LX1995
TM
®
Miniature LED Driver
P
RODUCTION
D
ATA
S
HEET
DESCRIPTION
KEY FEATURES
< 1µA Shutdown Current
> 85% Maximum Efficiency
Efficient at Low Current Levels
< 70µA Quiescent Supply
Current in Operating Mode
V
IN
Range 1.6V to 5.5V
Logic Controlled Shutdown
Dimming Options: PWM or
Varying DC Voltage
Tiny 5-Pin TSOT Package
Smallest External Components
APPLICATIONS
IMPORTANT:
For the most current data, consult
MICROSEMI’s
website:
http://www.microsemi.com
V
BAT
= 2.0V to 5.0V
bs
IN
O
ol
e
PRODUCT HIGHLIGHT
SW
The Microsemi LX1995-x is a
miniature LED driver with integrated
drivers. It is designed to drive white
or color LEDs in portable display
applications. The LX1995-x is an
adjustable step-up boost converter.
The LX1995-x can switch up to 2MHz
allowing designers to use a low cost,
small inductor and filter capacitor.
The driver supports a wide input
voltage range (1.6V to 5.5V) with
efficiency greater than 85% and can
start up at 1.6V input. The LX1995-x
is a low cost, high efficiency LED
driver. The design is based on a
pseudo-hysteretic pulse frequency
modulation topology.
In portable
battery applications the LX1995-x
offers high system efficiency with low
quiescent current: in operation I
Q
is <
70µA and in standby I
Q
is < 1µA.
LX1995
FB
GND
ON OFF
SHDN
te
Pagers
Wireless Phones
PDAs
LED Driver
Digital Camera Displays
GPS Receivers
The LX1995-x output current is
programmable using an external current
sense resistor in series with LEDs. This
configuration provides a feedback to the
FB pin which maintains constant output
current independent of input voltage
and LED forward voltage (VF). LED
dimming is accomplished using a PWM
signal or varying DC voltage methods.
The LX1995-x is available in the 5-
Pin TSOT and SOT-23 package. The
LX1995-1 can drive up to 6 LEDs
(switching current is 325mA). The
LX1995-2 can drive up to 10 LEDs
(switching current is 500mA).
WWW .
Microsemi
.C
OM
LX1995
LX1995
PACKAGE ORDER INFO
T
A
(°C)
-40 to 85
-40 to 85
Switch
Current
325mA
500mA
SG
Plastic TSOT
5-Pin
RoHS Compliant / Pb-free
SE
Plastic SOT-23
5-Pin
LX1995-1CSE
LX1995-2CSE
RoHS Compliant / Pb-free Transition DC: 0503
LX1995-1CSG
LX1995-2CSG
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1995-1CSG-TR)
Copyright
©
2000
Rev. 1.1, 2005-07-07
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
LX1995
TM
®
Miniature LED Driver
P
RODUCTION
D
ATA
S
HEET
ABSOLUTE MAXIMUM RATINGS
PACKAGE PIN OUT
WWW .
Microsemi
.C
OM
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal
.
THERMAL DATA
ol
e
207°C/W
191°C/W
FUNCTIONAL PIN DESCRIPTION
Description
SG
SE
Plastic TSOT 5-Pin
THERMAL RESISTANCE
-
JUNCTION TO
A
MBIENT
,
θ
JA
Plastic SOT-23 5-Pin
THERMAL RESISTANCE
-
JUNCTION TO
A
MBIENT
,
θ
JA
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
θ
JA
).
The
θ
JA
numbers are guidelines for the thermal performance of the device/pc-board system. All of the
above assume no ambient airflow.
Name
SW
GND
FB
O
SHDN
IN
bs
Common terminal for ground reference.
Inductor Switching Connection – Internally connected to the drain of a 28V N-channel MOSFET. SW is high
impedance in shutdown.
Feedback Input – Connect to a current sense resistor between the load and GND to set the maximum output
current. FB pin is regulated to 320mV.
Active-Low Shutdown Input – A logic low shuts down the device and reduces the supply current to <1µA.
Connect
SHDN
to V
CC
for normal operation.
te
SW
1
5
Supply Input Voltage ........................................................................-0.3V to 7.0V
Feedback Peak Pulse Input Voltage (V
FB
) ..............................-0.3V to V
IN
+ 0.3V
Shutdown Input Voltage (V
SHDN
) ...........................................-0.3V to V
IN
+ 0.3V
Switch Voltage (V
SW
) ........................................................................-0.3V to 30V
Switch Current (I
SW
) ...................................................................................500mA
Operating Temperature Range .........................................................-40°C to 85°C
Maximum Operating Junction Temperature ................................................ 125°C
Storage Temperature Range...........................................................-65°C to 150°C
Peak Package Solder Reflow Temp. (40 second max. exposure) ... 260°C (+0, -5)
SW
1
5
IN
GND
2
FB
3
4
SHDN
SG P
ACKAGE
(Top View)
IN
GND
2
FB
3
4
SHDN
SE P
ACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
P
ACKAGE
D
ATA
P
ACKAGE
D
ATA
Unregulated IC Supply Voltage Input – Input range from +2.0V to +5.5V. Bypass with a 1µF or greater capacitor
for low voltage operation.
