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PDF CAT3661 Data sheet ( Hoja de datos )
| Número de pieza | CAT3661 | |
| Descripción | 1-Channel Low-Power Quad-Mode LED Driver | |
| Fabricantes | ON Semiconductor | |
| Logotipo |  |
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CAT3661
1-Channel Low-Power LED
Driver
Description
The CAT3661 is a high efficiency low power fractional charge
pump that drives one LED with up to 5 mA of current. Soft−start
current limiting and short−circuit protection are optimized for use with
coin cell batteries.
Low noise input ripple and constant switching frequency allows the
use of small external ceramic capacitors. This makes the CAT3661
ideal for EMI sensitive applications. The charge pump supports a wide
range of input voltages from 2.0 V to 5.5 V.
The CAT3661 has a built−in circuitry to provide feedback to a
microcontroller of Open/Short LED and Low battery events. The Low
battery indicator trip point is internally fixed at 2.4 V. External
resistors can be added to raise or lower the trip voltage, if needed.
The device is packaged in the tiny 16−lead TQFN 3 mm x 3 mm
package with a max height of 0.8 mm.
The inclusion of a 1.33x fractional charge pump mode increases
device efficiency by up to 10% over traditional 1.5x tri−mode charge
pumps with no added external capacitors. The 1.33x charge pump with
two fly capacitors is a patented architecture exclusive to
ON Semiconductor.
Features
• Charge Pump: 1x, 1.33x, 1.5x, 2x
• Drives One LED up to 5 mA
• Optimized for Coin Cell Battery Operation
• Open/Short LED Fault Detection
• Adjustable Low Battery Detection
• Low Quiescent Current 150 mA Typical
• Power Efficiency up to 92%
• Low Noise Input Ripple in All Modes
• “Zero” Current Shutdown Mode
• Soft Start and Short Circuit Current Limiting
• Thermal Shutdown Protection
• 3 mm x 3 mm, 16−pad TQFN Package
• This Device is Pb−Free, Halogen Free/BFR Free and is RoHS
Compliant
Typical Applications
• Low Power LCD Display Backlight
• Low Power Handheld Device Backlight
http://onsemi.com
TQFN−16
HV3 SUFFIX
CASE 510AD
PIN CONNECTIONS
RSET
nFLTB
nFLTL
EN
1
C1−
C1+
C2+
C2−
(Top View)
See detailed description of the pins function on
page 8 of this data sheet.
MARKING DIAGRAM
JAAU
AXXX
YWW
JAAU = CAT3661HV3−GT2
A = Assembly Location
XXX = Last Three Digits of Assembly Lot Number
Y = Production Year (Last Digit)
WW = Production Week (Two Digits)
ORDERING INFORMATION
See detailed ordering and shipping information on page 2 of
this data sheet.
© Semiconductor Components Industries, LLC, 2014
August, 2014 − Rev. 2
1
Publication Order Number:
CAT3661/D
1 page  
CAT3661
TYPICAL CHARACTERISTICS
(VIN = 3 V, ILED = 3 mA, VF = 3 V, TAMB = 25°C, typical application circuit unless otherwise specified.)
225 140
2x 1.5x
200
1.5x 120
175
1.33x
100
1.33x, 2x
150
1x
125
−40
0
40 80 120
TEMPERATURE (°C)
Figure 7. Quiescent Current vs. Temperature
2.0
1.6
1.2
0.8
0.4
0
−0.4
−0.8
−1.2
−1.6
−2.0
2.0 2.5 3.0 3.5 4.0 4.5 5.0
INPUT VOLTAGE (V)
Figure 9. LED Current Change vs. Input
Voltage
100
90 1x
1.33x
1.5x
5.5
80
80
−40
0 40 80
TEMPERATURE (°C)
Figure 8. Switching Frequency vs.
Temperature
2.0
VF = 3 V
1.5
1.0
0.5
0
−0.5
−1.0
−1.5
−2.0
−40
0 40 80
TEMPERATURE (°C)
Figure 10. LED Current Change vs.
Temperature
100
90
1.33x
80
1.5x
120
120
70 70
60
2x
50
40 VF = 3 V
4.5 4.0 3.5 3.0 2.5 2.0
INPUT VOLTAGE (V)
Figure 11. Efficiency vs. Input Voltage
60
2x
50
VF = 3 V
40
3.2 3.0 2.8 2.6 2.4 2.2 2.0
INPUT VOLTAGE (V)
Figure 12. Efficiency vs. Lithium Coin Cell
Voltage
http://onsemi.com
5
5 Page 
CAT3661
Protection Mode
Open LED Protection
An LED is deemed open circuit if the LED current sink is
unable to regulate the LED channel to the programmed
current for greater than 2 ms. The driver will sense this
condition and the nFLTL pin will be driven low. The device
will be placed into a standby−mode until the Open LED
condition is removed or the device is re−enabled (EN goes
low then high again) at which point the Open LED condition
will be evaluated.
Short LED Protection
An LED is deemed to be short circuit if the difference
between VOUT pin and LED pin is less than 1.0 V when the
programmed current is driven in the channel for greater than
2 ms. If this is the case, then the LED sink is turned off and
a 5 mA test current is placed in the channel. The nFLTL pin
is driven low. Once the short condition is removed normal
operation will resume and nFLTL will be floated high.
When the device is shutdown (EN low), the nFLTL pin
will float high to ‘zero’ current state.
Input Current Limiting
The charge pump contains an input current limit circuit
that limits the current through the input pin. The current is
limited to 1000 times (GI_MAX) the current flowing in
RSET. Use the following formula:
IMAX
+
0.6 V
RSET
1000
The input current limit insures the battery is never loaded
with more than 3.3 times the LED current during a short
circuit condition, Charge Pump startup condition or charge
pump mode change. The device will only ever use a
maximum of 2 times the programmed LED current plus
quiescent operating current when in normal 2x mode of
operation.
Lithium coin cell batteries have high internal resistances
so a robust current limit is a very important feature of the
device to prevent large voltage droops from triggering
device resets during operation of the CAT3661.
Over Voltage, Over Temperature Protection
As soon as VOUT is pumped above 4.5 V, the driver will
stop advancing modes if the LED sink is not in regulation.
This indicates a possible Open LED condition and stops the
device from seeing excessive voltages on the output pin
greater than the absolute maximum ratings for VOUT. An
additional fail safe over−voltage detector prevents the
VOUT output from ever exceeding 6.5 volts.
If the die temperature exceeds +150°C, the driver will
enter a thermal protection shutdown mode and the LED will
be turned off. The nFLTL pin will be driven low. Once the
device temperature drops by about 20°C, the device will
resume normal operation and nFLTL will be floated high.
External Components
The driver requires four external 1 mF ceramic capacitors
for decoupling input, output, and for the charge pump “fly”
capacitors. Capacitors type X5R and X7R are recommended
for the LED driver application. In all charge pump modes,
the input current ripple is kept very low by design and an
input bypass capacitor of 1 mF is sufficient. In 1x mode, the
device operates in linear mode and does not introduce
switching noise back onto the supply.
LED Selection
LEDs with forward voltages (VF) ranging from 1.3 V to
4.2 V may be used. Selecting LEDs with lower VF is
recommended in order to improve the efficiency by keeping
the driver in 1x mode longer as the battery voltage decreases.
For example, if a white LED with a VF of 3.3 V is selected
over one with VF of 3.5 V, the driver will stay in 1x mode to
a lower supply voltage of 0.2 V. This helps improve the
efficiency and extends battery life.
http://onsemi.com
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet CAT3661.PDF ] | |
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