3
−0.3
−0.3
−0.3
−0.3
−0.3
−0.5
−5.0
−0.3
−0.3
−0.3
−0.3
−0.3
−0.3
−40
5.5
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
V
V
V
5VB
PWMS Pin Voltage
FMIN Pin Voltage
FB Pin Voltage
V
PWMS
V
V
FMIN
V
V
FB
COMP Pin Voltage
SS Pin Voltage
V
V
COMP
V
V
SS
ICS Pin Voltage
V
V
ICS
CS Pin Voltage
V
V
CS
RDT Pin Voltage
V
V
RDT
SR1DS Pin Voltage
PROUT1 Pin Voltage
PROUT2 Pin Voltage
SROUT1 Pin Voltage
SROUT2 Pin Voltage
Junction Temperature
V
V
SR1DS
PROUT1
PROUT2
SROUT1
SROUT2
V
DD
V
V
V
V
V
V
DD
V
V
DD
V
V
DD
V
150
260
150
2
°C
°C
°C
kV
T
J
Lead Soldering Temperature (10 Seconds)
Storage Temperature
T
L
−65
T
STG
Human body Model,
ANSI / ESDA / JEDEC
Electrostatic Discharge
Capability
ESD
JS−001−2012
Charged Device Model,
JESD22−C101
1
kV
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
All voltage values are with respect to the GND pin.
THERMAL CHARACTERISTICS
Symbol
Rθ
Rating
Value
Unit
Junction−to−Ambient Thermal Characteristics
115
°C/W
JA
RECOMMENDED OPERATING CONDITIONS
Symbol
Parameter
Min.
0
Max.
18
Unit
V
DD
VDD Pin Supply Voltage to GND
5VB Pin Voltage
V
V
V
5VB
0
5
V
INS
Signal Input Voltage
0
5
V
T
J
Operating Junction Temperature
−40
+125
°C
Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond
the Recommended Operating Ranges limits may affect device reliability.
Allowable operating ambient temperature can be limited by the power dissipation of NCP4390.
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NCP4390
ELECTRICAL CHARACTERISTICS (V = 12 V, C
= 33 nF and T = −40°C to 125°C unless otherwise specified)
DD
5VB
J
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
SUPPLY VOLTAGE (VDD PIN)
I
Startup Supply Current
Operating Current
V
V
= 9 V
80
2.8
10
115
mA
mA
mA
STARTUP
DD
I
= 0.1 V, V = 3 V, V = 0 V
FB SS
DD
COMP
I
I
Dynamic Operating Current
f
= 100 kHz; C = 1 nF, with PR
DD_DYM1
SW L
Operation Only
Dynamic Operating Current
f
= 100 kHz; C = 1 nF, with PR &
13
mA
DD_DYM2
SW
L
SR Operation
V
VDD ON Voltage (VDD Rising)
9
10
11
V
V
DD.ON
V
VDD OFF Voltage
(VDD Falling)
8.6
DD.OFF
V
UVLO Hysteresis
0.9
1.4
1.9
V
DD.HYS
REFERENCE VOLTAGE
5 V Reference
V
4.99
4.90
5.05
5.05
5.11
5.20
V
V
T = 25°C
5VB
J
−40°C < T < 125°C
J
ERROR AMPLIFIER (COMP PIN)
V
Voltage Feedback Reference
2.37
2.34
2.40
2.40
300
2.43
2.46
T = 25°C
V
V
SS.CLMP
J
−40°C < T < 125°C
J
gm
Error Amplifier Gain
Transconductance
mmho
I
Error Amplifier Maximum
Output Current (Sourcing)
V
FB
V
FB
V
FB
= 1.8 V, VCOMP = 2.5 V
= 3.0 V, VCOMP = 2.5 V
= 1.8 V
65
65
90
90
115
115
4.6
mA
mA
V
COMP1
I
Error Amplifier Maximum
Output Current (Sinking)
COMP2
V
Error Amplifier Output High
Clamping Voltage
4.2
4.4
COMP.CLMP1
V
V
Internal Clamping
RPWM = 130 k
RPWM = 82 k
RPWM = 82 k
1.26
1.4
1.41
1.6
1.56
1.8
V
V
V
V
COMP.PWM
COMP
Voltage for PWM Operation
V
PWMS
PWMS Pin Voltage
1.9
2.0
2.1
V
VCOMP Threshold for Entering
Skip Cycle Operation
1.15
1.25
1.35
COMP.SKP
V
VCOMP Threshold Hysteresis
for Entering Skip Cycle
Operation
50
mV
COMP.SKP.HYS
DEAD TIME (DT PIN)
I
Dead−Time Programming
V
RDT
= 1.2 V
140
0.9
2.8
1.2
150
1.0
3.0
1.4
160
1.1
3.2
1.6
mA
V
DT
Current
V
V
First Threshold for Dead−Time
Detection
THDT1
Second Threshold for
Dead−Time Detection
V
THDT2
V
V
Voltage
V
RDT.ON
RDT ON
(VRDT Rising)
SOFT−START (SS PIN)
I
Total Soft−Start Current
V
V
= 1 V
= 3 V
32
40
52
mA
SS.T
SS
(Including I
)
SS.UP
V
Overload Protection Threshold
3.45
8.2
3.60
10.5
3.75
12.8
V
OLP
I
Soft−Start Capacitor Charge
Current for Delayed Shutdown
mA
SS.UP
SS
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NCP4390
ELECTRICAL CHARACTERISTICS (V = 12 V, C
= 33 nF and T = −40°C to 125°C unless otherwise specified)
DD
5VB
J
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
SOFT−START (SS PIN)
I
Soft−Start Capacitor Discharge
V
SS
= 3 V
8.2
4.5
10.5
4.7
12.8
4.9
mA
V
SS.DN
Current
V
SS Capacitor Maximum
Charging Voltage
SS.MAX
V
SS Capacitor Initialization
Voltage
0.01
0.10
0.20
V
SS.INIT
FEEDBACK (FB PIN)
V
VFB Threshold for Entering
Skip Cycle Operation
V
V
V
= 3 V
= 3 V
2.53
2.18
1.0
2.65
2.30
1.2
2.77
2.42
1.4
V
V
V
FB.OVP1
FB.OVP2
ERR.OSP
COMP
V
VFB Threshold for Exiting Skip
Cycle Operation
COMP
V
Error Voltage to Enable Output
Short Protection (OSP)
= 2.4 V
SS
OSCILLATOR
V
FMIN Pin Voltage
R
R
= 10 kW,
1.4
95
1.5
1.6
V
FMIN
OSC
FIMN
f
PROUT Switching Frequency
= 10 kW, V = 1 V
= 4.0 V, V
100
105
kHz
MINF
CS
ICS
V
= 0 V
COMP
f
Minimum PROUT Switching
Frequency (40 MHz/1024)
R
COMP
= 40 kW, V = 1 V
36
39
690
50
42
kHz
kHz
%
OSC.min
MINF
CS
V
= 4.0 V, V
= 0 V
ICS
f
Maximum PROUT Switching
Frequency (40 MHz/58)
R
= 2 kW, V = 1 V
635
735
OSC.max
MINF
CS
ICS
V
COMP
= 2.0 V, V
= 0 V
D
PROUT Duty Cycle in PFM
Mode
R
= 20 kW, V = 1 V
MINF
CS
V
COMP
= 4.0 V
INTEGRATED CURRENT SENSING (ICS PIN)
V
ICS Pin Signal Clamping Voltage
ICS Pin Clamping MOSFET
I
I
= 400 mA
10
20
50
mV
ICS.CLMP
CS
R
= 1.5 mA
W
.
