datasheet for ZD810 by Zywyn

datasheet for ZD810 by Zywyn
ZD810 Univeral High Brightness LED Driver
Zywyn
Features
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Universal High Brightness LED Driver
General Description
Low cost and high-efficiency LED driver
Form and fit compatible with market solutions
Open loop peak current controller
Internal 8.0 to 450V linear regulator
Constant frequency / constant off-time operation
0- 250 mV linear dimming
0 - 100% PWM dimming
Requires few external components
8-Lead NSOIC Green Package
Applications
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ZD810
AC/DC and DC/DC LED driver applications
Lighting, recessed lighting, street lighting
Signage and decorative lighting
RGB backlighting, flat panel backlighting
LED control powered by the Mains
General purpose constant current source
Chargers
The ZD810 is a dimmable current-mode constant current
LED driver IC. It drives an external MOSFET to accurately
regulate the current in the LED string. The MOSFET can be
sized for all types of LEDs including Power and HB LEDs
beyond 1W. Its robust 450V rating makes it universally applicable to systems powered directly from Mains sources
or from popular PFC sources. Its low voltage rating of 8V
makes is suitable as well for low/medium voltage sources.
The internal linear regulator generates 7.5V at the Vdd pin,
which is also made available for external use, thus saving
the cost of an external regulator.
Current dimming can be achieved through the 0 - 250mV
linear dimming on Pin LD, or else by PWM methods on the
PWMD pin with a duty cycle ratio of 0 - 100% and a frequency
of up to a few kHz.
The ZD810 is ideally suited for buck topology based LED
drivers. Since it operates in open loop current mode control,
the controller achieves good output current regulation without
the need for any loop compensation.
The ZD810 is an ideal and affordable driver for low cost
LED string control solutions, requiring only three external
components (apart from the power MOSFET).
Ordering Information
Part Number
Temperature Range
ZD810LEN
Pin Configuration
Package Type
–40°C to +85°C
ZD810NEVB
8-Pin nSOIC
n/a
For 8-Pin nSOIC
Please contact the factory for pricing and availabiliy on Tape-on-Reel
option.
8 ROSC
VIN 1
CS 2
Zywyn
7 LD
GND 3
ZD810
6 VDD
GATE 4
Typical Application
VIN
5 PWMD
CIN
COUT
D1
8-Pin nSOIC
VIN
VDD
LD
CDD
W
ZD810
GATE
L
PWMD
PWMD
L1
M1
CS
ROSC
GND
ROSC
RCS
Figure 1. ZD810 Typical Application
Zywyn
Specifications subject to change without notice
1 • Email [email protected] • www.zywyn.com
Zywyn Corporation • Tel (408) 733-3225 • Fax (408) 733-3206
June 2010
rev. 1.1
Zywyn Corporation
ZD810
Absolute Maximum Ratings
Storage Considerations
These are stress ratings only and functional operation of the
device at these ratings or any other above those indicated
in the operation sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended
periods of time may affect reliability.
Storage in a low humidity environment is preferred. Large
high density plastic packages are moisture sensitive and
should be stored in Dry Vapor Barrier Bags. Prior to usage,
the parts should remain bagged and stored below 40°C and
60%RH. Zywyn ships products in Dry Vapor Barrier Bags with
a humidity indicator card and desiccant pack. The humidity
indicator should be below 30%RH. The MSL of this product
is 1 and has an unlimited amount of hours it can be stored
outside of the bag.
The information furnished by Zywyn has been carefully
reviewed for accuracy and reliability. Its application or use,
however, is solely the responsibility of the user. No responsibility of the use of this information become part of the terms and
conditions of any subsequent sales agreement with Zywyn.
Specifications are subject to change without the responsibility
for any infringement of patents or other rights of third parties
which may result from its use. No license or proprietary rights
are granted by implication or otherwise under any patent or
patent rights of Zywyn Corporation.
VIN Voltage ...........................................................480VDC
VDD Voltage ..............................................................12VDC
CS, LD, PWMD, GATE, ROSC Voltage .......... VIN+0.7VDC
Extended Commercial
Operating Temperature .......................... –40°C to +85°C
Maximum Junction Temperature ............................. +150°C
Storage Temperature ................................ –65°C to +150°C
Lead Temperature (Soldering, 10sec.) ...................... 300°C
Power Dissipation Per Package (TA = 25°C)
8-pin nSOIC ............................................................ 630mW
Package Thermal Resistance
ΘJA (8-PIN) ............................................................ 128°C/W
Specifications subject to change without notice
2
June 2010
rev. 1.1
Zywyn Corporation
ZD810
Electrical Characteristics
TA = +25°C, VIN = 12V unless otherwise noted.
