LED7707TR STMicroelectronics, LED7707TR Datasheet - Page 15
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LED7707TR
Manufacturer Part Number
LED7707TR
Description
IC LED DRIVR WHT BCKLT 24-VFQFPN
Manufacturer
STMicroelectronics
Type
Backlight, White LEDr
Datasheet
1.LED7707TR.pdf
(47 pages)
Specifications of LED7707TR
Topology
PWM, Step-Up (Boost)
Number Of Outputs
6
Internal Driver
Yes
Type - Primary
Backlight
Type - Secondary
White LED
Frequency
250kHz ~ 1MHz
Voltage - Supply
4.5 V ~ 36 V
Voltage - Output
36V
Mounting Type
Surface Mount
Package / Case
24-VFQFN, 24-VFQFPN
Operating Temperature
0°C ~ 85°C
Current - Output / Channel
85mA
Internal Switch(s)
Yes
High Level Output Current
85 mA
Operating Supply Voltage
4.5 V to 36 V
Maximum Supply Current
1 mA
Maximum Power Dissipation
2.3 W
Maximum Operating Temperature
+ 150 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
- 40 C
For Use With
497-10044 - BOARD EVAL LCD BACKLIGHT LED7707
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Efficiency
-
Lead Free Status / Rohs Status
Details
Other names
497-8492-2
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LED7707TR
Manufacturer:
ST
Quantity:
12 000
Company:
Part Number:
LED7707TR
Manufacturer:
STMicroelectronics
Quantity:
10 000
LED7707
Equation 4
In addition, when the FSW pin is tied to AVCC, the LED7707 uses a default 660 kHz fixed
switching frequency, allowing to save a resistor in minimum component-count applications.
Figure 10. Multiple device synchronization
The FSW pin can also be used as synchronization input, allowing the LED7707 to operate
both as master or slave device. If a clock signal with a 220 kHz minimum frequency is
applied to this pin, the device locks synchronized. The signal provided to the FSW pin must
cross the 270 mV threshold in order to be recognized. The minimum pulse width which
allows the synchronizing pulses to be detected is 270 ns. An Internal time-out allows
synchronization as long as the external clock frequency is greater than 220 kHz.
Keeping the FSW pin voltage lower than 270 mV for more than 4.5 µs results in a stop of the
device switching activity. Normal operation is resumed as soon as FSW rises above the
mentioned threshold and the soft-start sequence is repeated.
The SYNC pin is a synchronization output and provides a 35 % (typ.) duty-cycle clock when
the LED7707 is used as master or a replica of the FSW pin when used as slave. It is used to
connect multiple devices in a daisy-chain configuration or to synchronize other switching
converters running in the system with the LED7707 (master operation). When an external
synchronization clock is applied to the FSW pin, the internal oscillator is over-driven: each
switching cycle begins at the rising edge of clock, while the slope compensation (
ramp starts at the falling edge of the same signal. Thus, to prevent sub-harmonic instability
(see
duty-cycle when the boost converter is working in continuous-conduction mode (CCM) in
order to assure that the slope compensation is effective (starts with duty-cycle lower than
40%)
Section 5.1.6
R
FSW
FSW
), the external synchronization clock is required to have a 40 % maximum
AVCC
LED7707
MASTER
SGND
SYNC
R
FSW
=
F
2
SW
5 .
FSW
LED7707
SLAVE
SYNC
Operation description
SGND
SYNC
Figure 11
Sync Out
AM00587v1
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