...............................................................–0.3V to 6V
SCKI, SCKO, SDI, SDO, LDI, LDO, PWMCK, SYNC,
SS, EN/UVLO ............................................. –0.3V to V
CC
Operating Junction Temperature Range
(Notes 2, 3)............................................–40°C to 125°C
Storage Temperature Range ..................–65°C to 125°C
56 55 54 53 52 51 50 49 48 47
EN/UVLO 1
LED15 2
LED14 3
LED13 4
LED12 5
LED11 6
LED10 7
LED09 8
LED08 9
LED07 10
LED06 11
LED05 12
LED04 13
LED03 14
LED02 15
LED01 16
LED00 17
GND 18
UHH PACKAGE
56-LEAD (5mm
×
9mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 32°C/W,
θ
JC
= 2.0°C/W
EXPOSED PAD (PIN 57) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LT3746EUHH#PBF
LT3746IUHH#PBF
TAPE AND REEL
LT3746EUHH#TRPBF
LT3746IUHH#TRPBF
PART MARKING*
3746
3746
PACKAGE DESCRIPTION
56-Lead (5mm
×
9mm) Plastic QFN
56-Lead (5mm
×
9mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
2
3746fa
For more information
www.linear.com/3746
LT3746
elecTrical characTerisTics
SYMBOL
Supply
V
IN
I
VIN
V
CC
I
VCC
V
IN
Operating Voltage
V
IN
Supply Current
V
CC
Operating Voltage
V
CC
Supply Current (Note 4)
V
EN/UVLO
= 0V
LED Channel Off, 30MHz Data Off
LED Channel On, 30MHz Data Off
LED Channel On, 30MHz Data On
V
CC
Rising
V
CC
Falling
I
VCC
<20µA
V
EN/UVLO
Rising
V
EN/UVLO
Falling
V
EN/UVLO
= V
CC
(V
IN
– V
CAP
) Rising
(V
IN
– V
CAP
) Falling
V
SS
= 1V
V
SS
= V
CC
, V
EN/UVLO
= 1V
4.6
4.1
–16
2.82
2.61
0.35
1.28
1.19
V
EN/UVLO
= 0V
No Switching
l
l
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.
PARAMETER
CONDITIONS
MIN
6
0.2
0.4
3
0.1
3.3
10
19
2.89
2.68
1.31
1.22
0.1
4.9
4.4
–12
330
0.35
1.186
V
RT
= 0V
R
T
= 280k, V
IN
= 12V
R
T
= 105k, V
IN
= 12V
R
T
= 46.4k, V
IN
= 12V
R
T
= 348k, V
IN
= 12V
V
IN
= 12V, V
CC
= 3V to 5.5V
185
470
950
200
2.4
0
l
TYP
MAX
55
2
0.55
5.5
1
4.0
UNITS
V
µA
mA
V
µA
mA
mA
mA
V
V
V
V
V
µA
V
V
µA
µA
V
Undervoltage Lockout (UVLO)
V
CC
UVLO Threshold
EN/UVLO Shutdown Threshold
UVLO Threshold
I
EN/UVLO
EN/UVLO Bias Current
(V
IN
– V
CAP
) UVLO Threshold
Soft Start (SS)
I
SS
V
SS(TH)
Oscillator
V
RT
I
RT
f
OSC
f
SYNC
RT Pin Voltage
RT Pin Current Limit
Oscillator Frequency
1.205
–80
205
510
1050
225
550
1150
1000
V
CC
0.6
1.210
–120
0.44
0.54
120
200
0.64
1.234
1.224
V
µA
kHz
kHz
kHz
kHz
V
V
V
nA
V
ns
ns
Soft Start Charge Current
Soft Start Discharge Current
Soft Start Reset Threshold
–8
2.96
2.75
1.34
1.25
1
5.2
4.7
Sync Frequency Range (Note 5)
SYNC LOGIC
High Level Voltage
Low Level Voltage
Error Amplifiers and Loop Dynamics
V
FB
I
FB
T
OFF(MIN)
T
ON(MIN)
FB Regulation Voltage
FB Input Bias Current
LED Regulation Voltage
Minimum GATE Off Time
Minimum GATE On Time
V
ISP
= V
ISN
= 5V
V
ISP
= V
ISN
= 5V, V
FB
Regulated
V
ISP
= V
ISN
= 5V, V
FB
= 1V
V
IN
= 12V, V
ISP
= V
ISN
= 5V, V
