Microchip MIC3231 Bedienungsanleitung


Lesen Sie kostenlos die 📖 deutsche Bedienungsanleitung für Microchip MIC3231 (19 Seiten) in der Kategorie Nicht kategorisiert. Dieser Bedienungsanleitung war für 29 Personen hilfreich und wurde von 2 Benutzern mit durchschnittlich 4.5 Sternen bewertet

Seite 1/19
MIC3230/1/2
Constant Current Boost Controller for
Driving High Power LEDs
Bringing the Power to Light is a trademark of Micrel, Inc.
MicroLeadFrame and MLF are registered trademarks of Amkor Technology.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
March 2011
M9999-030311-D
General Description
The MIC3230/1/2 are constant current boost switching
controllers specifically designed to power one or more
strings of high power LEDs. The MIC3230/1/2 have an
input voltage range from 6V to 45V and are ideal for a
variety of solid state lighting applications.
The MIC3230/1/2 utilizes an external power device which
offers a cost conscious solution for high power LED
applications. The powerful drive circuitry can deliver up to
70W to the LED system. Power consumption has been
minimized through the implementation of a 250mV
feedback voltage reference providing an accuracy of ±3%.
The MIC323x family is dimmable via a pulse width
modulated (PWM) input signal and also features an enable
pin for low power shutdown.
Multiple MIC3230 ICs can be synchronized to a common
operating frequency. The clocks of these synchronized
devices can be used together in order to help reduce noise
and errors in a system.
An external resistor sets the adjustable switching
frequency of the MIC3230/1. The switching frequency can
be between 100kHz and1MHz. Setting the switching
frequency provides the mechanism by which a design can
be optimized for efficiency (performance) and size of the
external components (cost). The MIC323x family of LED
drivers also offer the following protection features: Over
voltage protection (OVP), thermal shutdown and under-
voltage lock-out (UVLO).
The MIC3231 offers a dither feature to assist in the
reduction of EMI. This is particularly useful in sensitive EMI
applications, and provides for a reduction or emissions by
approximately 10dB.
The MIC3232 is a 400kHz fixed frequency device offered
in a small 10-pin MSOP package. The MIC3230/1 are
offered in both the EPAD 16-pin TSSOP package and the
12-pin 3mm × 3mm MLF® package.
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Bringing the Power to Light™
Features
6V to 45V input supply range
Capable of driving up to 70W
Ultra low EMI via dithering on the MIC3231
Programmable LED drive current
Feedback voltage = 250mV ±3%
Programmable switching frequency (MIC3230/1) or
400kHz fixed frequency operation (MIC3232)
PWM Dimming and separate enable shutdown
Frequency synchronization with other MIC3230s
Protection features:
Over Voltage Protection (OVP)
Over temperature protection
Under-voltage Lock-out (UVLO)
Packages:
IADJ IS65
1VIN
EN
PWMD
COMP
10 VDD
DRV
PGND
OVP
9
8
7
2
3
4
IADJ IS
VIN
EN
PWMD
COMP
1 VDD
DRV
PGND
OVP
2
3
4
5
FS EPAD SYNC/NC6
8
12
11
10
9
7
1N/C
VIN
EN
PWMD
COMP
IADJ
FS
AGND
16 N/C
VDD
DRV
PGND
OVP
IS
SYNC/NC
N/C
15
14
13
12
11
10
9
2
3
4
5
6
7
8EPAD
MIC3232
10-pin MSOP
MIC3230/1
12-pin MLF®
MIC3230/1
16-pin TSSOP
–40°C to +125°C junction temperature range
Applications
Street lighting
Solid state lighting
General illumination
Architectural lighting
Constant current power supplies
Micrel, Inc. MIC3230/1/2
March 2011 2 M9999-030311-D
Typical Application
L
47µH D1
R8
100k
R9
4.33k
COUT
4.7µF
100V
R2
100k
RADJ
1/4W
RFS
16.5k CCOMP
10nF
CIN
4.7µF/50v
RSLC
51
VFB = 0.25V RCS
1/2W
Analog ground Power ground
VOUTVIN
PWMD
ENABLE
Synch to other MIC3230
ILED Return
LED 1
LED XQ1
COMP
PWMD
VDD
AGND PGND
EPAD
IS
OVP
DRV
VIN
EN
IADJ
MIC3230/31
SYNC
FS
C3
10µF
10V
Figure 1. Typical Application of the MIC3230 LED Driver
Product Option Matrix
MIC3230 MIC3231 MIC3232
Input Voltage 6V to 45V 6V to 45V 6V to 45V