Copyright
©
2000
Rev. 1.1, 2005-07-07
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
LX1995
TM
®
Miniature LED Driver
P
RODUCTION
D
ATA
S
HEET
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, the following specifications apply over the operating ambient
1
temperature 0°C
≤
T
A
≤
70°C except where
otherwise noted and the following test conditions:
V
IN
= 3V, V
SHDN
= V
IN
. Unless where indicated, these parameters apply to both the
LX1995-1 and LX1995-2 part versions.
Parameter
Operating Voltage
Minimum Start-up Voltage
Start-up Voltage Temperature
Coefficient
Quiescent Current
FB Threshold Voltage
FB Input Bias Current
Shutdown Input Bias Current
Shutdown Low Input Voltage
Shutdown High Input Voltage
Switch Peak Current
Switch Peak Current
Minimum Switch Off-Time
Switch Pin Leakage Current
Note:
1.
2.
WWW .
Microsemi
.C
OM
Symbol
V
IN
V
SU
k
VST
I
Q
V
FB(TH)
I
FB
I
SHDN
V
SHDN
I
PEAK
I
PEAK
t
OFF
I
LEAK
T
A
= +25°C
Test Conditions
Min
1.6
LX1995-x
Typ
Max
5.5
1.6
-2
70
0.2
320
100
0.5
352
10
100
0.6
400
600
Units
V
V
mV/°C
µA
mV
nA
nA
V
mA
mA
ns
µA
Guaranteed; not tested
Not switching
V
SHDN
< 0.4V
Not Switching, V
FB
= 400mV
V
SHDN
= 0V
Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature.
Functionality over the -40°C to +85°C operating temperature range is assured by design, characterization, and correlation.
ol
e
SIMPLIFIED BLOCK DIAGRAM
Control
Logic
Driver
L= 47µH; LX1995-1
L= 47µH; LX1995-2
T
A
= +25°C; V
FB
< V
FB(TH)
V
SW
= 28V
FB
GND
bs
Bias
Reference
O
SHDN
te
288
-10
-100
1.4
250
400
325
500
300
0.23
SW
V
E
LECTRICALS
E
LECTRICALS
IN
Figure 1 –
Simplified Block Diagram
Copyright
©
2000
Rev. 1.1, 2005-07-07
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3
LX1995
TM
®
Miniature LED Driver
P
RODUCTION
D
ATA
S
HEET
APPLICATION CIRCUITS
WWW .
Microsemi
.C
OM
L
1
V
BAT
= 2.0V to 5.0V
10µH
1206 Case Size
D
1
C
1
0.1µF
IN
SW
100Hz to 1kHz
SHDN
GND
ol
e
L
1
D
1
10µH
1206 Case Size
1
0.1µF
Figure 2 –
Typical Bust Mode Dimming LED Driver Application
V
BAT
= 2.0V to 5.5V
bs
IN
LX1995
FB
GND
ON OFF
SHDN
O
te
FB
1
15
Ω
LX1995
R
C
SW
100kΩ
R
3
17.4kΩ
R
2
A
PPLICATIONS
A
PPLICATIONS
V
DC
= 0V to 2.0V
I
LED
= 0mA to 20mA
17.4
Ω
R
1
Figure 3 –
Analog Voltage Dimming LED Driver Application
The component values shown are only examples for a working system. Actual values will vary greatly depending on
desired parameters, efficiency, and layout constraints.
Copyright
©
2000
Rev. 1.1, 2005-07-07
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
LX1995
TM
®
Miniature LED Driver
P
RODUCTION
D
ATA
S
HEET
APPLICATION CIRCUITS
WWW .
Microsemi
.C
OM
L
1
V
BAT
= 2.0V to 5.0V
10µH
1206 Case Size
D
1
1
0.1µF
C
IN
SW
LX1995
ON OFF
SHDN
GND
V
PWM
= 3.3V
DC = 10% to 90%
I
LED
= 0mA to 20mA
ol
e
>10kHz
4
9.09kΩ
0.1µF
Figure 4 –
PWM to Analog Voltage Dimming LED Driver Application
L
1
V
BAT
= 2.0V to 5.0V
bs
SW
IN
10µH
1206 Case Size
On
LX1995
FB
320mV
Off
SHDN
GND
O
V
CC
2R
R
R
A
= (0.64 x R) / V
CC
LSB
V
CC
MSB
te
FB
R
C
2
3
90.9kΩ
R
2
11.2kΩ
R
1
15
Ω
R
C
1
.1µF
2R - R
A
R
A
R
CS
A
PPLICATIONS
A
PPLICATIONS
MSB
1
1
0
0
LSB
1
0
1
0
I
LED
0.25 x I
MAX
0.50 x I
MAX
0.75 x I
MAX
I
MAX
Rcs = (0.32 x R) / {[R - (0.375 x R
A
)] x I
MAX
}
Figure 5 –
Binary Dimming LED Driver Application
The component values shown are only examples for a working system. Actual values will vary greatly depending on desired parameters, efficiency, and layout
constraints.
Copyright
©
2000
Rev. 1.1, 2005-07-07
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
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