ON NCL30060 High pf offline single stage led driver Datasheet

NCL30060
High PF Offline Single Stage
LED Driver with High
Voltage Startup
The NCL30060 is a switch mode power supply controller intended
for low to medium power single stage power factor (PF) corrected
LED Drivers. It employs a constant on−time control method to ensure
near unity power factor across a wide range of input voltages and
output power. It can be used for isolated flyback as well as buck
topologies. The device offers a suite of robust protection features to
ensure safe operation under a range of fault conditions.
Version NCL30060B2 is intended for constant voltage (CV)
regulated output drivers where a DC−DC converter or linear regulator
in the second stage controls the current to the LEDs so the output short
circuit protection detector function has been disabled.
Features
•
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•
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Built−In High Voltage Start−up Circuit
Direct Opto−coupler Feedback Connection
Constant On−Time PWM Control
Quasi−Resonant Switching
Low Operating Current (1.6 mA typical)
Source 250 mA / Sink 400 mA Totem Pole Gate Driver
Integrated 12 V (typ) Gate Drive Clamp
Frequency Dithering for Reduced EMI Profile
Enable/Disable Function
Dynamic Self−Supply (DSS) Operation
Operating TJ from −40°C to 105°C
Maximum On Time Protection
Integrated Brown−out
Overvoltage Protection
Cycle−by−Cycle Overcurrent Protection
Output Winding Short−Circuit Protection
Thermal Shutdown
These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
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MARKING
DIAGRAM
8
L0060xx
ALYWG
G
SOIC−7
CASE 751U
1
L0060xx = Specific Device Code
xx
= A, B, B1, B2
A
= Assembly Location
L
= Wafer Lot
Y
= Year
W
= Work Week
G
= Pb−Free Package
(Note: Microdot may be in either location)
PIN CONNECTIONS
FB 1
8
HV
6
VCC
5
DRV
CS/ZCD 2
RT 3
GND
4
(Top View)
ORDERING INFORMATION
See detailed ordering and shipping information on page 14 of
this data sheet.
Typical Applications
• LED Lighting
© Semiconductor Components Industries, LLC, 2016
July, 2016 − Rev. 4
1
Publication Order Number:
NCL30060/D
Neutral
Line
Figure 1. NCL30060 Typical Application Diagram
CFB
RZCD
DZCD
EMI FILTER
RT
DRV
GND
RCS
Vcc
HV
RT
CS
FB
U1
NCL30060
CVcc
DHV
Cin
DVcc
Dclamp
Rsense
M1
Rclamp
U2
CY
4
3
2
1
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2
Cclamp
Cout +
Dout
Ro
RVcc1
DVcc1
CVcc1
RIS
GND
Vcc
FBC
RIS1
ISNS
VSNS
U3
NCP4328A
Rcomp2
Ccomp1
Ccomp2
LED Cathode
RVout2
RVout1
LED Anode
NCL30060
NCL30060
Thermal
Shutdown
Short Circuit Detector
ACTIVE
Open RT Pin
BO_NOK
Ő
TSHDN
Delay
tSHDN(delay)
Integration
Pulse
tint
Central
Logic
UVLO
VCC
blanking
(Fault_OVP)
Counter
Count
Reset
+
−
VDD ACTIVE
−
VDD2
DRV
OVP
Comparator
VOVP
Peak Current
DRV Comparator
LEB
tCS(LEB1)
VCC
Management
Internal
Reference
DRV
+
VCC_OK
HV
Startup
Control
Maximum
Off−Time
Detector
toff(MAX)
VCC(on)/
VCC(off)/
VCC(reset)/
VCC(rUVLO)/
VCC(OVP)
Short
Winding
Comparator
toff1,2 Timer
Counter
−
Brown−out
Detection
Auto−Restart
Fault Control
‘HV Tran
VILIM1
+
Reset
ILIM2
VILIM2
−
DRV
CS/ZCD
LEB
tCS(LEB2)
Count
UVLO
VCC
HV(high)
−
ILIM2, OVP
DRV
Edge
Detector
ZCD
Comparator
+
Disable
Selector
Reset
Re−start
VCC
+
Istart
Selector
VZCD
Edge
Detector
TSHDN
ZCD Blanking
Time
VCC
DRV
Clamp
S
Q
Reset
Dominant
Latch
Q
R
VDD2
Vton(MAX)
FB
PWM DRV
Comparator
Von−time
ACTIVE
IRT
FB Offset
Ramp Modulation
fMOD
DRV
RT Disable
Comparator
+
IRT(disable) * RCS
ton(mod)
Current
Mirror
+
VPRT
−
RCS
RT Enable
Comparator
−
−
ACTIVE
UVLO
Max On−Time
Clamp
On Time
Ramp
Delay
tdisable(blank)/
tenable(blank)
GND
+
Max On Time
Comparator
DRV
ACTIVE
Figure 2. NCL30060 Internal Functional Block Diagram
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3
VRT(enable)
RT
NCL30060
Table 1. NCL30060 PIN FUNCTION DESCRIPTION
Pin No
Pin Name
Pin Description
1
FB
Feedback Input. The FB pin is the control input to the PWM comparator. A voltage level controlled by the
feedback loop on this pin is compared to the internal ramp establishing power switch on time.