CS
DS−ON ICS
R
DS−ON
V
SR_SHRNK Enable Threshold
SR_SHRNK Disable Hysteresis
SR_SKIP Disable Threshold
SR_SKIP Enable Threshold
V
COMP
V
COMP
V
COMP
V
COMP
V
COMP
= 2.4 V
0.15
0.20
50
0.25
V
mV
V
TH1
V
= 2.4 V
= 2.4 V
= 2.4 V
= 2.4 V
TH1.HYS
V
V
0.10
0.025
1.12
0.15
0.075
1.20
0.20
0.125
1.28
TH2
V
TH3
V
OCL1
Over−Current Limit First
Threshold
V
V
Over−Current Limit Second
V
V
= 2.4 V
= 2.4 V
1.34
1.34
1.45
1.45
1.56
1.56
V
V
OCL2
COMP
Threshold
V
V
Over-Current Limit First
Threshold in Deep Below
Resonance Operation
OCL1.BR
COMP
Over−Current Limit Second
Threshold in Deep Below
Resonance Operation
V
COMP
= 2.4 V
1.59
1.70
1.81
V
OCL2.BR
V
Over−Current Protection
V
V
= 2.4 V
= 2.4 V
1.77
2.02
1.90
2.15
150
2.03
2.28
V
V
OCP1
COMP
Threshold
V
Over−Current Protection
Threshold
OCP1.BR
COMP
T
Debounce Time for Over−Current
Protection 1
ns
OCP1.DLY
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NCP4390
ELECTRICAL CHARACTERISTICS (V = 12 V, C
= 33 nF and T = −40°C to 125°C unless otherwise specified)
DD
5VB
J
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
CURRENT SENSING (CS PIN)
V
Over−Current Protection
3.3
3.5
150
−3.5
0.30
3.0
3.7
V
ns
V
OCP2P
Threshold
T
Debounce Time for Over−Current
Protection 2
OCP2.DLY
V
Over−Current Protection
Threshold
−4.0
0.24
2.7
−3.0
0.36
3.3
OCP2N
V
CS Signal Threshold for Non-ZVS
Detection
V
= 3.5 V
COMP
V
CS.NZVS
V
COMP Threshold for Non-ZVS
Detection
V
CS
= 0.1 V
V
COMP.NZVS
GATE DRIVE (PROUT1 AND PROUT2)
I
PROUT Sinking Current
PROUT Sourcing Current
Rise Time
V
V
V
V
& V
& V
= 6 V
= 6 V
140
150
100
85
mA
mA
ns
SINK
PROUT1
PROUT2
I
SOURCE
PROUT1
PROUT2
t
= 12 V, C = 1 nF, 10% to 90%
L
PR.RISE
PR.FALL
DD
DD
t
Fall Time
= 12 V, C = 1 nF, 90% to 10%
ns
L
SYNCHRONOUS RECTIFICATION (SR) CONTROL
TRC_SRCD
(Note 1)
Internal RC Time Constant SR
Conduction Detection
50
100
0.25
0.20
150
0.35
0.30
0.6
ns
V
VSRCD.OFFSET1
(Note 1)
Internal Comparator Offset Rising
Edge Detection
0.15
0.10
0.4
VSRCD.OFFSET2
(Note 1)
Internal Comparator Offset
Falling Edge Detection
V
V
SR Conduction Detect threshold
0.5
65
V
SRCD.LOW
DLY.CMP.SR
T
SR Conduction Detect
Comparator Delay
ns
V
SR Enable FB Voltage
SR Disable FB Voltage
1.6
1.0
1.8
1.2
2.0
1.4
V
V
.
.
FB SR ON
V
.
.
FB SR OFF
SR OUTPUT (SROUT1 AND SROUT2)
PROUT Sinking Current
V
V
V
V
& V
& V
= 6 V
= 6 V
140
150
100
85
mA
mA
ns
I
SROUT1
SROUT2
SR.SINK
PROUT Sourcing Current
Rise Time
I
SROUT1
SROUT2
SR.SOURCE
= 12 V, C = 1 nF, 10% to 90%
t
DD
DD
L
SR.RISE
Fall Time
=12 V, C = 1 nF, 90% to 10%
ns
t
L
SR.FALL
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product
performance may not be indicated by the Electrical Characteristics if operated under different conditions.
