SM8205

SM8205
High-Power LED Driver with Integrated PWM Dimming MOSFET Driver
GENERAL DESCRIPTION
FEATURES
The SM8205 is a current mode control wide-input
voltage (8V to 48V) LED driver IC specifically designed
to power one or multi-strings of high power LEDs. The
10V gate driver allow the use of standard level MOSFET
. The low voltage 5.0V VCC is used to power the internal
logic and also acts as a reference voltage to set the
current level. An external resistor sets the adjustable
switching frequency of the SM8205. The switching
frequency can be between 100KHz and 1MHz to
optimize efficiency, performance or external component
size. This controller uses a peak-current control scheme
(with programmable slope compensation), and includes
an internal transconductance amplifier to control the
output current in closed loop, enabling high output
current accuracy. Programmable MOSFET current limit
enables current limiting during input under-voltage and
output overload conditions. An internal 8V~48V linear
regulator powers the IC, elimination the need for a
separate power supply for the IC. The SM8205 provides
a TTL compatible PWM dimming input that can accept
an external control signal with a duty ratio of 0~100%
and frequency of up to a few kilohertz. The SM8205 also
provides a FAULT output which can be used to
disconnect the LEDs in case of a fault condition, using
an external disconnect N-channel MOSFET. The
SM8205 also offer the following protection functions:
LED open protection (OVP), LED short-circuit protection
(SCP), Junction over-temperature shutdown and input
under voltage lockout (UVLO).
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Wide input operating voltage range from 8V to 48V
Internal 2% reference voltage
Integrated PWM dimming N-channel MOSFET driver
Dimming ratio: 1000:1
100KHz to 1MHz programmable high-frequency
operation
Programmable slope compensation
Input under-voltage protection
LED short-circuit protection (SCP)
LED open-voltage protection (OVP)
Junction over-temperature shutdown protection
Drivers LEDs in Boost, Buck-Boost, SEPIC Topology
Cycle-by-cycle current limit
Soft start
Providing SOP-16 Package
APPLICATIONS
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Single-string LED LCD backlighting
High power LED drivers
DC/DC Boost / Buck-Boost converter
Automotive or Industrial
TYPICAL APPLICATION CIRCUIT
L1
D1
Vin
8V to 48V
Cout
CIN
CCC
1
2
RT
RL1
4
RL2
Ccomp Rcomp
RR1
RR2
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3
5
6
7
8
VCC
VIN
SS
VDD
RT
GATE
CLIM
CS
PWMD
FAULT
COMP
SC
IREF
FDBK
GND
OVP
1
ROVP1
16
15
CDD
ROVP2
14
12
Q1
Rsc
13
11
9
Rcs
Q2
RSLOPE
Rsn
10
Rev. 2.0 @ 2011/10
SM8205
PIN ASSIGNMENTS
ORDERING INFORMATION
Part Number
VCC
1
16
VIN
SS
2
15
VDD
RT
3
14
GATE
CLIM
4
13
FAULT
PWMD
5
12
CS
COMP
6
11
SC
IREF
7
10
OVP
GND
8
9
FDBK
SM8205SL
Marking
SM8205SL
△xxxxxx
Tube
50
Note: The letter “S” is marked for SOP package, and Letter “L” is
marked for Lead Free parts.
SOP-16 (Top View)
PIN DESCRIPTIONS
Pin No.
Name
1
VCC
2
SS
3
RT
4
CLIM
5
PWMD
6
COMP
7
IREF
8
GND
9
FDBK
10
OVP
11
SC
12
CS
13
FAULT
14
GATE
15
VDD
16
VIN
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Description
5V Low-dropout voltage regulator. Bypass to GND with at least a 4.7uF low-ESR ceramic
capacitor. It provides 2% accurate reference voltage to external IREF and CLIM terminal use for
setting control loop reference.
Soft-start time programming pin. Connect capacitor from SS pin to GND to program converter
soft-start time.
Connect a resistor from RT to GND to program the switching frequency.