2
CS/ZCD
Current sense and zero current detection. The CS input is used to sense the instantaneous switch current in the external power switch during switch on time. A fast−responding high threshold level for short
circuit detection is provided along with a longer blanking time at lower level for overload conditions. During switch off time, this pin monitors the bias winding to detect transformer demagnetization. When
stored energy is depleted the gate drive turns on the power switch initiating the next cycle. This pin also
detects overvoltage conditions through the bias winding. A blanking time prevents false overvoltage triggering due to noise.
3
RT
Maximum on−time adjust. The RT pin establishes the ramp charging current. The PWM comparator establishes the switch on time from the ramp and FB signal. Pulling the RT pin below the disable threshold
forces the controller in the Armed mode where all switching functions cease.
4
GND
Ground. This is the ground reference for the controller. All bypassing and control components should be
connected to the GND pin with a short trace length to minimize noise.
5
DRV
Drive. The high current capability of the totem pole gate drive makes it suitable to directly control high
gate charge power MOSFETs. The driver stage provides both passive and active pull−down circuits
which force the MOSFET gate off when VCC is below normal operating levels.
6
VCC
IC Supply. This is the positive supply of the controller and source for powering external circuits. Internal
bias will be disabled when external power is sufficient to maintain operation.
7
NC
No−connect. This missing pin provides creepage distance.
8
HV
High−voltage input. Monitors input voltage for brown−out detection and power to operate controller.
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4
NCL30060
Table 2. MAXIMUM RATINGS (Notes 1, 2, 3 and 4)
Rating
Symbol
Value
Unit
FB Voltage
VFB
−0.3 to 10
V
FB Current
IFB
±10
mA
CS/ZCD Voltage
VCS/ZCD
−0.9 to 12.4
V
CS/ZCD Current
ICS/ZCD
−2 / +5
mA
VRT
−0.3 to 5
V
RT Voltage
RT Current
DRV Voltage (Note 2)
DRV Sink Current
DRV Source Current
Supply Voltage
Supply Voltage Rate of Change
IRT
±10
mA
VDRV
−0.3 to VDRV(high)
V
IDRV(sink)
400
mA
IDRV(source)
250
mA
VCC
−0.3 to 30
V
dVCC/dt
1
V/ms
Supply Current
ICC
20
mA
HV Voltage
VHV
−0.3 to 700
V
HV Current
IHV
20
mA
RqJA
125
_C/W
Thermal Resistance, Junction to Ambient 1 Oz Cu Printed Circuit Copper Clad)
ESD Capability
Human Body Model per JEDEC Standard JESD22−A114E. (Note 5)
Machine Model per JEDEC Standard JESD22−A114E.
Charge Device Model per JEDEC Standard JESD22−C101E.
V
5000
200
1500
TJ
−40 to 105
°C
Maximum Junction Temperature
TJMax
150
°C
Storage Temperature Range
TSTG
−60 to 150
°C
TL
300
°C
Operating Temperature Range While Biased
Lead Temperature (Soldering, 10 s)
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.
1. VCS/ZCD(MAX) is the maximum voltage of the pin shown in the electrical table. When the voltage on this pin exceeds 7.4 V, the pin sinks a
current equal to [(VCS/ZCD − 7.4 V) / 1 kW]. A VCS/ZCD of 9 V generates a sink current of approximately 1.6 mA.
2. Maximum driver voltage is limited by the driver clamp voltage, VDRV(high), when VCC exceeds the driver clamp voltage. Otherwise, the
maximum driver voltage is VCC.
3. This device contains Latch−Up protection and has been tested per JEDEC Standard JESD78D, Class I and exceeds ±100 mA.
4. Low Conductivity Board. As mounted on 80 x 100 x 1.5 mm FR4 substrate with a single layer of 50 mm2 of 2 oz copper trances and heat
spreading area. As specified for a JEDEC51−1 conductivity test PCB. Test conditions were under natural convection of zero air flow.