1. These parameters, although guaranteed by design, are not production tested.
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NCP4390
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 3. V5VB vs. Temperature
Figure 4. IDT vs. Temperature
Figure 5. VFMIN vs. Temperature
Figure 6. fOSC vs. Temperature
Figure 7. fOSC.MIN vs. Temperature
Figure 8. fOSC.MAX vs. Temperature
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NCP4390
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 9. DUTY CYCLE vs. Temperature
Figure 10. VRDT.OFF vs. Temperature
Figure 11. VSS.CLMP vs. Temperature
Figure 12. ISTARTUP vs. Temperature
Figure 13. IDD vs. Temperature
Figure 14. IDD_DYM1 vs. Temperature
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NCP4390
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 15. IDD_DYM2 vs. Temperature
Figure 16. VDD.ON vs. Temperature
Figure 18. VDD.HYS vs. Temperature
Figure 17. VDD.OFF vs. Temperature
Figure 19. gm vs. Temperature
Figure 20. ICOMP1 vs. Temperature
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NCP4390
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 21. ICOMP2 vs. Temperature
Figure 22. VCOMP.CLMP1 vs. Temperature
Figure 23. VCOMP.PWM vs. Temperature
Figure 24. VCOMP.SKIP vs. Temperature
Figure 25. VCOMP.SKIP.HYS vs. Temperature
Figure 26. VRDT.ON vs. Temperature
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NCP4390
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 27. VTHDT1 vs. Temperature
Figure 28. VTHDT2 vs. Temperature
Figure 30. VOLP vs. Temperature
Figure 32. VSS.MAX vs. Temperature
Figure 29. ISS.T vs. Temperature
Figure 31. ISS.UP vs. Temperature
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NCP4390
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 33. ISS.DN vs. Temperature
Figure 34. VSS.INIT vs. Temperature
Figure 36. VFB.OVP1 vs. Temperature
Figure 38. VERR.OSP vs. Temperature
Figure 35. VPWMS vs. Temperature
Figure 37. VFB.OVP1 vs. Temperature
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NCP4390
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 39. RDS−ON.ICS vs. Temperature
Figure 40. VTH1 vs. Temperature
Figure 41. VTH1 vs. Temperature
Figure 42. VTH3 vs. Temperature
Figure 43. VOCL1 vs. Temperature
Figure 44. VOCL2 vs. Temperature
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NCP4390
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 45. VOCL1.BR vs. Temperature
Figure 46. VOCL2.BR vs. Temperature
Figure 47. VOCP1 vs. Temperature
Figure 48. VOCP1.BR vs. Temperature
Figure 49. VOCP2P vs. Temperature
Figure 50. VOCP2N vs. Temperature
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NCP4390
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 51. VCS.NZVS vs. Temperature
Figure 52. VCOMP.NZVS vs. Temperature
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NCP4390
APPLICATION INFORMATION
Operation Principle of Charge Current Control
current flowing out of the FMIN pin. The FMIN pin voltage
is regulated at 1.5 V.
The LLC resonant converter has been widely used for
many applications because it can regulate the output over
entire load variations with a relatively small variation of
switching frequency, and achieve Zero Voltage Switching
(ZVS) for the primary side switches and Zero Current
Switching (ZCS) for the secondary side rectifiers over the
entire operating range. In addition, the resonant inductance
can be integrated with the transformer into a single magnetic
component. Figure 53 shows the simplified schematic of the
LLC resonant converter where voltage mode control is
employed. Voltage mode control is typically used for the
LLC resonant converter where the error amplifier output
voltage directly controls the switching frequency. However,
the compensation network design of the LLC resonant
converter is relatively challenging since the frequency
response with voltage mode control includes four poles
where the location of the poles changes with input voltage
and load variations.
Q1
VIN
VO
CO
Cr
Lr
Q2
L
VCO
VC
VO.REF
+
Vc
Driver
−
Figure 53. LLC Resonant Converter with Voltage
Mode Control
NCP4390 employs charge current mode control to
improve the dynamic response of the LLC resonant
converter. Figure 54 shows the simplified schematic of a
half−bridge LLC resonant converter using NCP4390, where
Lm is the magnetizing inductance, Lr is the resonant
inductor and Cr is the resonant capacitor. Typical key
waveforms of the LLC resonant converter for heavy load
and light load conditions are illustrated in Figure 55 and
Figure 56, respectively. It is assumed that the operation
frequency is same as the resonance frequency, as determined
by the resonance between Lr and Cr. Since the primary−side
switch current does not increase monotonically, the switch
VIN
Q1
PROUT1
PROUT2
Cr
Lr
VO
Q2
Lm
Current
sensing
ICS
3/4
Integrated signal (VICS
)
VSAW
Reset
VREF
+
−
VCT
CT
Digital
OSC
1.5V
1V
PROUT1
PROUT2
+
+
current
itself
cannot
be
used
for
−
−
3V
pulse−frequency−modulation (PFM) for the output voltage
regulation. Also, the peak value of the primary−side current
does not reflect the load condition properly because the large
circulating current (magnetizing current) is included in the
primary−side switch current. However, the integral of the
FMIN
SS
VCOMP.I
PWM
VCOMP.I
VSAW
control
1V
U1
COMP
Cutback
2.4V
PROUT1
VCOMP
COMP
PROUT2
switch current (V ) does increase monotonically and has
ICS
PWMS
FB
a peak value similar to that used for peak current mode
control, as shown in Figure 55 and Figure 56.
Thus, NCP4390 employs charge current control, which
compares the total charge of the switch current (integral of
switch current) to the control voltage to modulate the
switching frequency. Since the charge of the switch current
is proportional to the average input current over one
switching cycle, charge control provides a fast inner loop
and offers excellent transient response including inherent
line feed−forward. The PFM block has an internal timing
capacitor (CT) whose charging current is determined by the
Figure 54. Schematic of LLC resonant Converter
Power Stage Schematic
There is an upper limit (3 V) for the timing capacitor
voltage, which determines the minimum switching
frequency for a given resistor connected to the FMIN pin.
The sawtooth waveform (V ) is generated by adding the
SAW
integral of the Q1 switch current (V ) and the timing
ICS
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17
NCP4390
capacitor voltage (V ) of the oscillator. The sawtooth
waveform (Vsaw) is then compared with the compensation
To improve the light load efficiency, NCP4390 employs
hybrid control where the PFM is switched to pulse width
modulation (PWM) mode at light load as illustrated in
Figure 57. If want to not uses PWM mode in light load
condition, adjust PWM entry level using external PWM
resistor for under skip threshold level. The figure 58 show
that the switching frequency and duty ratio characteristics in
disable PWM mode. The typical waveforms for PFM mode
and PWM mode are shown in Figure 59 and Figure 60,
respectively. When the error amplifier voltage (VCOMP) is
below the PWM mode threshold, the internal COMP signal
is clamped at the threshold level and the PFM operation
switches to PWM mode.
CT
voltage (V ) to determine the switching frequency.