This pin provides a programmable input current limit for the converter. The current limit can be set
by using a resistor divider from the VCC pin, soft-start can also be provided using this pin.
PWM dimming input. High level is normal operation, when is pulled to GND or left open, switching
of the SM8205 is disabled.
Error-amplifier output. Connect an RC network from COMP to GND for stable operation.
The voltage at this pin sets the output current level. The current reference can be set using a
resistor divider from VCC pin.
Ground return for all circuit.
LED current sense input. Connect a sense resistor from LED strings to GND to regulate LED
output current.
Over-voltage protection sense input. When this pin voltage exceeds 1.2V, the GATE output of the
SM8205 is turned off and FAULT goes low. The IC will turn on again until input power is recycled.
Slope compensation for current sense. A resistor between SC and GND will program the slope
compensation.
Current sense positive input. Connected to external current sense resistor which in turn is
connected to the source of the external power N-MOSFET as well as an external slope
compensation resistor.
External dimming MOSFET gate driver. This pin is pulled to Ground when there is an output short
circuit or output over voltage fault conditions, and then disconnect the load from voltage source.
Output gate driver pin to drive an external N-channel power MOSFET.
This pin is a regulated 10V supply for two gate driver (GATE and FAULT), It must be bypassed
with a low-ESR ceramic capacitor at least 1.0uF to GND.
Power supply input pin. Voltage input range from 8V to 46V, place a bypass capacitor 1uF~10uF
to ground as close to the device as possible in the circuit board layout.
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Rev. 2.0 @ 2011/10
SM8205
ABSOLUTE MAXIMUM RATINGS
Parameter
Rating
Units
Vin to GND
50
V
VDD to GND
11
V
VCC to GND
5.5
V
GATE , FAULT to GND
11
V
All other pins to GND
5.5
V
Junction To Ambient Thermal Impedance (θJA)
102
℃/W
Junction Temperature
150
℃
Operating Junction Temperature Range
-40 ~ +125
℃
Storage Temperature Range
-65 ~ +150
℃
260
℃
Lead Temperature (Soldering,10sec)
Stresses beyond those listed under“Absolute Maximum Ratings"may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicates in the
operational sections of the specifications is not implied. Exposure to maximum rating conditions for extended periods may
affect device reliability.
RECOMMENDED OPERATING CONDITIONS
Parameter
Symbol
Min
Max
Units
Input Voltage
VIN
8
48
V
Operating Frequency
FOSC
100
1000
KHz
TA
-20
85
℃
Operating Ambient Temperature
ELECTRICAL CHARACTERISTICS
The typically testing values are at VIN=12V, TA=25℃,Unless otherwise noted.
Symbol
Parameter
Min
Typ
Max
Units
Conditions
Input
VIN
Input DC supply voltage range
8
-
48
V
Input to VIN pin voltage
IQ
Quiescent current
-
1.9
2.2
mA
PWMD=0, No switching
9
10
11
Internal Regulator
V
12V ≤ VIN ≤ 48V
VDD
Internally regulated voltage for Gate driver
VIN-1
-
-
UVLO
VDD under-voltage Lockout threshold
6.8
-
7.4
V
VDD rising
ΔUVLO
VDD under-voltage Lockout hysteresis
-
500
-
mV
VDD falling
4.90
5.00
5.10
V
8V ≤ VIN ≤ 11V
Reference
VCC
VCC pin voltage
VCC(Line)
Line regulation of the VCC voltage
0
-
20
mV
VCC pin connected a 10uF
Capacitor to GND, ICC=0,
PWMD=0
VIN=8~48V, PWMD=0
VCC(Load)
Load regulation of the VCC voltage
0
-
15
mV
ICC=0~3mA, PWMD=0
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Rev. 2.0 @ 2011/10
SM8205
ELECTRICAL CHARACTERISTICS (continued)
The typically testing values are at VIN=12V, TA=25℃,Unless otherwise noted.