Synchronization Yes No No
Dither No Yes No
Frequency Range Adj from 100kHz to 1MHz Adj from 100kHz to 1MHz Fixed Freq. = 400kHz
Package 16-pin EPAD TSSOP
12-pin 3mm × 3mm MLF®
16-pin EPAD TSSOP
12-pin 3mm × 3mm MLF® 10-pin MSOP
Ordering Information
Part Number Temperature Range Package Lead Finish
MIC3230YTSE –40° to +125°C 16-pin EPAD TSSOP Pb-Free
MIC3230YML –40° to +125°C 12-pin 3mm x 3mm MLF® Pb-Free
MIC3231YTSE –40° to +125°C 16-pin EPAD TSSOP Pb-Free
MIC3231YML –40° to +125°C 12-pin 3mm x 3mm MLF® Pb-Free
MIC3232YMM –40° to +125°C 10-pin MSOP Pb-Free
Micrel, Inc. MIC3230/1/2
March 2011 3 M9999-030311-D
Pin Configuration
IADJ IS65
1VIN
EN
PWMD
COMP
10 VDD
DRV
PGN
D
OVP
9
8
7
2
3
4
IADJ IS
VIN
EN
PWMD
COMP
1 VDD
DRV
PGND
OVP
2
3
4
5
FS EPAD SYNC/NC6
8
12
11
10
9
7
1N/C
VIN
EN
PWMD
COMP
IADJ
FS
AGND
16 N/C
VDD
DRV
PGND
OVP
IS
SYNC/NC
N/C
15
14
13
12
11
10
9
2
3
4
5
6
7
8EPAD
10-Pin MSOP (MM)
MIC3232
12-Pin 3mmx3mmMLF® (ML)
MIC3230, MIC3231
See Product Option Matrix for selection
16-Pin TSSOP (TSE)
MIC3230, MIC3231
See Product Option Matrix for selection
Pin Description
Pin Number
MLF®
Pin Number
TSSOP
Pin Number
MSOP
Pin Name Pin Function
-- 1 -- NC No Connect.
1 2 1 VIN Input Voltage (power) 6V to 45V.
2 3 2 EN Enable Control (Input). Logic High ( 1.5V) enables the
regulator. Logic Low (0.4V) shuts down the regulator.
Connect a 100k resistor from EN to VIN.
3 4 3 PWMD PWM Dimming Input. Logic Low will disable the brightness
control of the LED drivers.
4 5 4 COMP Compensation (output): for external compensation.
5 6 5 IADJ Feedback (input).
6 7 -- FS Frequency Select (input). Connected to a Resistor to
determine the operating frequency.
-- 8 -- AGND Analog Ground.
-- 9 -- NC No Connect.
7 10 -- SYNC Sync (output). Connect to another MIC3230 to synchronize
multiple converters.
8 11 6 IS Current Sense (input). Connected to external current sense
resistor which in turn is connected to the source of the external
FET as well as an external slope compensation resistor.
9 12 7 OVP OVP divider connection (output). Connect the top of the
divider string to the output. If the load is disconnected, the
output voltage will rise until OVP reaches 1.25V and then will
regulate around this point.
10 13 8 PGND Power Ground.
11 14 9 DRV Drive Output: connect to the gate of external FET (output).
12 15 10 VDD VDD Filter for internal power rail. Do not connect an external
load to this pin. Connect 10µF to GND.
-- 16 -- NC No Connect.
-- -- -- EPAD Connect to AGND.
Micrel, Inc. MIC3230/1/2
March 2011 4 M9999-030311-D
Absolute Maximum Ratings(1)
Supply Voltage (VIN).....................................................+48V
Enable Pin Voltage........................................... -0.3V to +6V
IADJ Voltage ..................................................................+6V
Lead Temperature (soldering, sec.) ........................... 260°C
Storage Temperature (Ts)..........................-65°C to +150°C
ESD Rating(3)
MIC3230 ....................................... 1500V HB, 100VMM
MIC3232 ........................................... 2kV HB, 100VMM
MIC3231 ....................................... 1500V HB, 150VMM
Operating Ratings(2)
Supply Voltage (VIN)......................................... +6V to +45V
Junction Temperature (TJ)........................–40°C to +125°C
Junction Thermal Resistance
MSOP (θJA) ...................................................130.5°C/W
EPAD TSSOP (θJA).........................................36.5°C/W
MLF® (θJA).......................................................60.7°C/W
Electrical Characteristics(4)
VIN = 12V; VEN = 3.6V; L = 47µH; C = 4.7µF; TJ = 25°C, Bold values indicate –40°C TJ
+125°C, unless noted.
Symbol Parameter Condition Min Typ Max Units
VIN Supply Voltage Range 6 45 V
UVLO Under Voltage Lockout 3.5 4.9 5.5 V
IVIN Quiescent Current VFB > 275mV (to ensure device is not
switching)