5. Pin 8 HV pin is ESD rated to 1200 V.
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NCL30060
ELECTRICAL CHARACTERISTICS (VCC = 14 V, VHV = 120 V, VFB = 4 V, VCS/ZCD = 0 V, CDRV = 1 nF, RT = 20 kW, for typical values
TJ = 25_C, for min/max values, TJ is – 40_C to 105_C, unless otherwise noted)
Characteristic
Test Conditions
Symbol
Min
Typ
Max
Unit
1 V/ms, VCC increasing
1 V/ms, VCC decreasing
VCC(on) − VCC(MIN)
VCC decreasing
1 V/ms, VCC(min) − VCC(UVLO)
VCC decreasing
VCC increasing
VCC(on)
VCC(MIN)
VCC(HYS1)
VCC(UVLO)
VCC(HYS2)
VCC(reset)
VCC(inhibit)
11.75
10.7
0.9
8.2
2.0
4.5
0.35
12.5
11.5
–
8.8
–
5.5
0.7
13.75
12.8
–
9.4
–
7.5
0.95
VRT = 0 V
CDRV = open
CDRV = 1nF
ICC1
ICC2
ICC4
ICC5
140
300
800
1490
190
335
870
1600
240
450
975
1700
Istart1
Istart2
Istart3
0.31
9
3.5
0.77
14
5.25
1.23
19
7.00
mA
VCC(OVP)
27
28
29
V
tdelay(VCC_OVP)
15
30
50
ms
V HV = 400 V, VCC = VCC(on)
to VCC(MAX)
IHV(off)
–
24
30
mA
Istart2 = 1 mA
VHV(MIN)
–
–
40
V
Istart3 = 5.25 mA
VHV(tran)
160
175
190
V
VDRV from 10 to 90% of
VDRV
tPDRV(rise)
−
80
180
−
40
80
STARTUP AND SUPPLY CIRCUITS
Supply Voltage
Startup Threshold
Minimum Operating Voltage
Operating Hysteresis
Undervoltage Lockout
Hysteresis Between VCC(MIN) and VCC(UVLO)
Internal Latch/Logic Reset Level
Transition from Istart1 to Istart2
Supply Current
In Fault Mode
In Disable Modes
Active Mode Without CDRV, fSW = 60 kHz
Active Mode With CDRV, fSW = 60 kHz
Startup Current
V
mA
VCC = 0 V to Vinhibit
VHV = 400V
VCC Overvoltage Protection Threshold
VCC Overvoltage Protection Delay
Startup Circuit Off−State Leakage Current
Minimum Startup Voltage
Startup Current Transition Voltage Threshold
GATE DRIVE
Rise Time (10−90%)
Fall Time (90−10%)
Current Capability
Source
Sink
High State Voltage
Low State Voltage
ns
VDRV from 90 to 10% of
VDRV
tPDRV(fall)
ns
VDRV = 2 V
VDRV = 10 V
IDRV(SRC)
IDRV(SNK)
–
–
250
400
–
–
VCC = VCC(UVLO) + 0.2 V,
RDRV = 10 kW
VDRV(highuvlo)
−
−
0.25
V
VCC = VCC(OVP) − 0.5 V ,
RDRV = 10 kW
VDRV(high)
10
12
14
V
IDRV = 100mA
VDRV(low)
–
–
0.25
V
VFB = open
VFB(open)
6.0
6.3
6.6
V
VFB decreasing
VFB(offset)
0.60
0.70
0.80
V
RFB(bias)
20
25.8
29.6
kW
mA
FEEDBACK
Feedback Open Voltage
Minimum FB Voltage to Generate Drive Pulses
Feedback Bias Resistor
CONSTANT ON TIME GENERATOR
On Time
RT = 20 kW, VFB = VFB(open)
RT = 10 kW, VFB = VFB(open)
RT = 80 kW, VFB = VFB(open)
RT = 80 kW, VFB = 4.45 V
RT = 80 kW, VFB = 3.2 V
ton1
ton2
ton3
ton4
ton5
4.75
2.37
18.4
13.6
9.0
5.0
2.50
19.5
14.5
9.56
5.25
2.63
20.7
15.5
10.1
ms
Maximum On Time
RT = 110 kW to open, VFB =
VFB(open)
ton(MAX)
22.0
27.5
33.0
ms
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.