Parameter
Condition
Min
Typ
Max
Units
INPUT
VIN, Input DC supply voltage
range (1) (3)
DC input voltage
8
-
450
V
IINSD, Shut-down mode supply
current (3)
Pin PWMD = GND
-
0.5
1.0
mA
7.25
7.5
7.75
V
ΔVDD, LINE, Line regulation of VDD VIN = 8V - 450V, IDD = 0 (2), 500pF @ Gate,
ROSC = 226kΩ, PWMD=VDD
0
-
1
V
ΔVDD, Load, Load regulation of
VDD
IDD = 0 ~ 1mA, 500pF @ Gate, ROSC = 226kΩ,
PWMD=VDD
0
-
100
mV
UVLO, VDD undervoltage lockout
threshold (3)
VDD Rising
6.45
6.7
6.95
V
ΔUVLO, VDD undervoltage lockout hysteresis
VDD Falling
-
500
-
mV
5
-
-
mA
INTERNAL REGULATOR
VDD, Internally regulated voltage
VIN = 8V, IDD = 0 (2), 500pF @ Gate, ROSC =
226kΩ, PWMD=VDD
IIN, MAX, Current that the regulator VIN = 8V
can supply before IC goes into
UVLO (4)
PWM DIMMING
VEN(LOW) , Pin PWMD input low
voltage (3)
VIN = 8 - 450V
-
-
0.8
V
VEN(HIGH) , Pin PWMD input high
voltage (3)
VIN = 8 - 450V
2
-
-
V
REN , Pin PWMD pull-down resistance at PWMD
VPWMD = 5V
50
100
150
kΩ
CURRENT SENSE COMPARATOR
VCS,TH , Current sense pull-in
threshold voltage
-40°C < TA < +85°C
225
250
275
mV
TA < +125°C
213
250
287
mV
-12
-
12
mV
VOFFSET , Offset voltage for LD
comparator (3)
tBLANK , current sense blanking
interval (3)
VLD = VDD, VCS=VCS,TH +50mV after tBLANK
150
215
280
ns
tDELAY , Delay to output
VLD = VDD, VCS=VCS,TH +50mV after tBLANK
-
80
150
ns
ROSC = 1MΩ
20
25
35
kHz
ROSC = 226KΩ
80
100
120
kHz
ISOURCE , Gate sourcing current
VGATE=0V, VDD=7.5V
165
-
-
mA
ISINK , Gate sinking current
VGATE=VDD, VDD=7.5V
165
-
-
mA
OSCILLATOR
fOSC , oscillator frequency
GATE DRIVER
tRISE , Gate to output rise time
CGATE=500pF, VDD=7.5V
-
30
50
ns
tFALL , Gate to output fall time
CGATE=500pF, VDD=7.5V
-
30
50
ns
Notes:
(1) Also limited by package power dissipation limit, whichever is lower.
(2) VDD load current external to the ZD810.
(3) Denotes the specifications which apply over the full operating ambient temperature range of -40°C < T A < +125°C.
(4) Guaranteed by design.
Specifications subject to change without notice
3
June 2010
rev. 1.1
Zywyn Corporation
ZD810
Block Diagram
VIN
Linear
Regulator
Power On Reset
ROSC
OSCILLATOR
7.5V
VDD
S
LD
Q
GATE
CS
R
250mV
GND
PWMD
Fig.2. ZD810 Block Diagram
Specifications subject to change without notice
4
June 2010
rev. 1.1
Zywyn Corporation
ZD810
Pin Description
8-pin
SOIC
Name
Description
1
VIN
Input. Main power for the LED Driver system. It is the input for the High Voltage (8 ~ 450V) Linear
Regulator
2
CS
Current Sense. Used to sense current peaks in the inductor, through a sense resistor to GND.
Nominally, the current sensors will trip when the voltage at CS is 250mV, or else the Linear dimming value, if it is lower.
3
GND
Return point for all circuitry. This must be anchored to the lowest available potential in the system.
4
Gate
Gate Drive to the external Power MOSFET
5
PWMD
Pulse Width Modulation Dimming. PWM diming can be performed through this pin. Should be
driven with square waves in the low kHz. A logic low input here will turn off the MOSFET driver. If
this pin is tied to VDD, PWMD is not operative.
6
VDD
This internally-regulated DC voltage can provide up to 5mA for external circuitry.
7
LD
Linear Dimming. For input voltages less than 250mV, this can be used to linearly adjust the LED
brightness. If tied to Vdd, then Linear Dimming is not operative.