3.2 10 mA
ISD Shutdown Current VEN = 0V 30 µA
Room temperature (3%) 242.5 250 257.5 mV VIADJ
Feedback Voltage (at IADJ)
–40°C TJ +125°C (5%) 237.5 250 262.5 mV
IADJ Feedback Input Current VFB = 250mV 1.2 3 µA
Line Regulation V
IN = 12V to 24V 2 %
Load Regulation V
OUT to 2 × VOUT 2 %
DMAX
Maximum Duty Cycle MIC3230 & MIC3232
MIC3231
90
88
%
%
VEN
Enable Threshold Turn ON
Turn OFF
1.5 1.15
1.1
0.4
V
V
IEN Enable Pin Current VEN = 3.3V
REN = 100k
17 30 µA
VPWM
PWMD Threshold Turn ON
Turn OFF
1.5 0.75
0.7
0.4
V
V
fPWMD
PWMD Frequency Range Note 5 (L = 47µH; C = 4.7µF) 0 500 Hz
fSW Programmable Oscillator
Frequency
RFREQ = 82.5k
RFREQ = 21k
RFREQ = 8.25k
360
109
400
950
440
kHz
kHz
kHz
fSW Fixed Frequency Option (MIC3232YMM) 360 400 440 kHz
FDITHER Low EMI (MIC3231) Frequency dither shift from nominal ±12 %
V
SENS Current Limit Threshold Voltage R
SENSE = 390 0.315 0.45 0.585 V
ISENSE
ISENSE Peak Current Out R
SENSE = 390 250 µA
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
5. Guaranteed by design
Micrel, Inc. MIC3230/1/2
March 2011 5 M9999-030311-D
Electrical Characteristics (Continued)
Symbol Parameter Condition Min Typ Max Units
VOVP Over Voltage Protection 1.203 1.24 1.277 V
Driver Impedance Sink
Source
2.4
2
3.5
VDRH Driver Voltage High VIN = 12V 7 9 11 V
TJ Over-Temperature Threshold
Shutdown
150 °C
Thermal Shutdown Hysteresis 5 °C
Micrel, Inc. MIC3230/1/2
March 2011 6 M9999-030311-D
Typical Characteristics
Micrel, Inc. MIC3230/1/2
March 2011 7 M9999-030311-D
Micrel, Inc. MIC3230/1/2
March 2011 8 M9999-030311-D
Functional Description
A constant output current converter is the preferred
method for driving LEDs. Small variations in current have a
minimal effect on the light output, whereas small variations
in voltage have a significant impact on light output. The
MIC323x family of LED drivers are specifically designed to
operate as constant current LED Drivers and the typical
application schematic is shown in Figure 1.
The MIC323x family is designed to operate as a boost
controller, where the output voltage is greater than the
input voltage. This configuration allows for the design of
multiple LEDs in series to help maintain color and
brightness. The MIC323x family can also be configured as
a SEPIC controller, where the output voltage can be either
above or below the input voltage.
The MIC3230/1/2 have a very wide input voltage range,
between 6V and 45V, to help accommodate for a diverse
range of input voltage applications. In addition, the LED
current can be programmed to a wide range of values
through the use of an external resistor. This provides
design flexibility in adjusting the current for a particular
application need.
The MIC3230/1/2 features a low impedance gate driver
capable of switching large MOSFETs. This low impedance
helps provide higher operating efficiency.
The MIC323x family can control the brightness of the
LEDs via its PWM dimming capability. Applying a PWM
signal (up to 500Hz) to the PWMD pin allows for control of
the brightness of the LED.
Each member of the MIC323x family employs peak current
mode control. Peak current mode control offers
advantages over voltage mode control in the following
manner. Current mode control can achieve a superior line
transient performance compared to voltage mode control
and through small signal analysis (not shown here),
current mode control is easier to compensate than voltage
mode control, thus allowing for a less complex control loop
stability design. Figure 2 shows the functional block
diagram.
Figure 2. MIC3230 Functional Block Diagram
Micrel, Inc. MIC3230/1/2
March 2011 9 M9999-030311-D
Power Topology
Constant Output Current Controller
The MIC323x family is peak current mode boost
controllers designed to drive high power LEDs. Unlike a
standard constant output voltage controller, the MIC323x
family has been designed to provide a constant output