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NCL30060
ELECTRICAL CHARACTERISTICS (VCC = 14 V, VHV = 120 V, VFB = 4 V, VCS/ZCD = 0 V, CDRV = 1 nF, RT = 20 kW, for typical values
TJ = 25_C, for min/max values, TJ is – 40_C to 105_C, unless otherwise noted)
Characteristic
Test Conditions
Symbol
Min
Typ
Max
Unit
VFB increasing
VFB(tonMAX)
5.415
5.70
5.985
V
VRT(REG)
–
2.0
–
V
CONSTANT ON TIME GENERATOR
Maximum On−Time Feedback Voltage
RT Pin Regulation Voltage
On−Time Modulation Frequency
On Time Modulation
fMOD
254
292
325
Hz
ton(MOD)
±4
±6
±8
%
DISABLE FUNCTION
RT Disable Current Threshold
IRT Decreasing
IRT(disable)
250
325
400
mA
RT Enable Threshold
VRT increasing
VRT(enable)
380
400
420
mV
IRT(dis)
45
50
55
mA
tdisable(blank)
6.8
8
9.8
ms
RT Pull−Up Current In Disable Mode
Disable Blanking
IRT increasing or VDisable
decreasing
ZERO CURRENT DETECTION
ZCD Arming Threshold
VCS/ZCD Increasing
VZCD(ARM)
225
250
275
mV
ZCD Trigger Threshold
VCS/ZCD Decreasing
VZCD(TRIG)
35
55
90
mV
tARM(blank)
1.7
2.05
2.35
ms
tZCD(PROP)
–
150
170
ns
−
−0.9
12.4
−0.7
−
0
ZCD Arming Blanking Duration
ZCD Propagation Delay
Input Voltage Excursion
Upper Clamp
Negative Clamp
VCS/ZCD stepping from 2.0 V
to 0 V,
dV/dt = 20 V/ms,
VCS/ZCD = VZCD(TRIG) to
VDRV = 10%
V
VCC = 14V, ICS/ZCD = 5 mA VCS/ZCD(MAX)
VCC = 14V, ICS/ZCD = −2 mA VCS/ZCD(MIN)
CS/ZCD Open Voltage
VZCD(open)
6.5
–
–
V
Pull−up Current Source
ICS/ZCD
0.7
1.0
1.3
mA
toff1
toff2
100
1000
200
1250
300
1700
ms
Between VZCD(rising) and
VZCD(falling) to DRV
tSYNC
–
70
200
ns
TJ = 25_C
TJ = −40_C to 125_C
VILIM1
242.5
238
250
250
257.5
262
mV
Propagation Delay
Step VCS/ZCD 0 V to VILIM1 +
0.1 V to DRV falling edge,
tILIM1
−
100
200
ns
Leading Edge Blanking Duration
Step VCS/ZCD 0 V to VILIM1 +
0.1 V to DRV falling edge,
tCS(LEB1)
250
325
400
ns
VILIM2
475
500
525
mV
Timeout After Last Demagnetization Detection
VCS/ZCD > VILIM2
Minimum ZCD Pulse Width
CURRENT SENSE
Current Sense Voltage Threshold
Abnormal Overcurrent Fault Threshold
Fault Propagation Delay
Step VCS/ZCD 0 V to VILIM2 +
0.1 V to DRV falling edge,
tILIM2
–
125
175
ns
Fault Leading Edge Blanking Duration
Step VCS/ZCD 0 V to VILIM2 +
0.1 V to DRV falling edge,
tCS(LEB2)
90
120
150
ns
Leading Edge Blanking Duration Ratio
tLEB(LEB2)/tLEB1
tLEB(ratio)
–
0.37
–
−
nILIM2
–
4
–
Number of Consecutive Abnormal Current Events to
Enter Fault Mode (Latch mode available on
customer request)
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.
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NCL30060
ELECTRICAL CHARACTERISTICS (VCC = 14 V, VHV = 120 V, VFB = 4 V, VCS/ZCD = 0 V, CDRV = 1 nF, RT = 20 kW, for typical values
TJ = 25_C, for min/max values, TJ is – 40_C to 105_C, unless otherwise noted)
Characteristic
Test Conditions
Symbol
Min
Typ
Max
Unit
43
50
55
ms
ms
OUTPUT SHORT CIRCUIT AND OVERVOLTAGE PROTECTION
Output Short Off−Time Detector Threshold (Note 6)
Detected during DRV low
toff(OS)
Output Short Detection Integration Weighting Ratio
(Note 6)
NINTratio(OS)=
Charging speed(Output
Short detected)
/ Discharging speed (normal
operation)
NINTratio(OS)
Output Short Detection Integration Time for
Continuous Integration pulses (Note 6)
20
tINTCON(OS)
36.7
40
45.7
DRV is low
VOVP
5.8
6.0
6.2
V
VCS/ZCD = 0 V to 7 V ramp,
dV/dt = 1 V/ms, VCS/ZCD =
VOVP to
DRV low
tOVP(PROP)
–
–
2.5
ms
tOVP(blank)
1.5
2.0
2.5
ms
nOVP
–
4
–
tautorecovery
0.8
1.0
1.2
s
System Startup Threshold
VBO(start)
102
111
120
V
System Shutdown Threshold
VBO(stop)
88
96
104
V
tBO(stop)
43
54
65
ms
Overvoltage Threshold
Overvoltage Propagation Delay
Overvoltage Blanking
Number of Consecutive Overvoltage Events to
Enter Fault Mode Mode (Latch mode available on
customer request)
Auto−recovery Timer Duration
BROWN−OUT PROTECTION (does not apply to B1 option)
Brown−out Detection Blanking Time
VHV decreasing, delay from
VBO(stop) to drive disable
THERMAL PROTECTION
Thermal Shutdown
Temperature increasing
TSHDN
−
160
−
_C
Thermal Shutdown Hysteresis
Temperature decreasing
TSHDN(HYS)
−
50
−
_C
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.
