A8515GLPTR-T Allegro Microsystems Inc, A8515GLPTR-T Datasheet - Page 12

• Manufacturer Part Number: A8515GLPTR-T
• Description: Backlight Driver For Medium Size LCDs
• Manufacturer: Allegro Microsystems Inc

Specifications of A8515GLPTR-T

• Constant Current: *
• Constant Voltage: *
• Internal Driver: *
• Type - Primary: *
• Type - Secondary: *
• Mounting Type: Surface Mount
• Topology: *
• Number Of Outputs: *
• Frequency: *
• Voltage - Supply: *
• Voltage - Output: *
• Package / Case: 16-TSSOP Exposed Pad, 16-eTSSOP, 16-HTSSOP
• Operating Temperature: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

A8515
The LED pin detection voltage thresholds are as follows:
All unused pins should be connected with a 1.54 kΩ resistor to
GND, as shown in figure 5. The unused pin, with the pull-down
resistor, will be taken out of regulation at this point and will not
contribute to the boost regulation loop.
4A. An LED detect occurring when both LED pins are selected to be used;
shows LED1 (ch1, 500 mV/div.), LED2 (ch2, 500 mV/div.), ISET (ch3,
1 V/div.), and PWM/EN (ch4, 5 V/div.) pins, 500 μs/div.
C1
C2
C3
C4
LED Pin Voltage
<170 mV
150 mV
325 mV
LED Pin Status
LED pin in use
Short-to-GND
Not used
PWM/EN
t
LED1
LED2
ISET
4C. Example with one LED shorted to GND. The IC will not proceed with power-
up until the shorted LED pin is released, at which point the LED is checked to
see if it is being used ; shows LED1 (ch1, 500 mV/div.), LED2 (ch2, 500 mV/div.),
ISET (ch3, 1 V/div.), and PWM/EN (ch4, 5 V/div.) pins, 1 ms/div.
.
C1
C2
C3
C4
LED removed from operation
Power-up is halted
Pin shorted
LED detection period
Action
None
Wide Input Voltage Range, High Efficiency
PWM/EN
t
LED1
LED2
ISET
Figure 5. Channel select setup: (left) using only channel LED1,
(right) using both channels.
4B. Example with LED2 pin not being used; the detect voltage is
about 150 mV; shows LED1 (ch1, 500 mV/div.), LED2 (ch2, 500 mV/div.),
ISET (ch3, 1 V/div.), and PWM/EN (ch4, 5 V/div.) pins, 500 μs/div.
C1
C2
C3
C4
Short removed
Fault Tolerant LED Driver
GND
A8515
LED1
LED2
1.54 kΩ
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
PWM/EN
t
LED1
LED2
ISET
GND
A8515
LED1
LED2
LED detection period
12