Eutech EUP3595 Parallel white-led driver Datasheet

EUP3595
Parallel White-LED Driver
DESCRIPTION
FEATURES
The EUP3595 is a parallel white-LED driver with four
matched current outputs. It can supply a total output
current of 100mA over an input voltage range of 3.0V to
5.5V. The amount of constant current sourced to the
outputs is user selectable using one external sense
resistor.
EUP3595 typically draws 0.01µA when placed in
shutdown, and 180µA when operating in the no-load
condition. If any of the outputs are not used, leave the
pin(s) unconnected.
Brightness can be controlled by PWM techniques or by
adding a DC voltage. A PWM signal can be applied to
the EN/PWM pin to vary the perceived brightness of the
LED.
The EUP3595 uses an active-high enable level. The
EUP3595 is available in TDFN-8 and TSSOP-8 package.
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APPLICATIONS
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Typical Application Circuit
Figure 1.
DS3595 Ver1.0
Feb. 2007
1
Regulated IOUT With ± 0.3% Matching Between
Constant Current Outputs
Drives One, Two, Three or Four White LED’s with
No Ballast Resistors
3.0V to 5.5V Input Voltage
Up to 100mA Output Current
Active-High Enable
Very Small Solution Size
Very Low Shutdown Current (0.01µA typical)
Available in TDFN-8 ,TSSOP-8 Package
RoHS Compliant and 100% Lead(Pb)-Free
Portable devices using white or blue LEDs with
display and backlight or front-light
Keypad LEDs
Strobe LEDs
EUP3595
Block Diagram
Figure 2.
Pin Configurations
Package
Type
Pin
Package
Type
Configurations
TDFN-8
Pin
Configurations
TSSOP-8
Pin Description
PIN
TDFN-8
TSSOP-8
VIN
1
1
Input Voltage
GND
2
2
Ground
EN/PWM
3
3
ISET
4
4
LED1-4
8-5
8-5
Active-High Enable Input – There is no internal pull-down resistor.
Current Set Input- The resistor value tied between this pin and ground sets the
output current.
Current Source Outputs 1- 4 - Connect directly to LED’s
DS3595 Ver1.0
Feb. 2007
DESCRIPTION
2
EUP3595
Ordering Information
Order Number
Package Type
Marking
Operating Temperature range
EUP3595JIR1
TDFN-8
-40 °C to 85°C
EUP3595QIR1
TSSOP-8
xxxx
3595A
xxxx
3595A
EUP3595- □ □ □ □
Lead Free Code
1: Lead Free 0: Lead
Packing
R: Tape & Reel
Operating temperature range
I: Industry Standard
Package Type
J: TDFN-8
Q: TSSOP-8
DS3595 Ver1.0
Feb. 2007
3
-40 °C to 85°C
EUP3595
Absolute Maximum Ratings
„
„
„
„
„
„
„
„
„
VIN --------------------------------------------------------------------------------- -0.3V to 6V max
EN/PWM----------------------------------------------------------- -0.3V to (VIN+0.3V) w/ 6 max
Continuous Power Dissipation ------------------------------------------------ Internally Limited
TDFN-8L , 3 × 3,θJA --------------------------------------------------------------------------- 50°C/W
TSSOP-8L , θJA ------------------------------------------------------------------------------ 70°C/W
Junction Temperature (TJ ) ------------------------------------------------------------------- 150°C
Storage Temperature Range ------------------------------------------------------- -65°C to 150°C
Lead Temp (Soldering, 5sec) ----------------------------------------------------------------- 260°C
ESD Rating Human Body Model -------------------------------------------------------------- 2kV
Operating Conditions
„
„
Input Voltage (VIN) ------------------------------------------------------------------ 3V to 5.5V
Ambient Temperature (TA) --------------------------------------------------------- -40°C to 85°C
Electrical Characteristics
Limits in standard typeface and typical values apply for TA=25°C. Limits in boldface type apply over the operating
junction temperature range (-40°C~+85°C). Unless otherwise specified: VIN=5V, VLEDX=3.6V, RSET=7.5k,
V(EN/PWM)=VIN.
Symbol
ILEDX
Parameter
LED Current
Conditions
3.0V ≤ VIN ≤ 5.5V
2.0V ≤ VLEDX ≤ (VIN-0.4V)
RSET=7.5k
EUP3595
Min
Typ Max.