6. Parameter does not apply to B2 option.
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NCL30060
DETAILED OPERATING DESCRIPTION
I CC(gate charge) + f @ Q G
HIGH VOLTAGE STARTUP CIRCUIT
The NCL30060 integrates a 700 V startup regulator
eliminating the need of external startup components. The
startup regulator consists of a constant current source that
supplies current from the high voltage input terminal (HV)
to the supply capacitor on the VCC pin (CCC). The startup
circuit current (Istart2) and (Istart3) are disabled if the VCC
pin is below VCC(inhibit). In this condition, the startup current
is reduced to Istart1, typically 0.77 mA. In addition, this
regulator reduces no load power and increases the system
efficiency as it uses negligible power in the normal operation
mode.
After VCC pin is higher than VCC(inhibit) threshold, the
startup circuit uses Istart3 to charge the VCC capacitor during
the initial charging. Istart3 has a typical value of 5.25 mA.
Once CCC is charged to the startup threshold, VCC(on),
typically 12.5 V, the startup regulator is disabled and the
controller is enabled. The initial charging on VCC capacitor
is done. The controller is then biased by the VCC capacitor.
(eq. 1)
where f is the operating frequency and QG is the gate charge
of the external MOSFETs. The additional gate charge
current should not exceed the startup circuit. Otherwise,
VCC will not charge to VCC(on) and may stay at an
undetermined voltage while dissipating excessive power.
The controller and the startup circuit are disabled if the
junction temperature of the device exceeds the thermal
shutdown threshold, TSHDN, typically 160_C. The
controller is disabled if VCC falls below the undervoltage
lockout (UVLO) threshold, VCC(UVLO), typically 8.8 V. A
noise filter, tUVLO, 25 ms maximum, blanks the UVLO fault
before disabling the controller.
FEEDBACK INPUT
A signal proportional to the output error is applied to the
FB pin by means of an optocoupler or other means such as
an Op Amp. The PWM Comparator compares the feedback
or error signal to a level shifted voltage ramp to control the
power switch on−time. The feedback voltage is directly
proportional to the output power. An internal pull up resistor,
RFB, drives this pin to provide more linear response from the
optocoupler transistor. The voltage reference biasing RFB is
typically 6.3 V .
The minimum on−time, ton(MIN), is determined by the
propagation delay of the PWM Comparator and control
logic. It is limited below 200 ns. The minimum on−time is
achieved when VFB is right on the voltage offset of the
On−time Ramp, VFB(offset). A VFB below VFB(offset) results
in no drive pulses or “zero” on−time.
The maximum on−time is limited by the Maximum
On−time comparator. The comparator is enabled once the
feedback voltage, VFB, exceeds VFB(tonMAX). This
establishes the point where the LED driver transitions from
constant current feedback (if so configured) to primary
power control.
Figure 3. Initial Charging of VCC and Normal DSS
The startup regulator is enabled once VCC falls below its
minimum operating threshold, VCC(MIN), typically 11.5 V.
The driver continues operation while VCC is charged by the
startup circuit. This operating mode is known as dynamic
self supply or DSS. During normal DSS operation, the
startup circuit uses Istart2 to charge the VCC capacitor when
the line voltage is below VHV(tran), and the startup circuit
uses Istart3 when the line voltage is higher than VHV(tran).
VHV(tran) has a typical value of 175 V. Figure 3 shows the
initial charging of VCC capacitor and normal DSS.
The startup circuit continues to charge VCC until the
convertor bias winding is able to provide power to the VCC
capacitor. As long as the bias winding can maintain the VCC
voltage higher than VCC(MIN), the startup circuit will not be
enabled. The startup circuit enters DSS mode if the VCC
voltage is lower than VCC(MIN).
The increase in current consumption due to external gate
charge is calculated using Equation 1.
MAXIMUM ON−TIME
The PWM Comparator controls the on−time by
comparing an internal voltage ramp, Von−time, to the
feedback voltage. The internal ramp is generated by
charging an internal capacitor with a fixed current source.
The slope of the ramp is adjusted by the user using an
external timing resistor, RT, between the RT and GND pins.
The architecture of the on−time control circuitry is shown in
Figure 4.
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NCL30060
VCC
Clamp
S
Q
Reset
Dominant
Latch
Q
R
PWM
Max On Time
Comparator
DRV
DRV
ACTIVE
GND
UVLO
Max On−Time
Clamp
Comparator
VDD2
FB Offset
Vton(MAX)
Von−time
ACTIVE
On Time
DRV
Ramp
ton(mod)
RCS
IRT(disable) * RCS
RT Disable
Comparator
RT
Mirror
+
VPRT
−
+
Delay
tdisable(blank)/
tenable(blank)
Current
fMOD
RT Enable
Comparator
+
FB
−
ACTIVE
IRT
Ramp Modulation
VRT(enable)
−
Figure 4. On−Time Control Architecture
The on−time is internally modulated to reduce the EMI
signature of the controller. The modulation is accomplished
by modulating the charge current using an internal triangle
wave oscillator. The charge current is adjusted ±6% from the
nominal value. The EMI signature of the controller is spread
over a wide range of frequencies eliminating high peaks
during an average reading.