COMP
Ip
Im
ID
IDS1
Switching
frequency
Duty cycle
PFM Mode
PWM Mode
Skip cycle
D=50%
No
switching
V
ICS =
k ∫ I
dt
DS1
VCOMP
4.4V
1.3V
1.25V
VCOMP.PWM
Figure 55. Typical Waveforms of the LLC
Resonant Converter for Heavy Load Condition
Figure 57. Mode Change with COMP Voltage
Duty cycle
Switching
Ip
frequency
Skip cycle
PFM Mode
D=50%
Im
No
switching
ID
VCOMP.PWM = Less than 1.25 V
( Disable PWM mode )
VCOMP
4.4V
1.3V
1.25V
Figure 58. Disable PWM mode with COMP Voltage
IDS1
Ip
Im
VICS
VCT
V
ICS =
k ∫ I
dt
DS1
VCOMP
Figure 56. Typical Waveforms of LLC Resonant
3/4*VICS+VCT
Converter for Light−Load Condition
Counter of
Hybrid Control (PWM + PFM)
The conventional PFM control method modulates only
the switching frequency with a fixed duty cycle of 50%,
which typically results in relatively poor light load
efficiency due to the large circulating primary side current.
PROUT1
PROUT2
Figure 59. Key Waveforms of PFM Operation
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18
NCP4390
Ip
VCTX
VICS
Q1
VICS
VCT
PROUT1
RICS
PROUT1
VICS
PROUT1
Current
transformer
VCOMP.PWM −V
COMP
ICS
VICS
+
+
VSENSE
CICS
VCOMP.PWM −V
COMP
VTH.PWM
3/4*VICS+VCT
VCOMP
−
−
PROUT1
Q2
RCS2
Counter of
digital OSC
CS
VCS
PROUT2
Main
RCS1
transformer
PROUT1 PROUT2
Primary
winding
Figure 60. Key Waveforms of PWM Operation
Figure 61. Current Sensing of NCP4390
In PWM mode, the switching frequency is fixed by the
clamped internal COMP voltage (VCOMPI) and the duty
cycle is determined by the difference between COMP
voltage and the PWM mode threshold voltage. Thus, the
duty cycle decreases as VCOMP drops below the PWM
mode threshold, which limits the switching frequency at
light load condition as illustrated in Figure 57. The PWM
mode threshold can be programmed between 1.9 V and
under skip threshold using a resistor on the PWMS pin.
Disable PWM mode when the PWM mode threshold is set
below 1.25 V.
1
0.8
0.6
0.4
0.2
0
∫ V
CTX
dt
VICS
4
3
2
1
VCTX
0
−1
−2
−3
−4
Current Sensing
NCP4390 senses instantaneous switch current and the
integral of the switch current as illustrated in Figure 61.
Since NCP4390 is located in the secondary side, it is typical
to use a current transformer for sensing the primary side
current. While the PROUT1 is LOW, the ICS pin is clamped
at 0 V with an internal reset MOSFET. Conversely, while
PROUT1 is high, the ICS pin is not clamped and the integral
Figure 62. Disable PWM mode with COMP Voltage
Since the peak value of the integral of the current sensing
voltage (VICS) is proportional to the average input current
of the LLC resonant converter, it is used for four main
functions, listed and shown in Figure 63.
1. SR Gate Shrink: To guarantee stable SR operation
during light load operation, the SR dead time (both
of turn−on and turn−off transitions) is increased
capacitor (C ) is charged and discharged by the voltage
ICS
difference between the sensing resistor voltage (V
)
SENSE
and the ICS pin voltage. During normal operation, the
voltage of the ICS pin is below 1.2 V since the power limit
threshold is 1.2 V. The current sensing resistor and current
transformer turns ratio should be designed such that the
resulting in SR gate shrink when V peak value
ICS
drops below V
(0.2 V). The SR dead time is
TH1
reduced to the programmed value when V peak
ICS
value rises above 0.25 V
voltage across the current sensing resistor (V
) is
SENSE
2. SR Disable and Enable: During very light−load
greater than 4 V at the full load condition. Therefore the
current charging and discharging C should be almost
condition, the SR is disabled when the V peak
ICS
ICS
value is smaller than V
(0.075 V). When the
proportional to the voltage across the current sensing
resistor (V ). Figure 62 compares the VICS signal and
TH3
V
ICS
peak value increases above V
(0.15 V),
TH2
SENSE
the SR is enabled
the ideal integral signal when the amplitude of V
is
SENSE
4 V. As can be seen, there is about 10% error in the VICS
signal compared to the ideal integral signal, which is
acceptable for most designs. If more accuracy of the VICS
is required, the amplitude of V
should be increased.
SENSE
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19
NCP4390
3. Over−Current Limit: The V peak value is also
ICS
IPR
used for input current limit. As can be seen in
Figure 64, there exist two different current limits
(fast and slow). When the V peak value
increases above the slow current limit level
ICS
PROUT1
VOCP1
(V
) due to a mild overload condition, the
VOCL2
VOCL1
OCL1
internal feedback compensation voltage is slowly
reduced to limit the input power. This continues
until the V peak value drops below V
.
ICS
OCL1
(a) Mild Overload Condition
During a more severe over load condition, the
peak value crosses the fast current limit
V
ICS
IPR
threshold (V
) and the internal feedback
OCL2
compensation voltage is quickly reduced to limit
the input power as shown in Figure 64 (b). This
continues until the V peak value drops below
ICS
PROUT1
V
OCL2
. The current limit threshold on the V
ICS
V
OCP1
peak value also changes as the output voltage
VOCL2
VOCL1
sensing signal (V ) decreases such that output
FB
current is limited during overload condition as
shown in Figure65. In addition, these limit
(b) Severe Overload Condition
thresholds change to higher values (V
and
OCL1.BR
Figure 64. Current Limit of the ICS Pin by
Frequency Shift (Compensation Cutback)
V
) when the converter operates in deep
OCL2.BR
below resonance operation for a longer holdup
time (refer to holdup time boost function)
4. Over−Current Protection (OCP1): When the V
ICS
peak value is larger than V
(1.9 V), the over
OCP1
VOCL2
VOCL1
1.45V
1.2V
current protection is triggered. 150 ns debounce
time is added for over−current protection. These
OCP threshold can be changed to a higher value
1.0V
0.75V
0.5V
(V
) when the converter operates in deep
OCP1.BR
below resonance operation for a longer holdup
time (refer to holdup time boost function)
Output Power
VFB
2.4 V
2.0 V
Fast Current limit
Slow Current limit
Figure 65. Current Limit Threshold Modulation as
a Function of Feedback Voltage
SR Shrink
SR Enable
SR Disable
PK
50mV
VICS
1.2V 1.45V
0.075V
0.15V
0.2V
VICS
Figure 63. Functions Related to VICS Peak Voltage
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20
NCP4390
The instantaneous switch current sensing on the CS pin is
also used for the following functions.