Symbol
Parameter
Min
Typ
Max
Units
-
0.8
V
Conditions
PWM Dimming
VPWMD(Lo)
PWM input Low voltage
-
VPWMD(Hi)
PWM input High voltage
2.0
-
-
V
RPWMD
PWM pin pull-down resistance
90
100
130
KΩ
Over Voltage Protection
VOVP
Over-voltage threshold
1.15
1.20
1.25
V
OVP rising
TPD
Propagation delay time
-
150
-
ns
OVP=0-2V step
90
100
110
KHz
RT=910KΩ
270
300
330
KHz
RT=300KΩ
-
92
-
%
-
2.5
-
MHz
Oscillator
Fosc
Switching frequency
DMAX
Maximum duty cycle
Error Amplifier
(Note1)
GB
Gain bandwidth product
AV
Open loop gain
73
-
-
dB
75pF capacitance at
COMP pin
Output open
VO
Output voltage range
0.3
-
4.95
V
VCC=5.0V
gm
Transconductance
-
630
-
uA/V
Gate Driver
IG-SOURCE
Gate short-circuit current
60
-
-
mA
VGATE=0V, VDD=10V
IG-SINK
Gate sinking current
310
-
-
mA
VGATE=10V, VDD=10V
TG-RISE
Gate driver output rise time
-
35
50
ns
CL=1000pF, VDD=10V
TG-FALL
Gate driver output fall time
-
20
35
ns
CL=1000pF, VDD=10V
IF-SOURCE
Fault pin short-circuit current
45
-
-
mA
VFAULT=0V, VDD=10V
IF-SINK
Fault sinking current
60
-
-
mA
VFAULT=10V, VDD=10V
TF-RISE
Fault driver output rise time
-
165
-
ns
CL=1000pF, VDD=10V
TF-FALL
Fault driver output fall time
-
145
-
ns
CL=1000pF, VDD=10V
-
1.5
-
V
RT=910KΩ, RSLOPE=30KΩ
Slope Compensation
VSC (PEAK)
SC pin peak voltage
ISLOPE
Current source out of SC pin
GSLOPE
Internal current mirror ratio
0
-
100
uA
1.8
2
2.2
-
-
-
200
ns
1.7
2
2.1
-
RCS=1KΩ, RSLOPE=30KΩ
Output Short-Circuit
TOFF(S.C)
Propagation time for short-circuit detection
GIREF
Amplifier gain at IREF pin
IREF=400mV, FDBK=0-1V,
Fault goes from high to
low
IREF=400mV
Current Sense
TBLANK
Leading edge blanking
-
100
-
ns
TDELAY
Delay to output of PWM comparator
-
150
-
ns
COMP=CLIM=VCC,
VCS=0-600mV Step
Thermal Protection
TSD
Thermal shutdown temperature
-
140
-
℃
THYS
Thermal shutdown hysteresis
-
40
-
℃
Note1: Guaranteed by design
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4
Rev. 2.0 @ 2011/10
SM8205
TYPICAL OPERATION CHARACTERISTIC
Test Conditions:VIN=12V, CVCC=10uF, CVDD=1.0uF, RT=910K, TA=25℃,Unless otherwise noted.
PWMD = 0V
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Rev. 2.0 @ 2011/10
SM8205
TYPICAL OPERATION CHARACTERISTIC
Test Conditions:VIN=12V, CVCC=10uF, CVDD=1.0uF, RT=910K, TA=25℃,Unless otherwise noted.
FPWM=1KHz
10% to 90%
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90% to 10%
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Rev. 2.0 @ 2011/10
SM8205
BLOCK DIAGRAM
VDD
10V
LDO
VIN
5V
LDO
VCC
UVLO
To internal
Circuit
6.5V/7V
POR
CLIM
Current-Limit
Comparator
DIS
GATE
Blanking
CS
PWM
Comparator
100ns
R
Q
FAULT
1:2
Ramp
S
SC
RT
OSC
1.2V
10uA
SS
DIS
Q
R
Q
S
POR
OVP
DIS
E.A
FDBK
/7
IREF
COMP
100K
DIS
2
PWMD
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7
GND
Rev. 2.0 @ 2011/10
SM8205
BASIC OPERATION
Overview
Gate Driver Voltage (VDD)
The SM8205 is a current-mode, high-brightness LED
driver designed to control a single-string LED current
regulator with two external N-channel MOSFETs. It
integrates all the building blocks necessary to implement
a fixed-frequency, peak-current-mode control with
programmable slope compensation to control the duty
cycle of the PWM controller. The SM8205 allows
implementation of different converter topologies such as
SEPIC, Boost, Buck-Boost, Buck regulator. Basic
operating discussion that follows it will be helpful to refer
to the block diagram of the IC.