The absolute maximum on−time determines the
maximum power of the system. The NCL30060 accurately
controls the maximum on−time of the system by the Max
On−time Clamp circuits. It ensures that On−time can’t
exceed ton(MAX), typically 27.5 ms, when the RT resister
value is above 110 kW. There is also a fixed voltage
reference, Vton(MAX), which defines the maximum effective
VFB voltage. Given a certain RT value between 10 kW and
110 kW, the Maximum On−time Comparator controls the
on−time when primary side regulation is required. This
could occur during an overload condition or during startup
when the feedback signal is not present. The relationship
between RT and ton(MAX) is given by Equation 2 and
Figure 5.
t on(MAX) + 0.25 @ R T
Figure 5. Maximum On−Time vs RT
The RT pin has a threshold output current of IRT(disable)
which has a maximum value of 400 mA. The maximum
on−time is limited to 27.5 ms if the pin is left open or the Rt
is higher than 110 kW. If the resistance between RT pin and
GND is small enough to make the RT pin current higher than
IRT(disable), the device is disabled after the blanking delay
tdisable(blank) and the RT pin output current is switched to
(eq. 2)
Where ton(MAX) is in ms and RT is in kW.
www.onsemi.com
10
NCL30060
IRT(dis) which has 50 mA typical value. After the device is
disabled, the integrated HV source maintains VCC above
VCC(min). The IC is activated when the voltage of the RT pin
is higher than the VRT(enable), which has typical value of
400 mV. And the RT pin output current is switched back to
normal operation, and the RT voltage is regulated to
VRT(REG),which has a typical value of 2 V.
The timing resistor should be placed as close as possible
to the RT and GND pins with short trace lengths. Care should
be taken to keep switching nodes (high dv/dt) away from RT
to reduce noise pickup.
CURRENT SENSE, ZERO CURRENT AND
OVERVOLTAGE DETECTION
The NCL30060 uses a novel architecture combining the
current sense, the zero current detector (ZCD), output
overvoltage and shorted output detector functions in a single
terminal. Figure 6 shows the circuit schematic of the current
sense and ZCD detectors.
Peak Current
DRV Comparator
LEB
tCS(LEB1)
VCC
+
−
Short
Winding
Comparator
Counter
VILIM1
CS/ZCD
LEB
tCS(LEB2)
Count
+
Reset
VILIM2
−
DRV
ILIM2
toff1,2 Timer
UVLO
VCC
ZCD
Comparator
Disable
ILIM2, OVP
DRV
Edge
VZCD
HV(high)
−
Reset
Re−start
+
Selector
Detector
Edge
Detector
TSHDN
VCC
ZCD Blanking
Time
DRV
Clamp
S
Q
Reset
Dominant
Latch
Q
R
DRV
ACTIVE
UVLO
GND
Figure 6. Current Sense and ZCD Detectors Schematic
CURRENT SENSE
The NCL30060 protects against this fault by adding an
additional comparator, Short Circuit Comparator. The
current sense signal is blanked with a shorter LEB duration,
tCS(LEB2), typically 125 ns, before applying it to the Short
Circuit Comparator. The voltage threshold of the
comparator, VILIM2, typically 0.5 V, is set twice the level of
VILIM1, to avoid interference with normal operation. Four
consecutive faults detected by the Short Circuit Comparator
causes the controller to enter a fault mode. The NCL30060B
will auto−recover from the fault state if the short is removed.
The count to 4 provides noise immunity during surge testing.
The counter is reset each time a DRV pulse occurs without
activating the Short Circuit Comparator.
The watchdog timer duration (toff2) is increased to
1.25 ms independent of the PFC ZCD state.
The Switch current is sensed across a sense resistor,
Rsense, and the resulting voltage ramp is applied to the
CS/ZCD pin. The current signal is blanked by a leading edge
blanking (LEB) circuit. The blanking period eliminates the
leading edge spike and high frequency noise during the
switch turn−on event. The LEB period, tCS(LEB1), is
typically 325 ns. The Current Limit Comparator disables the
driver once the current sense signal exceeds the current
sense reference, VILIM1, typically 0.25 V. The next
switching cycle is initiated by the ZCD or watchdog timer.
A severe overload fault like a secondary side winding
short circuit causes the switch current to increase very
rapidly during the on−time. The current sense signal
significantly exceeds VILIM1. But, because the current sense
signal is blanked by the LEB circuit during the switch turn
on, the current could damage the system.
www.onsemi.com
11
NCL30060
Figure 7. Secondary Side Winding Short−Circuit Waveforms
Figure 7 shows simulation results for an output winding
short. The simulation waveforms are described below:
♦ DRV/V is gate drive signal for the PFC switch.