8
ROSC
A resistor from here to GND sets the oscillator frequency. From here to Gate sets Constant offtime.
Specifications subject to change without notice
5
June 2010
rev. 1.1
Zywyn Corporation
ZD810
Circuit Description
APPLICATION INFORMATION
INPUT VOLTAGE REGULATOR
The ZD810 is an optimized buck topology LED driver
using an open-loop peak current mode control. Accurate
LED current control can be achieved without the need for
high side current sensing or the design of any closed loop
controllers. The ZD810 can be dimmed using Linear and
PWM dimming of the LED current.
When a voltage is applied at the VIN pin of 8.0 ~ 450VDC,
the ZD810 maintains a constant 7.5V at the VDD pin. This
voltage is used to power the internal circuits of the IC and
any external circuits needed to control the IC.
The VDD pin must be bypassed by a low ESR capacitor to
provide a low impedance path for the high frequency current of the output GATE driver.
The ROSC resistor sets the frequency of operation (or the
off-time) of the ZD810. The internal oscillator produces pulses at regular intervals that set the SR flip-flop in the ZD810
which causes the Gate driver to turn on. These pulses also
start the Blanking timer which controls the reset input of the
SR flip flop to prevent false turn-offs due to turn-on spikes.
When the MOSFET turns on, the current through the inductor starts ramping up and the current flows through the
external sense resistor RCS, producing a ramp voltage at
the CS pin. The two comparators are constantly comparing
the CS pin voltage to both the voltage at the LD pin and the
internal 250mV. Once the blanking timer is complete, the
output of these comparators is allowed to reset the flip flop.
When the output of either one of the two comparators goes
high, the flip flop is reset and the Gate output goes low. The
Gate goes low until the SR flip flop is set by the oscillator.
Assuming a 30% ripple in the inductor, the current sense
resistor RCS can be set using:
The ZD810 can be operated without using the VIN pin by
supplying a voltage of 7.5V~12V at the VDD pin. This will
turn off the internal linear regulator of the IC and the ZD810
will operate directly off the voltage supplied at the VDD pin.
The VIN pin of the ZD810 is rated up to 450V, but is also
limited by the power dissipation in the IC.
Example: 8-pin nSOIC has a junction to ambient thermal
resistance R JA = 128°C/W.
The ZD810 draws about IIN = 2.0mA from the VIN pin, and
has a maximum allowable temperature rise of the junction
temperature limited to about T = 100°C, the maximum voltage at the VIN pin would be:
VIN ( MAX ) =
RCS =
0.25V (or VLD )
1.15 ⋅ ILED( A)
∆T 1
100 o C
1
⋅
=
⋅
= 390V
o
RθJA I IN 128 C / W 2mA
To operate the ZD810 at higher input voltages, a 100V
Zener diode can be added in series with the VIN pin to divert
some of the power loss and allow for 450V operation.
Constant frequency peak current mode control goes into
sub-harmonic oscillations when the duty cycle is greater
than 0.5. An artificial slope is can be added to the current
sense waveform but can affect the accuracy of the LED current.
The input current drawn from the VIN pin is a sum of the
1.0mA current drawn by the internal circuit and the current
drawn by the GATE driver (which in turn depends on the
switching frequency and the GATE charge of the external
FET).
A constant off-time peak current control can easily operate
at duty cycles greater then 0.5 and also gives input voltage
rejection making the LED current almost insensitive to input
voltage variations. This can lead to variable frequency operation depending greatly on the input and output voltage
variation. ZD810 allows for both constant frequency and
constant off-time modes of operation by changing one connection (see oscillator section).
IIN ≈ 1.0mA + Qg • fS
In the above equation, fS is the switching frequency and
Qg is the GATE charge of the external FET (which can be
obtained from the datasheet of the FET).
Specifications subject to change without notice
6
June 2010
rev. 1.1
Zywyn Corporation
ZD810
Circuit Description
CURRENT SENSE
LINEAR DIMMING
The current sense input (CS pin) of the ZD810 goes to the
noninverting inputs of two comparators. One comparator
compares the CS pin with the LD pin and the other comparator compares the CS with the internal 250mV reference
voltage. The outputs of these comparators input to the and
OR GATE that is connected tot he reset pin of the SR flipflop. The comparator with the lowest voltage at the inverting
terminal determines when the GATE output is turned off.
The Linear Dimming pin (LD) is used to control the LED
current. An external 0-250mV voltage can be connected to
the LD pin to adjust the LED current. The LD pin should be
connected to VDD if linear dimming is not desired.