Compensation
Voltage
COMP
+
−
3V
1. Non−ZVS Prevention: When the compensation
0.3V
+
Q
D
−
voltage (V
) is higher than 3 V and V peak
COMP
CS
NON ZVS
detect
PFM block
QN
PROUT1
value is smaller than 0.3 V at PROUT1 falling
edge, non−ZVS condition is detected, which
decreases the internal compensation signal to
increase the switching frequency
+
− 3.5V
−
Compensation
Cutback
OCP2
CS
+
OCP
−
3.5V
1.9V
ICS
+
2. Over−Current Protection (OCP2): When V is
CS
−
OCP1
D
higher than 3.5 V or lower than −3.5 V,
0.25V /
0.20V
+
SR Shrink
SR Skip
Q
over−current protection (OCP2) is triggered. The
instantaneous primary side current is also sensed
on CS pin. Since the OCP2 thresholds on the CS
pin are 3.5 V and −3.5 V as shown in Figure 66,
−
QN
PROUT1
0.15V /
0.075V
+
Q
D
−
QN
PROUT1
the CS signal is typically obtained from V
by using a voltage divider as illustrated in
Figure 61. 150 ns debounce time is also added for
OCP2
+
SENSE
Q
D
D
−
OCL1
Compensation
Cutback
QN
PROUT1
+
Q
OCL2
−
QN
PROUT1
Figure 67 shows utilization of current sensing by using
ICS and CS signals.
Figure 67. Utilization of Current Sensing Signal
VOCP2P
(3.5)V
VCS
VOCP2N
(−3.5V)
PROUT1
PROUT2
VOCP2P
(3.5)V
VCS
VOCP2N
(−3.5V)
PROUT1
PROUT2
Figure 66. Over−Current Protection of the CS Pin
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21
NCP4390
VSS
Soft−Start and Output Voltage Regulation
4.8V
3.6V
Figure 68 shows the simplified circuit block for feedback
control and closed loop soft−start. During normal, steady
state operation, the Soft−Start (SS) pin is connected to the
non−inverting input of the error amplifier which is clamped
at 2.4 V. The feedback loop operates such that the sensed
output voltage is same as the SS pin voltage. During startup,
2.4V
time
time
Ip
an internal current source (I
) charges the SS capacitor
SS.T
and SS pin voltage progressively increases. Therefore, the
output voltage also rises monotonically as a result of closed
loop SS control.
The SS capacitor is also used for the shutdown delay time
during overload protection (OLP). Figure 69 shows the OLP
waveform. During normal operation, the SS capacitor
voltage is clamped at 2.4 V. When the output is over−loaded,
Figure 69. Delayed Shutdown with Soft−Start
Auto−Restart after Protection
All protections of NCP4390 are non−latching,
auto−restart, where the delayed restart is implemented by
charging and discharging the SS capacitor as illustrated in
Figure 70. During normal operation, the SS capacitor
voltage is clamped at 2.4 V. Once any protection is triggered,
the SS clamping circuit is disabled. The SS capacitor is then
V
COMP
is saturated to HIGH and the SS capacitor is
decoupled from the clamping circuit through the SS control
block. I is blocked by D and the SS capacitor is
SS
BLCK
slowly charged up by the current source I . When the SS
SS.UP
capacitor voltage reaches 3.6 V, OLP is triggered. The time
required for the soft−start capacitor to be charged from 2.4 V
to 3.6 V determines the shutdown delay time for overload
protection.
charged up to 4.7 V by an internal current source (I
).
SS.UP
The SS capacitor is then discharged down to 0.1 V by
another internal current (I ). After charging and
SS.DN
discharging the SS capacitor three more times, auto recovery
is enabled.
VIN
Q1
Discharged by ISS.DN
VSS
Cr
Lr
1/8 time scale
Charged by ISS.UP
4.7V
3.6V
Q2
VO
2.4V
Charged by ISS.T
Lm
0.1V
Shutdown
delay
time
Ip
time
PROUT2
PROUT1
ICS
1.2V
PFM
UP
DN
SS
Control
time
time
VCOMP
ISS
ISS.UP
10 mA
Disable SS
30 mA
SS
clamp
Figure 70. Auto Re−Start after Protection is
ISS.DN
2.4V
Triggered
DBLCK
10 mA
COMP
FB
Figure 68. Schematic of Closed Loop Soft−Start
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22
NCP4390
5VB
Output Short Protection
To minimize the power dissipation through the power
stage during a severe fault condition, NCP4390 offers
Output Short Protection (OSP). When the output is heavily
over−loaded or short circuited, the feedback voltage (output
voltage sensing) does not follow the reference voltage of the
error amplifier (2.4 V). When the difference between the
reference voltage of the error amplifier and the FB voltage
is larger than 1.2 V, the OSP is triggered without waiting
until the OLP is triggered as shown in Figure 71.
RDT
VRDT
IDT
S1
CDT
Figure 72. Internal Current Source for of RDT Pin
Dead−Time Setting
With a single pin (RDT pin), the dead times between the
primary side gate drive signals (PROUT1 and PROUT2)
and secondary side SR gate drive signal (SROUT1 and
SROUT2) are programmed using a switched current source
as shown in Figure 72 and Figure 73. Once the 5 V bias is
enabled, the RDT pin voltage is pulled up. When the RDT
TSET1 / 64= SROUT Dead Time
T
SET2 / 32 =PROUT Dead Time
5V
4V
3V
2V
1V
pin voltage reaches 1.4 V, the voltage across C is then
DT
discharged down to 1 V by an internal current source I
.
DT
I
is then disabled and the RDT pin voltage is charged up
DT
TSET1
TSET2
by the RDT resistor. As shown in Figure 73, 1/64 of the time
required (T ) for RDT pin voltage to rise from 1 V to 3 V
Figure 73. Multi−function Operation of RDT Pin
SET1
determines the dead time between the secondary side SR
gate drive signals.
The minimum and maximum dead times are therefore
limited at 75 ns and 375 ns respectively. To assure stable SR
operation while taking circuit parameter tolerance into
account, 75 ns dead time is not recommended especially for
the SR dead time.
When NCP4390 operates in PWM mode at light−load
condition, the dead time is doubled to reduce the switching
loss.
The switched current source I is then enabled and the
DT
RDT pin voltage is discharged. 1/32 of the time required
(T
) for the RDT pin voltage to drop from 3 V to 1 V
SET2
determines the dead time between the primary side gate
drive signals. After the RDT voltage drops to 1 V, the current
source I is disabled a second time, allowing the RDT
DT
voltage to be charged up to 5 V.