♦ VCS/V is the signal on the CS/ZCD pin.
♦ ZCDW/V is the voltage across the ZCD winding.
♦ VHV1/V is the voltage on the HV pin.
The converter is operating normally and a momentary
fault is applied at 24 ms. Once the fault is applied, the
watchdog timer duration increases to toff2. The fault is
removed after two faults overcurrent events are detected.
The fault is re−applied at 35 ms. After four consecutive
overcurrent conditions are detected, the fault signal goes
high.
Rzcd
Dzcd
Switch
DRV
CS/ZCD
Rcs
Rsense
Figure 8. ZCD Winding Implementation
ZERO CURRENT DETECTION
The off−time in a CrM topology varies with the
instantaneous line voltage and it is adjusted every cycle to
allow the inductor current to reach zero before the next
switch cycle begins. The inductor is demagnetized once its
current reaches zero. Once the inductor is demagnetized the
drain voltage of the switch begins to fall. The inductor
demagnetization is detected by sensing the voltage across
the inductor using an auxiliary winding. This winding is
commonly known as a zero crossing detector (ZCD)
winding. This winding provides a scaled version of the drain
voltage. Figure 8 shows the ZCD winding arrangement.
The ZCD voltage, VCS/ZCD, is positive while the Switch
is off and current flows on the secondary side. VCS/ZCD
drops to and rings around zero volts once the transformer is
demagnetized. The next switch cycle commences once a
negative going transition is detected in the CS/ZCD pin. A
positive transition (corresponding to the switch turn off)
arms the ZCD detector to prevent false triggering. The
arming of the ZCD detector, VZCD(ARM), is typically
250 mV (VCS/ZCD increasing). The trigger threshold,
VZCD(TRIG), is typically 55 mV (VCS/ZCD decreasing).
www.onsemi.com
12
NCL30060
controller shutting down after an overvoltage condition is
detected.
The NCL30060 incorporates a minimum off−time delay,
tARM(blank).,typically 2.0 ms . This delay blanks the ringing
which may be present on the bias winding during start up or
if the output of the converter is shorted. The next DRV pulse
is initiated once tARM(blank) expires if a ZCD transition is
detected prior to the delay expiring. Otherwise, it will
initiate on the ZCD transition after tARM(blank) expires. In
the absence of a ZCD transition, the watchdog timer initiates
the next drive pulse.
The CS/ZCD pin is internally clamped to VCC thru an
internal diode. A 7.4 V Zener diode with a 1 kW resistor to
GND also clamp the pin. A resistor in series with the
CS/ZCD pin is required to limit the current into pin. The
Zener diode also prevents the voltage from going below
ground. Figure 9 shows typical ZCD waveforms.
Figure 10. Overvoltage Detection Operating
Waveforms
OUTPUT SHORT CIRCUIT DETECTION
When the converter is operating with low output voltage,
the off−time is extended in CrM operation. In Figure 11 of
the output short detection function block, the maximum
off−time detector signals when the off time is longer than
50 ms. This 50 ms off time detection triggers a 150 ms pulse
to feed the integrator. The integrator has a weighted
integration feature, which makes the charging 20 times
faster than the discharging. A continuous stream of 150 ms
pulses will reach the integrator threshold in 40ms. Periods
of time without triggering the 150 ms timer will extend the
time to reach the threshold. The integrator discharges as the
relative number of 150 ms pulses over time decreases.
Figure 9. ZCD Winding Waveforms
During startup there are no ZCD transitions to set the
PWM Latch and generate a DRV pulse. A watchdog timer,
toff1, starts the drive pulses in the absence of ZCD
transitions. Its duration is typically 200 ms. The timer is also
useful during startup and while operating at light load
because the amplitude of the ZCD signal may be very small
to cross the ZCD thresholds. The watchdog timer is reset at
the beginning of a drive pulse. It is disabled if the CS/ZCD
pin is above the ZCD arming threshold.
The watchdog timer duration increases to toff2, typically
1.25 ms, when a VILIM2 fault is detected.
OVERVOLTAGE PROTECTION
Figure 11. Output Short−Circuit Detector
Output overvoltage protection (OVP) is provided by
monitoring the CS/ZCD pin during the off−time. A
dedicated comparator compares the voltage on CS/ZCD pin
to an internal reference, VOVP, typically 6 V. If 4 consecutive
OVP events are detected the controller enters a fault mode.
A 2 ms blanking delay, tOVP(blank), blanks the signal CS/ZCD
signal after the drive turns off to blank ringing generated by
system parasitics. The blanking provides protection during
power up and steady state operation. Figure 10 shows the
When the threshold is reached, the system will determine
there is an output short event. The system enters into fault
mode. The NCL30060B will try to auto−recover after a 1 sec
typical delay. This minimizes system power consumption
due to the output short event. Figure 12 shows auto−restart
operating waveforms.
www.onsemi.com
13
NCL30060
by crossing the shutdown threshold again. Such cycling on
and off near the brown out threshold would result in LED
flicker. Allowing the energy to discharge naturally near the
zero crossing provides a clean brown out shutdown.