current. The MIC323x family is designed for a wide input
voltage range, from 6V to 45V. In the boost configuration,
the output can be set from VIN up to 100V.
As a peak current mode controller, the MIC323x family
provides the benefits of superior line transient response as
well as an easier to design compensation.
This family of LED drivers features a built-in soft-start
circuitry in order to prevent start-up surges. Other
protection features include:
Current Limit (ILIMIT) - Current sensing for over current
and overload protection
Over Voltage Protection (OVP) - Output over voltage
protection to prevent operation above a safe upper
limit
Under Voltage Lockout (UVLO) UVLO designed to
prevent operation at very low input voltages
Setting the LED Current
The current through the LED string is set via the value
chosen for the current sense resistor, RADJ. This value can
be calculated using Equation 1:
Eq. (1)
ADJ
LED R
V
I25.0
=
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 the LED AC resistance (RLED – provided
by the LED manufacturer) plus the current sense resistor
(RADJ). The amount of allowable ripple through the LED
string is dependent upon the application and is left to the
designer’s discretion. This equation is shown in Equation
2:
Eq. (2) )( ADJLED
OUT
LED RR
V
IRIPPLE
+
Δ
Where
OUT
LED
OUT C
TDI
V
RIPPLE
××
=
Reference Voltage
The voltage feedback loop of the MIC323x uses an
internal reference voltage of 0.25V with an accuracy of
±3%. The feedback voltage is the voltage drop across the
current setting resistor (RADJ) as shown in Figure 1. When
in regulation the voltage at IADJ will equal 0.25V.
Output Over Voltage Protection (OVP)
The MIC323x provides an OVP circuitry in order to help
protect the system from an overvoltage fault condition.
This OVP point can be programmed through the use of
external resistors (R8 and R9 in Figure 1). A reference
value of 1.245V is used for the OVP. Equation 3 can be
used to calculate the resistor value for R9 to set the OVP
point.
Eq. (3) 1)245.1/(
8
9
=
OVP
V
R
R
LED Dimming
The MIC323x family of LED drivers can control the
brightness of the LED string via the use of pulse width
modulated (PWM) dimming. A PWM input signal of up to
500Hz can be applied to the PWM DIM pin (see Figure 1)
to pulse the LED string ON and OFF. It is recommended to
use PWM dimming signals above 120Hz to avoid any
recognizable flicker by the human eye. PWM dimming is
the preferred way to dim a LED in order to prevent
color/wavelength shifting, as occurs with analog dimming.
The output current level remains constant during each
PWMD pulse.
Oscillator and Switching Frequency Selection
The MIC323x family features an internal oscillator that
synchronizes all of the switching circuits internal to the IC.
This frequency is adjustable on the MIC3230 and MIC3231
and fixed at 400kHz in the MIC3232.
In the MIC3230/1, the switching frequency can be set by
choosing the appropriate value for the resistor, R1
according to Equation 4:
Eq. (4)
035.1
)(
7526
)(
=Ω
kHzF
kR
SW
FS
SYNC (MIC3230 Only)
Multiple MIC3230 ICs can be synchronized by connecting
their SYNC pins together. When synchronized, the
MIC3230 with the highest frequency (master) will override
the other MIC3230s (slaves). The internal oscillator of the
master IC will override the oscillator of the slave part(s)
and all MIC3230 will be synchronized to the same master
switching frequency.
The SYNC pin is designed to be used only by other
MIC3230s and is available on the MIC3230 only. If the
SYNC pin is being unused, it is to be left floating (open). In
the MIC3231, the SYNC pin is to be left floating (open).
Micrel, Inc. MIC3230/1/2
March 2011 14 M9999-030311-D
(see the current waveforms in Figure 5).
It can be difficult to find large inductor values with high
saturation currents in a surface mount package. Due to
this, the percentage of the ripple current may be limited