Table 1 shows the dead times for SROUT and PROUT
programmed with recommended RDT and CDT component
values. Since the time is measured by an internal 40 MHz
clock signal, the resolution of the dead time setting is 25 ns.
4.8V
3.6V
2.4V
VSS
1.2V
VFB
Ip
time
VICS
1.2V
0.0V
time
Figure 71. Output Short Protection
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23
NCP4390
Table 1. DEAD TIME SETTING FOR PROUT AND SROUT
C
DT
= 180 pF
C
DT
= 220 pF
C
DT
= 270pF
C
DT
= 330 pF
C
DT
= 390 pF
C
DT
= 470 pF
C
DT
= 560 pF
SROUT PROUT SROUT PROUT SROUT PROUT SROUT PROUT SROUT PROUT SROUT PROUT SROUT PROUT
DT (ns) DT (ns) DT (ns) DT (ns) DT (ns) DT (ns) DT (ns) DT (ns) DT (ns) DT (ns) DT (ns) DT (ns) DT (ns) DT (ns)
R
DT
28 k
30 k
33 k
36 k
40 k
44 k
48 k
53 k
58 k
64 k
71 k
78 k
86 k
94 k
104 k
114 k
126 k
138 k
152 k
75
75
375
250
200
175
150
125
125
100
100
100
100
100
75
75
375
325
250
200
175
150
150
125
125
125
125
100
100
100
100
100
100
100
100
75
375
375
300
250
225
200
175
175
150
150
150
150
125
125
125
125
125
125
125
100
100
125
125
150
150
175
200
200
225
250
275
300
325
375
375
375
375
375
375
375
375
325
275
250
225
200
200
200
175
175
175
175
150
150
150
150
150
125
125
150
150
175
175
200
225
250
275
300
325
375
375
375
375
375
375
375
375
375
375
375
325
300
275
250
250
225
225
200
200
200
200
175
175
175
175
150
150
175
175
200
225
250
275
300
325
350
375
375
375
375
375
375
375
375
375
375
375
375
375
350
325
300
300
275
250
250
250
225
225
225
225
225
225
175
175
200
225
250
275
300
325
350
375
375
375
375
375
375
375
375
375
375
375
375
375
375
375
375
375
375
350
325
325
300
300
275
275
275
275
250
250
75
100
100
100
125
125
150
150
175
175
200
225
250
275
300
325
375
375
375
75
75
75
75
75
100
100
125
125
150
150
175
175
200
225
250
275
300
325
350
75
100
100
125
125
150
150
175
175
200
225
250
275
300
75
75
75
75
75
75
Minimum Frequency Setting
The minimum switching frequency is limited by
comparing the timing capacitor voltage (V ) with an
frequency given by the digital oscillator is 39 kHz
(40 MHz/1024 = 39 kHz). Therefore, the maximum
allowable value for R
is 25.5 KW.
CT
FMIN
internal 3 V reference as shown in Figure 74. Since the rising
slope of the timing capacitor voltage is determined by the
PWM Mode Entry Level Setting
When the COMP voltage drops below V
as a
COMP.PWM
resistor (R ) connected to FMIN pin, the minimum
FMIN
result of decreasing load, the internal COMP signal is
clamped at the threshold level and PFM operation switches
to PWM Mode. The PWM entry level threshold is
programmed using a external resistor on the PWMS pin as
shown in Figure 75. Once NCP4390 enters into PWM mode,
the SR gate drives are disabled. If want to uses specially
disable PWM mode, open PWMS pin or connect to 1 MW.
switching frequency is given as:
10 kW
RFMIN
fSW .MIN + 100 kHz
(eq. 1)
The minimum programmable switching frequency is
limited by the digital counter running on an internal 40 MHz
clock. Since a 10 bit counter is used, the minimum switching
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24
NCP4390
Ip
Skip Cycle Operation
As illustrated in Figure 76, when the COMP voltage drops
below V (1.25 V) as a result of decreasing load,
COMP.SKIP
skip cycle operation is employed to reduce switching losses.
As the COMP voltage rises above 1.3 V, the switching
operation is resumed. When the FB voltage rises above
VCOMP
V
(2.65 V), the skip cycle operation is also enabled
FB.OVP1
to limit the output voltage rising quickly. As the FB voltage
VCOMP.SKIP
drops below V
resumed.
(2.3 V), the switching operation is
FB.OVP2
50mV
VCOMP
Figure 76. Skip Cycle Operation
VCOMP
VSAW
NCP4390 uses a dual edge tracking adaptive gate drive
method that anticipates the SR current zero crossing instant
with respect to two different time references. Figure 77 and
Figure 78 show the operational waveforms of the dual edge
tracking adaptive SR drive method operating below and
above resonance. To simplify the explanation, the SR dead
time is assumed to be zero. The first tracking circuit
measures SR conduction time (TSR_CNDCTN) and uses
this information to generate the first adaptive drive signal
(VPRD_DRV1) for the next switching cycle whose duration
is the same as the SR conduction time of previous switching
cycle. The second tracking circuit measures the turn−off
extension time which is defined as time duration from the
falling edge of the primary side drive to the corresponding
SR turn−off instant (TEXT). This information is then used
to generate the second adaptive drive signal (VPRD_DRV2)
for the next switching cycle. When the turn−off of the
primary side drive signal is after the turn−off of the
corresponding SR for below resonance operation, the
second adaptive SR drive signal is the same as the
corresponding primary side gate drive signal. However,
when the turn−off of the primary side drive signal is before
the turn−off instant of the corresponding SR for above
resonance operation, the second adaptive SR drive signal is
generated by extending the corresponding primary side gate
drive signal by TEXT of the previous switching cycle.
Since the turn off instant of the second adaptive gate drive
1V
3V
3V
VCT
1V
VCT
1V
PROUT1
PROUT1
PROUT1
PROUT1
PROUT2
PROUT2
(a) PFM by COM voltage
(b) minimum Frequency limit
ICS
Integrated signal (VICS
)
VSAW
Reset
VREF
+
−
VCT
1.5V
+
Digital
OSC
PROUT1
+
−
−
CT
3V
PROUT2
VSAW
Min Freq Comparator
RFMIN
VCOMP.I
VCOMP.I
FMIN
1V
PWM
control
1V
U1
COMP
Cutback
2.4V
SS
PROUT1
VCOMP
COMP
PROUT2
PWMS
FB
Figure 74. Minimum Switching Frequency Setting
signal is extended by T
with respect to the falling edge
EXT
of the primary side gate drive signal, the duration of this
signal consequentially changes with switching frequency.