MOSFET DRIVER
The NCL30060 maximum supply voltage, VCC(OVP), is
28 V. Typical high voltage MOSFETs have a maximum gate
voltage rating of 20 V. The driver incorporates an active
voltage clamp to limit the gate voltage on the external
MOSFET. The voltage clamp, VDRV(high), is typically 12 V
with a maximum limit of 14 V.
Figure 12. Output Short Detection and Protection
Waveform
Version NCL30060B2 is intended for constant voltage
(CV) regulated output drivers where a DC−DC converter or
linear regulator in the second stage controls the current to the
LEDs so the output short circuit protection detector function
has been disabled.
AUTO−RECOVERY
The controller is disabled and enters a fault mode if VCC
drops below VCC(UVLO) or a non−latching fault is detected.
The controller auto−restarts after the auto−recovery timer
tautorecovery, expires, typically 1 s.
BROWN OUT DETECTION
THERMAL SHUTDOWN
The NCL30060 includes brown out protection providing
a defined shutdown for low input voltage. This feature is
enabled after a VCC reset event and does not allow the
controller to enter Active mode until the input voltage is
above the startup threshold, typically 111 V.
If the input voltage remains below the system shutdown
threshold, typically 96 V, longer than the brown out
detection blanking time, typically 54 ms, a shutdown flag is
set. Gate drive pulses will continue to be issued until the
input voltage is near the ac line voltage zero crossing. When
a zero crossing is detected and the flag is set, gate drive
pulses cease thereby stopping power delivery to the LED
load. The brown out flag remains set and switching is
suspended until the input voltage rises above the startup
threshold.
Delaying termination of gate drive pulses until the zero
crossing ensures the system is at a low power state before
shutting down. This approach avoids a situation where
energy stored in the input filter may artificially force the
sensed voltage to cross the startup threshold if switching is
abruptly terminated. A false startup level would be followed
An internal thermal shutdown circuit monitors the
junction temperature of the IC. The controller including the
startup circuit is disabled if the junction temperature exceeds
the thermal shutdown threshold, TSHDN, typically 150 _C.
Once a thermal shutdown condition is validated, the startup
circuit is disabled. The startup circuit is enabled once VCC
falls below VCC(reset), charging VCC up to VCC(on). The
controller remains disabled if the thermal shutdown is
present upon reaching VCC(on). The controller restarts at the
next VCC(on) once the IC temperature drops below TSHDN by
the thermal shutdown hysteresis, TSHDN(HYS), typically
40_C.
LAYOUT CONSIDERATIONS
The GND pin is the reference point for the controller.
Unless specified otherwise, all measurements are made
relative to this pin. Both power and control circuits use this
reference. It is recommended to have short traces between
this pin and control components to reduce parasitic
inductance.
ORDERING INFORMATION
Ordering Part No.
OCP
Brown Out
Output Short Detection
NCL30060ADR2G*
Latched
Enabled
Enabled
NCL30060BDR2G
Auto−recoverable
Enabled
Enabled
NCL30060B1DR2G*
Auto−recoverable
Disabled
Enabled
NCL30060B2DR2G
Auto−recoverable
Enabled
Disabled
Package
Shipping†
SOIC−7
(Pb−Free)
2500 / 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.
*Version available only by customer request.
www.onsemi.com
14
NCL30060
PACKAGE DIMENSIONS
SOIC−7
CASE 751U
ISSUE E
−A−
8
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION A AND B ARE DATUMS AND T
IS A DATUM SURFACE.
4. DIMENSION A AND B DO NOT INCLUDE
MOLD PROTRUSION.
5. MAXIMUM MOLD PROTRUSION 0.15 (0.006)
PER SIDE.
5
−B− S
0.25 (0.010)
B
M
M
1
4
DIM
A
B
C
D
G
H
J
K
M
N
S
G
C
R
X 45 _
J
−T−
SEATING
PLANE
H
0.25 (0.010)
K
M
D 7 PL
M
T B
S
A
MILLIMETERS
MIN
MAX
4.80
5.00
3.80
4.00
1.35
1.75
0.33
0.51
1.27 BSC
0.10
0.25
0.19
0.25
0.40
1.27
0_
8_
0.25
0.50
5.80
6.20
INCHES
MIN MAX
0.189 0.197
0.150 0.157
0.053 0.069
0.013 0.020
0.050 BSC
0.004 0.010
0.007 0.010
0.016 0.050
0_
8_
0.010 0.020
0.228 0.244
S
SOLDERING FOOTPRINT*
1.52
0.060
7.0
0.275
4.0
0.155
0.6
0.024
1.270
0.050
SCALE 6:1
mm Ǔ
ǒinches
*For additional information on our Pb−Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
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NCL30060/D