14.3
(-10%)
ILEDX-MATCH Current Matching Between Any
Two Outputs
VSET
ILEDX/ISET
Output Current to Current
Set Ratio
VHR
Current Source Headroom
Voltage
IQ
1.06
(-8%)
ISET Pin Voltage
Quiescent Supply Current
ISHUT-DOWN Shutdown Supply Current
Unit
15.8
17.3
(+10%)
mA
±0.3
±1
%
1.18
1.3
(+8%)
V
320
440
mV
130
220
mV
175
285
100
ILED=95% × ILED(nom), RSET= 4.7K
(ILED(nom) approx. 25mA)
ILED=95% × ILED(nom), RSET= 12K
(ILED(nom) approx. 10mA)
ILED=0mA, RSET=Open
ILED=0mA, RSET=7.5k
325
EN/PWM=0
0.01
uA
1
uA
VEN-H
EN/PWM Input Logic High
3.0V ≤ VIN ≤ 5.5V
1
VIN
V
VEN-L
EN/PWM Input Logic Low
3.0V ≤ VIN ≤ 5.5V
0
0.5
V
DS3595 Ver1.0
Feb. 2007
4
EUP3595
Typical Operating Characteristics
DS3595 Ver1.0
Feb. 2007
5
EUP3595
Application Information
Brightness Control
Enable/Shutdown
When the voltage on the active-high-logic enable pin
is low, the EUP3595 will be in shutdown. While
disabled, the EUP3595 typically draws 0.01µA. There
is no internal pull-up or pull-down on the PWM pin
of the EUP3595, Do not let PWM pin floating.
Output Current Capability
The EUP3595 is capable of providing up to 25mA of
current to each of the four outputs given an input
voltage of 3.0V to 5.5V. The outputs have a typical
current matching of ± 0.3% between adjacent sources.
An external resistor can be used to set the output
current, as approximated with the following the
equation:
(1)Using a PWM Signal to EN/PWM Pin
Brightness control can be implemented by pulsing a
signal at the PWM pin. The RSET value should be
selected using the RSET equation. LED brightness is
proportional to the duty cycle (D) of the PWM signal.
For linear brightness control over the full duty cycle
adjustment range, the PWM frequency (f) should be
limited to accommodate the turn-on time (TON = 20µs)
of the de- vice.
D ∗ (1 / f ) > TON
f MAX = D MIN / TON
If the PWM frequency is much less than 100Hz,
flicker may be seen in the LEDs. For the EUP3595,
zero duty cycle will turn off the LEDs and a 50%
duty cycle will result in an average ILED being half of
the programmed LED current. For example, if RSET is
set to program 15mA, a 50% duty cycle will result in
an average ILED of 7.5mA, LED being half the
programmed LED current. RSET should be chosen not
to exceed the maximum current delivery capability of
the device.
R SET = 100 × (1.18 V / I LEDX )
In order for the output currents to be regulated
properly, sufficient headroom voltage (VHR) must be
present. The headroom voltage refers to the minimum
amount of voltage that must be present across the
current source in order to ensure the desired current is
realizable. To ensure the desired current is obtained,
apply the following equations to find the minimum
input voltage required:
(2)Using a DC Voltage Added to RSET
Using an analog input voltage VADJ via a resister RADJ
connects to the RSET pin can also be used to achieve
setting LED current. Figure 3 shows this application
circuit. For this application the LED's current can be
derived from the following Equation. Figure 4 and
table 2 shows the relation between VADJ and ILED of a
typical application example, where the VADJ from 0 to
2.5V, RSET equals 11.5kΩ and RADJ equals 12.5kΩ.
VIN − VLEDX ≥ VHR
VLEDX is the diode forward voltage, and VHR is
defined by the following equation:
VHR = K HR × (0.95 × I LEDX )
ILEDX is the desired diode current, and kHR, typically
15mV/mA in the EUP3595, is a proportionality
constant that represents the ON-resistance of the
internal current mirror transistors. For worst-case
design calculations, using a kHR of 20mV/mA is
recommended. (Worst-case recommendation accounts
for parameter shifts from part-to-part variation and
applies over the full operating temperature range).
Changes in headroom voltage from one output to
the next, possible with LED forward voltage
mismatch, will result in different output currents and
LED brightness mismatch. Thus, operating the
EUP3595 with insufficient headroom voltage across
all current sources should be avoided.

 1
1
+
I LED = 100 × 1.18 × 
 R SET R ADJ

 VADJ 
 −

 R ADJ 
Table 1. ILEDX, RSET and VHR-MIN
kHR= 20 mV/mA (worst-case)
IOUT
RSET
VHEADROOM
10mA
15mA
25mA
12kΩ
7.5kΩ
4.7kΩ
200mV
300mV
500mV
DS3595 Ver1.0
Feb. 2007
Figure3. The Application Circuit of Brightness
which Uses a DC Voltage Into RSET
6
EUP3595
With this configuration, two parallel current sources
of equal value provide current to each LED. RSET
should therefore be chosen so that the current through
each output is programmed to 50% of the desired
current through the parallel connected LEDs. For
example, if 30mA is the desired drive current for 2
parallel connected LEDs, RSET should be selected so
that the current through each of the outputs is 15mA.