By combining these two signals V
and
PRD_DRV1
V
with an AND gate, the optimal adaptive gate
PRD_DRV2
drive signal is obtained.
The SR conduction times for SR1 and SR2 for each
switching cycle are measured using a single pin (SR1DS
pin). The SR1DS voltage and its delayed signal, resulting
Figure 75. PWM Mode Entry Level Setting
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25
NCP4390
SR2_OFF becomes HIGH
if DV>0.2V
from a 100 ns RC time constant, are compared as shown in
SR1_OFF becomes HIGH
if DV>0.25V
Figure 79. When the SR is conducting, the SR1DS voltage
is clamped to either ground or the high voltage rail (2 times
the output voltage) as illustrated in Figure 80. Whereas,
SR1DS voltage changes fast when there is a switching
transition. When both of the SR MOSFETs are turned off,
the SR1DS voltage oscillates. When the SR1DS voltage
changes faster than 0.25 V/100 ns on the rising edge and
0.2 V/100 ns on the falling edge the switching transition of
the SR conduction state is detected. Based on the detected
switching transition, NCP4390 predicts the SR current
zero−crossing instant for the next switching cycle. The
100 ns detection delay caused by the RC time constant is
compensated in the internal timing detection circuit for a
correct gate drive for SR.
100ns
DV
VRC
VSR1DS
V
D
ISR2
0.5V
SR2
100ns
SR1_OFF
SR2_OFF
SR2_OFF
0.5V
ISR1
SR1
+
−
+
SR1_OFF
SR2_OFF
−
0.25V
RDS2
S
R
Q
Q
VSR1DS
SR1DS
VRC
+
RC
=100ns
RDS1
CDS
−
IDS.PRI
IDS.PRI
0.2V
Figure 79. SR Conduction Detection with Single
Pin (SR1DS Pin)
ISR
ISR
TSR_CNDCTN(n+1)
VPROUT
TSR_CNDCTN (n)
Figure 80 and Figure 81 show the typical waveforms of
SR1DS pin voltage together with other key waveforms.
Since the voltage rating of SR1DS pin is 5 V, the voltage
divider should be properly designed such that no
over−voltage is applied to this pin. Additional bypass
capacitor (CDS) can be connected to SR1DS pin to improve
noise immunity. However, the equivalent time constant
generated from the bypass capacitor and voltage divider
resistors should be smaller than the internal RC time
constant (100 ns) of the detection circuit for proper SR
current zero crossing detection.
VPROUT
TSR_CNDCTN* (n−1)
TSR_CNDCTN* (n)
VPRD1(n+1)
TEXT(n+1)
TEXT* (n)
TEXT(n)
V
PRD1(n)
VPRD2 (n)
VPRD2 (n+1)
Figure 77. Operation of Dual Edge Tracking
Adaptive SR Control (below Resonance)
IDS.PRI
IDS.PRI
VSR1.DS
5V
4V
3V
2V
1V
ISR
ISR
T
SR_CNDCTN(n+1)
TSR_CNDCTN(n)
VPROUT
VPROUT
ISR1
ISR2
Ip
TEXT(n)
TEXT(n+1)
TSR_CNDCTN* (n)
TSR_CNDCTN* (n−1)
VPRD1 (n+1)
VPRD1 (n)
TEXT* (n)
VPRD2
V
PRD2 (n)
Figure 78. Operation of Dual Edge Tracking
Adaptive SR Control (above Resonance)
Figure 80. SR Conduction Detection Waveform at
below Resonance Operation
www.onsemi.com
26
NCP4390
VSR1DS
5V
resonance operation during the holdup time as shown in
Figure 82. This holdup time boost operation is enabled when
the SR conduction time is smaller than 94% of the half
switching cycle for longer than 1.6 ms. The current limit
level on ICS pin is recovered to normal value when the SR
conduction time is larger than 98% of the half switching
cycle for longer than 3.2 ms.
4V
3V
2V
1V
ISR1
I
1.7V
VOCL2
1.45V
VOCL1
1.2V
Ip
Ipr
Figure 81. SR Conduction Detection Waveform at
above Resonance Operation
Holdup Time Boost Function
The holdup time of an off−line supply is defined as the
time required for the output voltage to remain within
regulation after the AC input voltage is removed. Since the
input bulk capacitor voltage drops during the holdup time,
more current is taken from the bulk capacitor to deliver the
same power to the load. With a fixed power limit level of
power supply designed for nominal input voltage, the
holdup time tends to be limited due to the increased input
current of the power supply.
SR c onduc tion time
< 94%
Half switc hing period
SR c onduc tion time
Half switc hing period
NCP4390 has a holdup time boost function which
increases the current limit threshold on the ICS pin voltage
when the LLC resonant converter operates in deep below
Figure 82. Holdup Time Boost Function Operation
www.onsemi.com
27
NCP4390
QUICK SETUP GUIDELINE for CURRENT SENSING and SOFT−START
N
N
R
) R
CS1 CS2
Assuming the switching frequency is the same as the
resonance frequency, the peak v of the secondary side
S
P
1
CT
1
1
2
PK
V
+ I
f
t 1.2 V
SW
ICS
O
n
R
C
ICS
ICS
voltage of current transformer (V ) is given as:
SENSE
[example] Io = 20 A, N = 35, N = 2,
n
= 50,
CT
P
S
NS
NP
R
= 30 W, R
= 70 W, R = 10 kW, C = 1 nF,
CS1
CS2 ICS ICS
PK
p
2
1
VSENSE + IO
(RCS1 ) RCS2
)
nCT
f = 100 kHz.
S
PK
³ V
= 1.14 V in nominal load condition (actual
ICS
PK
[example] I = 20 A, N = 35, N = 2,
n
CT
= 50,
V
is lower by about 10% as shown in Figure 62 due to
O
P
S
ICS
PK
R
+ R
= 100 W ³ V
= 3.59 V in nominal
a quasi integral effect).
CS1
CS2
SENSE
PK
PKA
load condition.
Assuming the actual V
(V
) is 1 V, the
ICS
ICS
The voltage divider on the CS pin should be selected such
that OCP is not triggered during normal operation.
soft−start capacitor should be selected such that the overload
protection is not triggered during startup with full load
condition.