An external voltage divider from the VDD pin can be connected to the LD pin to obtain a voltage (less than 250mV)
corresponding to the desired voltage across RCS.
The outputs of the comparators include a 150 ~ 280ns
blanking time which prevents false turn-offs of the external
MOSFET due to the turn-on spike normally present in peak
current mode control. An RC filter may be added between
the external sense resistor (RCS) and the CS pin if the blanking time is not adequate enough to filter out the spikes. A
proper layout of the PCB, minimizing external inductances,
will prevent false triggering of these comparators.
Note: Although the LD pin can be pulled to GND, the output current
will not go to zero. This is due to the presence of a minimum ontime (which is equal to the sum of the blanking time and the delay
to output time) which is about 450ns.
This will cause the FET to be on for a minimum of 450ns and thus
the LED current when LD = GND will not be zero. This current is
also dependent on the input voltage, inductance value, forward
voltage of the LEDs and circuit parasitics. To get zero LED current,
the PWMD pin has to be used.
PWM Dimming
OSCILLATOR
PWM Dimming can be achieved by driving the PWMD pin
with a low frequency square wave signal. A logic high and
a logic low will enable and disable the GATE driver respectively. The PWMD does not affect other parts of the IC and
the rate of rise and fall of the LED current is determined
solely by the rise and fall times of the inductor current.
To disable PWM dimming and enable the ZD810 permanently, connect the PWMD pin to VDD.
The ZD810 can operate in constant frequency mode or
constant off-time mode by terminating the external resistor ROSC in different locations. If the resistor is connected
between ROSC and GND, the ZD810 operates in a constant
frequency mode and the equation below determines the
time-period. If the resistor is connected between ROSC and
GATE, the ZD810 operates in a constant off-time mode and
the equation below determines the offtime.
tOSC ( µs ) =
ROSC (kΩ) + 22
25
GATE OUTPUT
The GATE output of the ZD810 drives the GATE of the external MOSFET. It is recommended that the GATE charge
of the external FET be less than 25nC for switching frequencies ≤100kHz and less than 15nC for switching frequencies > 100KHz
Specifications subject to change without notice
7
June 2010
rev. 1.1
Zywyn Corporation
ZD810
Green Package SMD IR Reflow Profile Information
IR Reflow Profile Conditions
Profile Feature
Average Ramp-Up Rate
(TSmax to TP)
Pre-heat
- Temperature Min (TSmin)
- Temperature Max (TSmax)
- Time (TSmin to tSmax)
Time maintained above:
- Temperature (TL)
- Time (tL)
Peak/Classification
Temperature (TP)
JESD Sn-Pb Eutectic Assembly
o
3 C/seconds max.
o
3 C/seconds max.
o
150 C
o
200 C
60~180 seconds
o
217 C
60~150 seconds
100 C
o
150 C
60~120 seconds
183 C
60~150 seconds
o
JESD Pb-free Assembly
o
o
o
o
o
235 C+5/-0 C
255 C+5/-0 C
10~30 seconds
20~40 seconds
o
Time within 5 C of actual Peak
Temperature (tP)
Ramp-Down Rate
o
o
6 C/second max.
6 C/second max.
6 minutes max.
8 minutes max.
o
Time 25 C to Peak
Temperature
Zywyn Green Packages are Pb-free and RoHS compliance.
Specifications subject to change without notice
8
June 2010
rev. 1.1
Zywyn Corporation
ZD810
Package Information
8-Pin nSOIC
ZYWYN CORPORATION
Specifications subject to change without notice
9
June 2010
rev. 1.1
Zywyn Corporation
ZD810
Part Marking Information
TOPSIDE MARK INSTRUCTIONS:
Line 1
Notch
ZD810LEN YYWW
(Lot#).T
Line 2
Line 3
Pin 1 Indicator and
Mold Dimple
Line 1:
Line 2:
Line 3:
Note:
Zywyn (logo)
Zywyn Part Number "ZD810LEN", Space " ", Date Code (Prod Year & Week)
Lot #, dot and Country ".T"
Pin # 1 " " Indicator Required if no mold dimple
BOTTOMSIDE MARK INSTRUCTIONS:
No backside marking
8-Pin nSOIC
Zywyn Corporation
Headquarters and Sales Office
1270 Oakmead Parkway, Suite 201 • Sunnyvale, CA 94085 • Tel: (408) 733-3225 • Fax: (408) 733-3206
Email: [email protected] • www.zywyn.com
Zywyn Corporation reserves the right to make changes to any products described herein. Zywyn does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
© 2010 Zywyn Corporation
Specifications subject to change without notice
10
June 2010
rev. 1.1
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