The SM8205's 10V LDO regulator powers up the
switching MOSFET driver. Use at least a 1uF low-ESR
ceramic capacitor from VDD to GND for best
performance. Careful choice of a lower Qg FET will allow
higher switching frequency, leading to smaller
magnetics. The VDD pin has it own undervoltage
disable (UVLO) set to 6.5V (typical value) to protect the
external MOSFET from excessive power dissipation
caused by not being fully enhanced.
Control and Reference Voltage (VCC)
The SM8205 has a 2% accurate, 5V reference, VCC. It
provides power to most of the internal circuit blocks
except for the gate drivers. It also can be used as the
reference for the LED output current as well as to set the
switch current limit through a resistor divider. Connect a
at least 4.7uF ceramic capacitor from VCC to GND.
In normal operation with the PWMD pin low level, the
GATE and FAULT pins are driven to GND, the COMP
pin is high impedance to store the previous switching
state on the external compensation capacitor, and the
FDBK pin bias current is reduced to leakage levels.
When the PWM pin transitions high level, the GATE pin
transition high after a short-delay. At the same time, the
internal oscillator generates a pulse to set the SR latch,
turning on the external power MOSFET switch(GATE
goes high), A voltage input proportional to the switch
current, sensed by an external current sense resistor
connected from CS and GND. This voltage is added to a
stabilizing slope compensation ramp and the resulting is
fed into the positive terminal of the PWM comparator.
The current in the external inductor increases steadily
during the time the switch is on. When this non-inversion
input voltage exceeds inversion input voltage of the error
amplifier E.A, the SR latch is reset and the external
power switch is turned off. During the switch off phase,
the inductor current decreases. At the completion of
each oscillator cycle, internal signals such as slope
compensation return to their starting point and a new
cycle begins with the set pulse from the oscillator.
Oscillator and Switching Frequency (RT)
The internal oscillator of the SM8205 is programmable
from 100KHz to 1MHz using a single resistor at RT, Do
not leave this pin open. Use the following formula to
calculate the RT value (1% resistors) :
1
RT ≈
FOSC (KHz) * 11 * 10
-9
Table 1. Operating Frequency Selection
FOSC (KHz)
RT (KΩ)
100
910
200
455
Minimum Input Voltage at Vin Pin
300
303
The SM8205 contains two internal high-voltage startup
regulator that allows the VIN pin to be connected directly
to line voltage as high as 46V. The 5V low dropout linear
regulator VCC, is used to power internal PWM controller,
control logic, error amplifier and as the reference for the
LED output current as well as to set switch current limit.
In application, connect a bypass capacitor from this pin
to GND, The recommended capacitance range is from
4.7uF to 10uF. Another 10V LDO regulator VDD, is for
external power MOSFETs driver, on the condition that
VIN≥12V, the regulator generates a 10V supply. If
7V≤VIN≤11V, the VDD is equal to VIN minus drop voltage
across bypass switch. When the voltage on the VDD pin
reaches the rising threshold of 7V, the GATE driver is
enabled. The GATE driver will remain enables until VDD
falls below 6.5V. Connect a bypass capacitor from this
pin to GND, The recommended capacitance range is
from 1.0uF to 10uF.
500
182
600
152
1000
91
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Note: Higher frequency operation yields smaller
component size but increases switching losses and gate
driving current, and may not allow sufficiently high or low
duty cycle operation. Lower frequency operation gives
better performance and efficiency but has larger external
component size.