NS
NP
PK
p
2
1
VCS + IO
RCS1 t 3.5 V
nCT
C
2.4 V
C
V
SS
OUT
O
T
+
+ 40.8 ms u
+ 22.5 ms
SS
I
PK
SS
1.2*V
ICS
PK
I
[example] I = 21 A, N = 35, N = 2,
n
= 50,
CT
O
O
P
S
V
ICS
PK
R
= 30 W, R
= 70 W ³ V
= 1.131 V in nominal
CS1
CS2
CS
load condition.
The resistor and capacitor on the ICS pin should be
selected such that the current limit is not triggered during
normal operation.
VSENSE
VICS
Q1
PROUT1
PROUT1
PROUT2
PROUT1
PROUT1
Current
transformer
ICS
analyzer
RICS
ICS
Integrated signal (V
)
ICS
+
+
VICS
VSAW
+
VSENSE
VREF
CICS
−
−
Digital
OSC
−
VCT
1.5V
+
+
1:nCT
−
−
CT
3V
RCS2
Primary
side
winding
CS
VCS
RFMIN
Q2
VCOMP.I
VCOMP.I
FMIN
RCS1
1V
U1
NP
PWM
control
+
PROUT2
−
3.5V
OCP
2.4V
SS
COMP
Cutback
+
−3.5V
Main
transformer
NS
NS
−
VCOMP
VO
COMP
PWMS
FB
COUT
Secondary Side winding
Figure 83. Basic Application Circuit for Current Sensing and Soft−Start
www.onsemi.com
28
MECHANICAL CASE OUTLINE
PACKAGE DIMENSIONS
SOIC−16
CASE 751B−05
ISSUE K
DATE 29 DEC 2006
SCALE 1:1
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
−A−
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE.
5. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR PROTRUSION
SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D
DIMENSION AT MAXIMUM MATERIAL CONDITION.
16
9
8
−B−
P 8 PL
M
S
B
0.25 (0.010)
1
MILLIMETERS
INCHES
MIN
0.386
DIM MIN
MAX
MAX
0.393
0.157
0.068
0.019
0.049
A
B
C
D
F
9.80
3.80
1.35
0.35
0.40
10.00
G
4.00 0.150
1.75 0.054
0.49 0.014
1.25 0.016
F
R X 45
K
_
G
J
1.27 BSC
0.050 BSC
0.19
0.10
0
0.25 0.008
0.25 0.004
0.009
0.009
7
K
M
P
R
C
7
0
_
_
_
_
−T−
SEATING
PLANE
5.80
0.25
6.20 0.229
0.50 0.010
0.244
0.019
J
M
D
16 PL
M
S
S
A
0.25 (0.010)
T B
STYLE 1:
STYLE 2:
STYLE 3:
STYLE 4:
PIN 1. COLLECTOR
2. BASE
3. EMITTER
4. NO CONNECTION
5. EMITTER
6. BASE
7. COLLECTOR
8. COLLECTOR
9. BASE
10. EMITTER
11. NO CONNECTION
12. EMITTER
13. BASE
PIN 1. CATHODE
2. ANODE
3. NO CONNECTION
4. CATHODE
5. CATHODE
6. NO CONNECTION
7. ANODE
8. CATHODE
9. CATHODE
10. ANODE
11. NO CONNECTION
12. CATHODE
13. CATHODE
14. NO CONNECTION
15. ANODE
PIN 1. COLLECTOR, DYE #1
2. BASE, #1
3. EMITTER, #1
4. COLLECTOR, #1
5. COLLECTOR, #2
6. BASE, #2
PIN 1. COLLECTOR, DYE #1
2. COLLECTOR, #1
3. COLLECTOR, #2
4. COLLECTOR, #2
5. COLLECTOR, #3
6. COLLECTOR, #3
7. COLLECTOR, #4
8. COLLECTOR, #4
9. BASE, #4
10. EMITTER, #4
11. BASE, #3
12. EMITTER, #3
13. BASE, #2
7. EMITTER, #2
8. COLLECTOR, #2
9. COLLECTOR, #3
10. BASE, #3
11. EMITTER, #3
12. COLLECTOR, #3
13. COLLECTOR, #4
14. BASE, #4
SOLDERING FOOTPRINT
14. COLLECTOR
15. EMITTER
16. COLLECTOR
14. EMITTER, #2
15. BASE, #1
16. EMITTER, #1
15. EMITTER, #4
16. COLLECTOR, #4
8X
6.40
16. CATHODE
16X
1.12
STYLE 5:
STYLE 6:
STYLE 7:
PIN 1. SOURCE N‐CH
PIN 1. DRAIN, DYE #1
2. DRAIN, #1
3. DRAIN, #2
4. DRAIN, #2
5. DRAIN, #3
6. DRAIN, #3
7. DRAIN, #4
8. DRAIN, #4
9. GATE, #4
PIN 1. CATHODE
2. CATHODE
3. CATHODE
4. CATHODE
5. CATHODE
6. CATHODE
7. CATHODE
8. CATHODE
9. ANODE
2. COMMON DRAIN (OUTPUT)
3. COMMON DRAIN (OUTPUT)
4. GATE P‐CH
5. COMMON DRAIN (OUTPUT)
6. COMMON DRAIN (OUTPUT)
7. COMMON DRAIN (OUTPUT)
8. SOURCE P‐CH
1
16
16X
0.58
9. SOURCE P‐CH
10. SOURCE, #4
11. GATE, #3
12. SOURCE, #3
13. GATE, #2
14. SOURCE, #2
15. GATE, #1
16. SOURCE, #1
10. ANODE
11. ANODE
12. ANODE
13. ANODE
14. ANODE
15. ANODE
16. ANODE
10. COMMON DRAIN (OUTPUT)
11. COMMON DRAIN (OUTPUT)
12. COMMON DRAIN (OUTPUT)
13. GATE N‐CH
14. COMMON DRAIN (OUTPUT)
15. COMMON DRAIN (OUTPUT)
16. SOURCE N‐CH
1.27
PITCH
8
9
DIMENSIONS: MILLIMETERS
Electronic versions are uncontrolled except when accessed directly from the Document Repository.
Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red.
DOCUMENT NUMBER:
DESCRIPTION:
98ASB42566B
SOIC−16
PAGE 1 OF 1
ON Semiconductor and
are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries.
ON Semiconductor reserves the right to make changes without further notice to any products herein. ON Semiconductor makes no warranty, representation or guarantee regarding
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