Datasheet

LT3746
4
3746fa
For more information www.linear.com/3746
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Gate Driver
V
BIAS
CAP Bias Voltage (V
IN
– V
CAP
) 7V < V
IN
< 55V 6.54 6.77 7.00 V
I
CAP
CAP Bias Current Limit (V
IN
– V
CAP
) = V
BIAS
– 0.5V 22 mA
GATE High Level (V
IN
– V
GATE
) I
GATE
= –100mA 0.4 V
GATE Low Level (V
GATE
– V
CAP
) I
GATE
= 100mA 0.3 V
GATE Rise Time C
GATE
= 3.3nF to V
IN
, V
IN
= 12V 30 ns
GATE Fall Time C
GATE
= 3.3nF to V
IN
, V
IN
= 12V 30 ns
LED Driver
V
ISET
Trimmed I
SET
Pin Voltage
l
1.181 1.205 1.229 V
LEDxx Operating Voltage V
ISP
= V
ISN
= V
LEDxx
l
0 13 V
LEDxx Leakage Current LED Channel Off, V
ISP
= V
ISN
= 5V,
V
LEDxx
= 3V
0.2 µA
I
LED
LED Constant Sink Current V
ISP
= V
ISN
= 5V, V
LEDxx
= 0.5V
REG
DC
= 0x00
REG
DC
= 0x20
REG
DC
= 0x3F
7
15.5
23
11.5
21.5
30
16
27.5
37
mA
mA
mA
∆I
LEDC
Current Mismatch Between Channels V
ISP
= V
ISN
= 5V, V
LEDxx
= 0.5V,
REG
DC
= 0x20 (Note 6)
8 20 %
∆I
LEDD
Current Mismatch Between Devices V
ISP
= V
ISN
= 5V, V
LEDxx
= 0.5V,
REG
DC
= 0x20 (Note 7)
–15 5 20 %
∆I
LINE
LED Current Line Regulation V
ISP
= V
ISN
= 5V, V
LEDxx
= 0.5V,
REG
DC
= 0x20, V
CC
= 3V to 5.5V (Note 8)
–0.2 0.2 1 %/V
∆I
LOAD
LED Current Load Regulation V
ISP
= V
ISN
= 5V, REG
DC
= 0x20,
V
LEDxx
= 0.5V to 2.5V (Note 9)
–1 1 3 %/V
V
OPEN
Open LED Threshold V
ISP
= V
ISN
= 5V, V
LEDxx
Falling 0.1 V
V
SHT
Short LED Threshold V
ISP
= V
ISN
= 5V, V
LEDxx
Rising 3.65 3.9 4.15 V
T
LEDON
Minimum LED On Time V
ISP
= V
ISN
= 5V, REG
GS
= 0x001 0.5 µs
PWMCK LOGIC
High Level Voltage
Low Level Voltage
V
CC
= 3V to 5.5V
2.4
0
V
CC
0.6
V
V
Th
ermal Protection
I
TSET
T
SET
Output Current V
TSET
= 1V
l
19.0 19.8 20.6 µA
T
SET
Over Temperature Threshold T
A
= 25°C 510 mV
Serial Data Interface
V
SIH
V
SIL
Single-Ended Input (Note 10)
High Level Voltage
Low Level Voltage
V
CC
= 3V to 5.5V
2.4
0
V
CC
0.6
V
V
I
SI
Single-Ended Input Current V
CC
= 3V to 5.5V, SI = V
CC
or GND –0.2 0.2 µA
V
SOH
V
SOL
Single-Ended Output (Note 10)
High Level Voltage
Low Level Voltage
V
CC
= 3V to 5.5V
I
SO
= –1mA
I
SO
= 1mA
V
CC
– 0.1
0.1
V
V
V
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 24V, V
CC
= 3.3V, V
EN/UVLO
= 1.5V, V
FB
= 1.5V,
V
ISP
= V
ISN
= 0V, R
T
= 105k, R
ISET
= 60.4k, C
CAP
= 0.47µF to V
IN
, unless otherwise noted.