tm
TE
CH
Preliminary
T8309AD
PWM Control 1500mA Step-Down Converter
Built-sensitive switch hysteresis control function
FEATURES
• Wide Input Voltage Range: 4.5V to 30V
• LED Output Current Up to 1500mA
• Soft-start
• Single pin on/off and brightness control
using DC voltage or PWM
• High efficiency (up to 97%)
• CCTV IR LED Driver add CDS control
Built-sensitive switch hysteresis control
function
• Up to 1MHz switching frequency
• Typical 5% output current accurac
y
• SOP-8 Lead-free Package
GENERAL DESCRIPTION
The T8309AD is a continuous mode inductive
step-down converter, designed for driving
single or multiple series connected LEDs
efficiently from a voltage source higher than
the LED voltage. The device operates from an
input supply between 4.5V and 30V and
provides an externally adjustable output
current of up to 1500mA. Depending upon
supply voltage and external components, this
can provide up to 24 watts of output power.
The T8309AD includes the output switch and
a high-side output current sensing circuit,
which uses an external resistor to set the
nominal average output current. The T8309AD
is available in SOP-8 Lead-free package.
Applications
• LED/Display Back Light Driver
• Lightings
• Portable Communication Devices
• Handheld Electronics
• CCTV IR LED Driver
PART NUMBER EXAMPLES
PART NO.
T8309AD
PACKAGE
SOP-8
TM Technology, Inc. reserves the right
to change products or specifications without notice.
P. 1
Publication Date: Sep. 2014
Revision:C
tm
TE
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Preliminary
T8309AD
PIN ARRANGEMENT(Top view)
PIN DESCRIPTION
Symbol
LX
GND
CDI
CDO
ISENSE
VIN
SOP-8
3,4
5.6
1
2
8
7
Drain of NMOS switch
Ground
CDS Application Input &Enable control signal, H: Active, L: Power
Down
，
CDI longer than 3 seconds, to maintain a high voltage
Enable Application OutInput for IR Cut Driver
Connect resistor Rs from this pin to VIN to define nominal average output
current I
OUTnom
=0.1/Rs
Input voltage (4.5V to 30V).
Decouple to ground with 47uF or higher X7R ceramic capacitor close to
device.
Description
TM Technology, Inc. reserves the right
to change products or specifications without notice.
P. 2
Publication Date: Sep . 2014
Revision:C
tm
TE
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Preliminary
T8309AD
Parameter
Symbol
VIN
Value
-0.3 to +40
-5 to +0.3
-0.3 to +6
T
j
TA
T
LEAD
T
S
SOP-8
SOP-8
-40 to 150
-40 to 105
300
-65 to +150
0.8
50
Unit
V
V
V
℃
℃
℃
℃
W
℃
/W
ABSOLUTE MAXIMUM RATINGS
Voltage on input pin relative to GND
ISENSE pin Voltage
CDI pin
＆CDO
pin Voltage
Operating junction Temperature Rang
Operating Temperature Rang
Maximum Soldering Temperature (at lead, 10sec)
Storage Temperature Rang
Power Dissipation, PD @ TA=25℃
Package Thermal Resistance,
θ
JA
Electrical Characteristics
(TA=-40 to 105
℃
unless otherwise noted. Typical values are at TA=25
℃
, VDD=24V)
Symbol
VIN
U
VLO
V
IRU
V
IRD
I
QOff
I
QOn
Input voltage
Under Voltage lock out
Internal regulator start-up threshold
Internal regulator shutdown
Quiescent supply current with output off
V
IN
rising
V
IN
falling
CDI&CDO pin grounded
Description
Conditions
Min.
4.5
Typ.
-
3.6
3.65
3.55
170
1.8
5
Max.
30
Unit
V
V
V
V
uA
mA
Quiescent supply current with output CDI&CDO pin floating
switching
fsw= 250kHz
Mean current sense threshold voltage
(Defines LED current setting accuracy)
Sense threshold hysteresis
System current hysteresis
I
OUT
=0.5A½1.5A
V
SENSE
= V
IN
-0.1
I
SENSE
pin input current
CDO Output Voltage
CDO Output Voltage High
CDO Output Voltage Low
High Threshold Voltage
Low Threshold Voltage
Hysteresis Voltage
TTL OUTPUT
TTL OUTPUT
V
CDI
=0V-5V,
CDS＜2MΩ
V
CDI
=0V-5V,
CDS＜2MΩ
2
Measured on I
SENSE
pin with
respect to V
IN
,
95
I
SENSE
I
SENTH
I
SENSE
V
CDO
V
OH CDO
V
OL CDO
V
CDI VP
V
CDI
V
N
V
CDI
V
H
100
±15
105
mV
%
±25
10
50
5
5
0
2
0.8
1.2
0.8
%
uA
ppm/K
V
V
V
V
V
Δ
V
REF
/
Δ
T Temperature coefficient of VREF
TM Technology, Inc. reserves the right
to change products or specifications without notice.
P. 3
Publication Date: Sep . 2014
Revision:C
tm
T
CDI VTH
T
CDI VTN
V
DT
I
LXM
R
LX
I
LXI
T
TP
TE
CH
High Hold up time
Low Hold time
Slow start
Continuous LX switch current(
Note)
LX Switch ‘On’ resistance
LX switch leakage current
Thermal Shutdown Protect
Operating frequency
Minimum switch ‘ON’ time
Minimum switch ‘OFF’ time
V
CD
I
＞2V
V
CD
I
＜0.8V
Vref=1.25V
TA=25℃
Preliminary
T8309AD
1.5
30
300
1.5
0.3
0.35
5
160
CDI/CDO pin floating,
L=33uH(0.093ohm)
I
OUT
=1.5A @V
LED
=3.6V
Driving 1LED
LX switch ‘ON’
LX switch ‘OFF’
280
240
200
800
1
0.2
50
0.9
ns
S
uS
μS
A
Ω
uA
℃
KHz
ns
ns
ns
MHz
V
IN
12V @I
LX
=1.5A
SOP -8
f
LX
T
ONmin
T
OFFmin
T
PWminR
f
LXmax
D
LX
T
PD
Recommended minimum switch ‘ON’ time LX switch 'ON' or ‘OFF’
Recommended maximum operating
frequency
Recommended duty cycle range of output
switch at fLXmax
Internal comparator propagation delay
Notes :
**Parameters are not tested at production. Parameters are guaranteed by design, characterization and process
control.Block Diagram
**Operating temperature 25℃ and adequate cooling conditions, the temperature, the higher the maximum current
decreasing
Block Diagram
TM Technology, Inc. reserves the right
to change products or specifications without notice.
P. 4
Publication Date: Sep . 2014
Revision:C
tm
TE
CH
Preliminary
T8309AD
TM Technology, Inc. reserves the right
to change products or specifications without notice.
P. 5
Publication Date: Sep . 2014
Revision:C
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