Soft-start (SS)
The soft-start feature allows the LED output current to
gradually reach the LED current’s rate, thereby reducing
start-up stresses and input surge current. At power up,
after the VCC and input under-voltage lockout thresholds
are satisfied, an internal 10uA current source charges an
external capacitor connected to the SS pin. The
capacitor voltage will ramp up slowly and will limit the
COMP pin voltage and the switch current.
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Rev. 2.0 @ 2011/10
SM8205
Over-Voltage Protection (OVP)
Gate driver (GATE)
Over voltage protection is achieved by connecting the
output voltage to the OVP pin through a resistor divider.
The voltage at the OVP pin is constantly compared to
the internal 1.2V. When the output voltage at LED load
terminal is exceeded 1.2V, the IC is turned off,
immediately, at the same time the GATE and FAULT
pins goes low. Power on again to resume this situation.
The output voltage can be set by selecting the values of
R1 and R2 (see figure 1) according to the following
equation:
External MOSFETs are driven by the SM8205's internal
low impedance gate driver. These driver are biased from
the VDD and have a source current of 150mA and a sink
current of 300mA, to switch a ground-referenced Nchannel MOSFET in high-power applications. The
average current demanded from the supply to drive the
external MOSFET depends on the total gate charge (Qg)
and the operating frequency of the converter, FSW. Use
the following equation to calculate the driver supply
current IGATE required for the switching MOSFET:
R1+R2
VOUT = 1.2 •
IGATE = Qg x FSW
R2
SM8205
Dimming MOSFET Driver (FAULT)
The SM8205 requires an external N-channel MOSFET
for PWM dimming. Connect the gate of the MOSFET to
the output of the dimming driver, FAULT, for normal
operation. The dimming driver is capable of sourcing or
sinking up to 50mA of current.
VOUT
1.2V
R1
OVP
LED Current-Sense Input (FDBK)
R2
The current through the LED string is set via the value
chosen for the current sense resistor, RSN. This value
can be calculated using equation of below:
Figure 1. Over-voltage protection resistor connection
VIREF
ILED =
RSN
PWM Dimming (PWMD)
PWM dimming can be achieved by driving the PWMD
pin with a TTL compatible source. The PWM signal is
connected internally to the three different node – the
transconductance amplifier, the FAULT output, and the
GATE output.
COUT
SM8205
When the PWMD signal is high, the GATE and FAULT
pins are enabled, and the output of the EA amplifier is
connected to the external compensation network. Thus,
the internal amplifier controls the LED current. When the
PWMD signal goes low, the output of the EA amplifier is
disconnected from the compensation network. So, the
integrating capacitor maintains the voltage across it. The
GATE is disabled, the converter stops switching and the
FAULT pin goes low, turning off the disconnect switch.
By turning off the disconnect switch action, the output
capacitor is prevented from being discharged, and thus
the PWM dimming response of the boost converter
improvs dramatically.
FAULT
FDBK
RSN
ILED
Figure 2. LED Forward Current Controls Path
Another important parameter to be aware of in the boost
controller design, is the ripple current. The amount of
ripple current through the LED string is equal to the
output ripple voltage divided by LED AC resistance (RLED
is provided by the LED manufacturer) plus the current
sense and RON of the MOSFET resistor. The amount of
allowable ripple current through the LED string is
dependent upon the application and design’s discretion.
The equation is shown as below:
When the voltage at PWMD is greater than 2.0V, the
PWM dimming MOSFET turns on and when the voltage
on PWMD is below 0.8V, the PWM dimming MOSFET
turns off.
LED Current Reference (IREF)
The LED current is propotional to the voltage at IREF.
Applying an external DC voltage at IREF or using a
potentionmeter from IREF to GND allow analog dimming
of the LED current.