Other combinations of parallel outputs may be
implemented in similar fashions, such as in Figure 6.
Figure4. EUP3595 LED Current Setting Example
Which Using a DC Voltage to RSET
Table 2. The LED Current vs VADJ With
RADJ=12.5KΩ and RSET=11.5KΩ
VADJ(V)
0
0.2
0.4
0.6
0.8
1
1.2
ILED(mA)
19.7
18.1
16.5
14.9
13.3
11.7
10.1
VADJ(V)
1.4
1.6
1.8
2
2.2
2.4
2.5
ILED(mA)
8.5
6.9
5.3
3.7
2.1
0.5
0
LED Selection
The EUP3595 is designed to drive white-LEDs with a
typical forward voltage of 3.0V to 4.0V. The maximum
LED forward voltage that the EUP3595 can accommo
-date is highly dependant upon VIN and ILEDX (See the
section on Output Current Capability for more
information on finding maximum VLEDX.) For
applications that demand color and brightness
matching, care must be taken to select LEDs from the
same chromaticity group. Forward current matching is
assured over the LED process variations due to the
constant current outputs of the EUP3595.
Figure 6. One Parallel Connected LED
Connecting outputs in parallel does not affect internal
operation of the EUP3595 and has no impact on the
Electrical Characteristics and limits previously
presented. The available diode output current,
maximum diode voltage, and all other specifications
provided in the Electrical Characteristics table apply
to parallel output configurations, just as they do to the
standard 4-LED application circuit.
Power Consumption
It is recommended that power consumed by the
circuit (VIN × IIN) be evaluated rather than power
efficiency. Figure 7 shows the power consumption of
the EUP3595 Typical Application Circuit.
Parallel LEDx Outputs for Increased
Current Drive
Outputs LED1 through LED4 may be connected
together in any combination to drive higher currents
through fewer LEDs. For example in Figure 5,
outputs LED1 and LED2 are connected together to
drive one LED while LED3 and LED4 are connected
together to drive a second LED.
Figure 5. Two Parallel Connected LEDs
DS3595 Ver1.0
Feb. 2007
Figure 7. 4LEDs, LED VF=2.7V, ILED=15mA
7
EUP3595
Power Dissipation
The maximum allowable power dissipation that this
package is capable of handling can be determined as
follows:
PDMax = (TJMax − TA ) / θ JA
Where T is the maximum junction temperature, T is the
ambient temperature, and θJA is the junction
-to-ambient thermal resistance of the specified package.
The EUP3595 come in the TDFN-8 package that has a
junction-to-ambient thermal resistance (θJA)equal to
50℃/W.This value of θJA is highly dependant upon
the layout of the PC board. The actual power dissipated
by the EUP3595 follows the equation:
PDISS = (VIN × I IN ) − N (VLEDX × I LEDX
)
Where N equals the number of active outputs, VLEDX is
the LEDX LED forward voltage, and ILEDX is the current
supplied to the LEDX diode by the EUP3595. Power
dissipation must be less than that allowed by the
package. Please refer to the Absolute Maximum Rating
of the EUP3595.
Input Capacitor Selection
The EUP3595 is designed to run off of a fixed input
voltage. Depending on the stability and condition of
this voltage rail, it may be necessary to add a small
input capacitor to help filter out any noise that may be
present on the line. In the event that filtering is needed,
surface mount multi-layer ceramic capacitors are
recommended. These capacitors are small and
inexpensive. A capacitance of 0.1µF is typically
sufficient.
DS3595 Ver1.0
Feb. 2007
8
EUP3595
Packaging Information
TDFN-8
SYMBOLS
A
A1
b
D
D1
E
E1
e
L
DS3595 Ver1.0
Feb. 2007
MILLIMETERS
MIN.
MAX.
0.70
0.80
0.00
0.05
0.20
0.40
2.85
3.15
2.30
2.85
3.15
1.50
0.65
0.25
0.45
9
INCHES
MIN.
0.028
0.000
0.008
0.112
MAX.
0.031
0.002
0.016
0.124
0.090
0.112
0.124
0.059
0.026
0.010
0.018
EUP3595
TSSOP-8
SYMBOLS
A
A1
b
D
E
E1
e
L
DS3595 Ver1.0
Feb. 2007
MILLIMETERS
MIN.
MAX.
1.20
0.00
0.15
0.19
0.30
3.00
6.20
6.60
4.40
0.65
0.45
0.75
10
INCHES
MIN.
0.000
0.007
MAX.
0.048
0.006
0.012
0.118
0.244
0.260
0.173
0.026
0.018
0.030
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