by the available inductor. It is recommended to operate
in the continuous conduction mode. The selection of L
described here is for continuous conduction mode.
Eq. (13)
PPin
IN
I
TDV
L
_
××
=
Using the nominal values, p14-we get:
H
A
sV
L
μ
μ
43
31.0
256.012 =
××
=
Select the next higher standard inductor value of 47µH.
Going back and calculating the actual ripple current
gives:
Eq. (13a) PP
nomnomIN
PPin A
uh
usv
L
TDV
I29.0
47
256.012
_
_=
××
=
××
=
The average input current is different than the RMS input
current because of the ripple current. If the ripple current
is low, then the average input current nearly equals the
RMS input current. In the case where the average input
current is different than the RMS, Equation 10 shows the
following:
Eq. (13b)
( )
(
)
12
2
_
2
max__max__
PPIN
RMSINAVEIN
I
II =
( ) ( )
AI AVEIN 64.112/29.064.1 22
max__ =
The Maximum Peak input current IL_PK can found using
equation 11:
AIII PPLAVEINPKL 78.15.0 max__max__max__ =
×
+=
The saturation current (ISAT) at the highest operating
temperature of the inductor must be rated higher than
this.
The power dissipated in the inductor is:
Eq. (13c) DCRIP RMSinINDUCTOR ×= 2
max__
Current Limit and Slope Compensation
Having calculated the IL_pk above, We can set the current
limit 20% above this maximum value:
AAI Limit
pkL 9.16.12.1
_=×=
The internal current limit comparator reference is set at
0.45V, therefore when 45.0
_
=
PINIS
V, the IC enters
current limit.
Eq. (14)
(
)
PKA VcsV PK +=45.0
Where PK
A
Vis the peak of the A
V waveform and
PK
Vcs is the peak of the Vcs waveform
Eq. (14a) CSpkLSLCRAMP RIDRI Limit
×
+××
=
_
45.0
To calculate the value of the slope compensation resistance,
RSLC, p14-we can use Equation 5:
(
)
SW
CSINOUT
SLC FAL
RVV
RMINMAX
××
×
=
μ
250
First p14-we must calculate R
CS, which is given below in
Equation 15:
Eq. (15)
( )
Limit
pkL
SW
MINMAX
CS
I
FL
DVINVOUT
R
_
max
45.0
+
×
×
=
Therefore;
( ) ( )
Ω=
+
×
×
=m
A
kHzH
vv
RCS 179
9.1
50047
50.0828
45.0
μ
Using a standard value 150m resistor for RCS, p14-we obtain
the following for R
SLC :
(
)
Ω=
××
Ω×
=511
50025047
150828
kHzAH
m
RSLC
μμ
Use the next higher standard value if this not a standard
value. In this example 511 is a standard value.
Check: Because p14-we must use a standard value for Rcs and
RSLC; Limit
pk_L
I may be set at a different level (if the calculated
value isn’t a standard value) and p14-we must calculate the
actual Limit
pk_L
I value (remember Limit
pk_L
Iis the same as
Limit
pk_in
I).
Rearranging Equation 14a to solve for Limit
pkL
I_:
CS
SLCRAMP
pkin R
DRI
ILimit
)45.0(
_
××
=
A
ua
ILimit
actualin 34.2
150.
)75.051125045.0(
_=
××
=
This is higher than the initial A9.1=I×2.1 max_PK_L limit
because p14-we have to use standard values for R
CS and for
RSLC. If Limit
actual_in
Iis too high than use a higher value for
RCS. The calculated value of RCS for a 1.9A current limit was
179m. In this example, p14-we have chosen a lower value
which results in a higher current limit. If p14-we use a higher
standard value the current limit will have a lower value. The
designer does not have the same choices for small valued
resistors as with larger valued resistors. The choices differ
from resistor manufacturers. If too large a current sense
resistor is selected, the maximum output power may not be
able to be achieved at low input line voltage levels. Make
sure the inductor will not saturate at the actual current limit
Limit
actual_in
I.
Perform a check at IIN=2.34Apk.
(
)
VmAAV PINIS 45.015034.251178.0250
_
=
Ω
×+
Ω
×
×
=
μ


Produktspezifikationen

Marke: Microchip
Kategorie: Nicht kategorisiert
Modell: MIC3231

Brauchst du Hilfe?

Wenn Sie Hilfe mit Microchip MIC3231 benötigen, stellen Sie unten eine Frage und andere Benutzer werden Ihnen antworten




Bedienungsanleitung Nicht kategorisiert Microchip

Bedienungsanleitung Nicht kategorisiert

Neueste Bedienungsanleitung für -Kategorien-