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ΔILED =
9
VOUT(RIPPLE)
RLED + RON + RSN
Rev. 2.0 @ 2011/10
SM8205
Slope Compensation (SC)
Current Limit (CLIM)
The SM8205 uses an internal ramp voltage generator
(typically at 1.5VPEAK) for slope compensation, by an
external resistor connects SC pin to GND to generate a
respective ramp current source for slope compensation
use. In a fixed operating frequency, slope compensation
is necessary, Particularly, the operating duty cycle
greater than 0.5. choosing a slope compensation which
is one-half of the down slope of the inductor current to
ensure the stability operation.
The SM8205 features a current limit protection feature to
prevent any current runaway conditions. Current limit
has to be set by a resistor divider from the VCC (5V)
reference available on the IC. Assuming a maximum
operating inductor current IPK (including the ripple
current), the voltage at the CLIM pin can set as:
VCLIM ≥ 1.2 • IPK • RCS +
Blanking
CS
(
5 • RSC
RSLOPE
)
• DMAX
100ns
Note that this equation assumes a current limit at 120%
of the maximum input current. Also, if VCLIM is greater
than 450mV, the saturation of the internal E.A amplifier
will determine the limit on the input current rather than
the CLIM pin. In such a case, the sense resistor RCS
should be reduced till VCLIM reduces below 450mV.
1:2
Ramp
1.5V/T
SC
Internal Transconductance Error Amplifier
The SM8205 has a built-in transconductance amplifier
used to amplify the error signal inside the feedback loop.
The amplified current-sense signal is connected to the
negative input of the gm amplifier with the current
reference connected to IREF. The output of the op-amp
is controlled by the input at PWMD. When the signal at
PWMD is high, the output of the op-amp connects to
COMP; when the signal at PWMD is low, the output of
the op-amp disconnects from COMP to keep the charge
on the compensation capacitor. When the voltage at
PWMD goes high, the voltage on the compensation
capacitor forces the converter into a steady state. COMP
is connected to the negative input of the PWM
comparator with CMOS input through a buffer, forward
diode and 7:1 resistor divider, which draw a small
current from the compensation capacitor at COMP and
thus prevent discharge of the compensation capacitor
when the PWMD input is low.
RSLOPE
Figure 3. The Functional Block of the Ramp Current
Slope compensation can be programmed by two
resistors RSLOPE and RSC. Assuming a down slope of
DS (A/uA) for the inductor current, the slope
compensation resistors can be computed as:
10 • RSC
RSLOPE =
6
DS • 10 • Ts • RCS
■ A typical value for RSC is 620Ω.
Current Sense (CS)
The current sense input of the SM8205 built-in a 100ns
(typical, see figure 3.) blanking time to prevent spurious
turn off due to the initial current spike when the external
power MOSFET turns on. SM8205 includes two highspeed comparator – one is used during normal
operation, namely is PWM comparator, another one is
used to limit the maximum input current during input
under-voltage or overload conditions, which namely is
current-limit comparator.
FAULT Protection
The SM8205 includes a output over-voltage and LED
short-circuit protections. Both protection features are
latched, which means that the power to the IC must be
recycled to reset the IC. The IC also built-in a FAULT pin
which goes low during any fault conditions. At start-up, a
monoshot circuit (trigger by POR the circuit), reset an
internal SR filp-flop which causes FAULT to go high,
and remains high during normal operation. This also
allows the GATE drive to function normally. This pin can
be used to drive an external switch Q2 (see typical
application on page 1), which will disconnect the load
during a fault condition. This disconnect switch is very
important in a boost converter, as turning off the
switching MSOFET (Q1) during an output short-circuit
condition will not remove the fault (Q1 is not in the path
of the fault current), the disconnect switch will help to
disconnect the shorted load from the input.
The SM8205 integrates an internal resistor divider
network, which steps down the voltage at the COMP pin
by a factor of 7 (see IC’s block diagram). This steps
down voltage is fed to one of the PWM comparator as
the current reference. The reference to the other
comparators (current-limit comparator), which acts to
limit the maximum inductor current, is given externally.
It is recommended that the sense resistor RCS be
chosen so as to provide about 250mV current sense
signal.
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Rev. 2.0 @ 2011/10
SM8205
LED Short-Circuit Protection
Thermal Shutdown
Internal thermal shutdown circuitry is provided to protect
the SM8205 in the event that the maximum junction
temperature is exceeded. When activated, typically at
140℃, the controller is forced to disable the output
GATE and FAULT drivers in low-state. After the
temperature is reduced (typical hysteresis is 25℃) the
gate driver will be re-enabled.
The LED short-circuit condition is indicated by FAULT.
At start-up, a monoshot circuit (triggered by the POR
circuit), reset an internal SR flip-flop, which causes
FAULT to go high, and remains high during normal
operation. This also allows the GATE driver to function
normally. The steady state current is reflected in the
reference voltage connected to the transconductance
amplifier. The instantaneous output current is sensed
from FDBK terminal of the op-amp. The short-circuit
threshold current is internally set to 200% of the steady
state current. During short-circuit condition, when the
current exceeds the internally set threshold, the SR flipflop is set and FAULT goes low. Meanwhile, the GATE
driver of the power MOSFET is inhibited, providing a
latching protection. The converter can be reset by
cycling the input voltage for operating again.
Current Sense Filter
Parasitic circuit capacitance, inductance and gate driver
current create a spike in the current sense voltage at the
point where Q1 turns on. In order to prevent this spike
from terminal the on-time prematurely, every circuit
should have a low-pass filter that consists of RF and CF,
shown in figure 4. The time constant of this filter should
be long enough to reduce the parasitic spike without
significantly affecting the shape of the actual current
sense voltage. The recommended range for RF is
between 10Ω and 500Ω, and CF is between 100pF and
2.2nF.
VIN
CIN
D1
SM8205
Q1
GATE
RF
CS
CF
RCS
Figure 4. Adding a low-pass filter to prevent
premature triggering
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11
Rev. 2.0 @ 2011/10
SM8205
Application Circuit 1 – For a Boost DC to DC Converter
L1
D1
VIN
VOUT
CIN
CO
CCC
1
VCC
2
RT
3
R1
4
R2
R3
VDD
RT
GATE
CS
PWMD
6
FAULT
COMP
7
8
R4
SS
CLIM
5
CCOMP RCOMP
VIN
SC
IREF
OVP
GND
FDBK
RP1
RFD1
16
15
CDD
RP2
Q1
14
12
RSC
13
11
RFD2
RCS
RSLOPE
10
9
SM8205
Application Circuit 2 – For a SPEIC LED Driver
C1
L1
D1
VOUT
VIN
CO
CIN
CCC
1
2
RT
R1
R2
3
4
5
CCOMP RCOMP
R3
R4
6
7
8
VCC
VIN
SS
VDD
RT
GATE
CLIM
CS
PWMD
OVP
COMP
SC
IREF
FAULT
GND
FDBK
16
15
RP2
Q1
RSC
RCS
10
11
RSLOPE
13
9
RSN
SM8205
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L2
CDD
14
12
RP1
12
Rev. 2.0 @ 2011/10
SM8205
PACKAGE DIMENSIONS
SM8205 16 PIN SOP
16
9
C
E
θ°
L
H
1
8
D
A
B
A1
e
X
DIM
Y
A
0.0532
0.0688
1.35
1.75
0.0040
0.0096
0.10
0.25
B
0.013
0.020
0.33
0.51
C
0.0075
0.0096
0.19
0.25
D
0.3859
0.3937
9.80
10.00
E
0.1497
0.1574
3.80
4.00
e
C2
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MILLIMETERS
MIN
MAX
A1
C1
RECOMMENDED LAND PATTERN
INCHES
MIN
MAX
0.050 BSC.
1.27 BSC.
H
0.2284
0.2440
5.80
6.20
L
0.016
0.050
0.40
1.27
θ°
0°
8°
0°
8°
X
0.0236
0.60
Y
0.0590
1.50
C1
0.2125
5.4
C2
0.0499
1.27
13
Rev. 2.0 @ 2011/10