FB
= 1V
V
IN
= 12V, (V
ISP
– V
ISN
) = 60mV, V
ISN
= 5V,
V
FB
= 1V
V
ISP
= V
ISN
V
IN
= 12V, V
ISP
= V
ISN
, V
FB
= 1V
l
l
1.186
Current Sense Amplifier
ISP/ISN Pin Common Mode
V
IN
to ISN Dropout Voltage (V
IN
– V
ISN
)
I
ISP
I
ISN
ISP Input Bias Current
ISN Input Bias Current
0
1.7
34
46.5
–23
–48
13
2
59
V
V
mV
µA
µA
3746fa
Current Limit Sense Threshold (V
ISP
– V
ISN
) V
FB
= 1V
For more information
www.linear.com/3746
3
LT3746
elecTrical characTerisTics
SYMBOL
Gate Driver
V
BIAS
I
CAP
CAP Bias Voltage (V
IN
– V
CAP
)
CAP Bias Current Limit
GATE High Level (V
IN
– V
GATE
)
GATE Low Level (V
GATE
– V
CAP
)
GATE Rise Time
GATE Fall Time
LED Driver
V
ISET
Trimmed I
SET
Pin Voltage
LEDxx Operating Voltage
LEDxx Leakage Current
I
LED
LED Constant Sink Current
V
ISP
= V
ISN
= V
LEDxx
LED Channel Off, V
ISP
= V
ISN
= 5V,
V
LEDxx
= 3V
V
ISP
= V
ISN
= 5V, V
LEDxx
= 0.5V
REG
DC
= 0x00
REG
DC
= 0x20
REG
DC
= 0x3F
V
ISP
= V
ISN
= 5V, V
LEDxx
= 0.5V,
REG
DC
= 0x20 (Note 6)
V
ISP
= V
ISN
= 5V, V
LEDxx
= 0.5V,
REG
DC
= 0x20 (Note 7)
V
ISP
= V
ISN
= 5V, V
LEDxx
= 0.5V,
REG
DC
= 0x20, V
CC
= 3V to 5.5V (Note 8)
V
ISP
= V
ISN
= 5V, REG
DC
= 0x20,
V
LEDxx
= 0.5V to 2.5V (Note 9)
V
ISP
= V
ISN
= 5V, V
LEDxx
Falling
V
ISP
= V
ISN
= 5V, V
LEDxx
Rising
V
ISP
= V
ISN
= 5V, REG
GS
= 0x001
V
CC
= 3V to 5.5V
2.4
0
l
l
l
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.
PARAMETER
CONDITIONS
7V < V
IN
< 55V
(V
IN
– V
CAP
) = V
BIAS
– 0.5V
I
GATE
= –100mA
I
GATE
= 100mA
C
GATE
= 3.3nF to V
IN
, V
IN
= 12V
C
GATE
= 3.3nF to V
IN
, V
IN
= 12V
1.181
0
MIN
6.54
TYP
6.77
22
0.4
0.3
30
30
1.205
1.229
13
0.2
MAX
7.00
UNITS
V
mA
V
V
ns
ns
V
V
µA
7
15.5
23
11.5
21.5
30
8
16
27.5
37
20
20
1
3
mA
mA
mA
%
%
%/V
%/V
V
∆I
LEDC
∆I
LEDD
∆I
LINE
∆I
LOAD
V
OPEN
V
SHT
T
LEDON
Current Mismatch Between Channels
Current Mismatch Between Devices
LED Current Line Regulation
LED Current Load Regulation
Open LED Threshold
Short LED Threshold
Minimum LED On Time
PWMCK LOGIC
High Level Voltage
Low Level Voltage
–15
–0.2
–1
5
0.2
1
0.1
3.65
3.9
0.5
4.15
V
µs
V
CC
0.6
19.8
510
20.6
V
V
µA
mV
Thermal Protection
I
TSET
T
SET
Output Current
T
SET
Over Temperature Threshold
Serial Data Interface
V
SIH
V
SIL
I
SI
V
SOH
V
SOL
Single-Ended Input (Note 10)
High Level Voltage
Low Level Voltage
Single-Ended Input Current
Single-Ended Output (Note 10)
High Level Voltage
Low Level Voltage
V
CC
= 3V to 5.5V
V
CC
= 3V to 5.5V, SI = V
CC
or GND
V
CC
= 3V to 5.5V
I
SO
= –1mA
I
SO
= 1mA
2.4
0
–0.2
V
CC
– 0.1
V
CC
0.6
0.2
V
V
µA
V
V
V
V
TSET
= 1V
T
A
= 25°C
19.0
0.1
4
3746fa
For more information
www.linear.com/3746
LT3746
TiMing characTerisTics
SYMBOL
f
SCKI
f
PWMCK
t
WH-CKI
t
WL-CKI
t
WH-PWM
t
WL-PWM
t
WH-LDI
t
SU-SDI
t
HD-SDI
t
SU-LDI
t
HD-LDI
t
PD-SCK↑
t
PD-SCK↓
∆t
PD-SCK
t
PD-SD
t
PD-LD↑
t
PD-LD↓
∆t
PD-LD
t
PD-PWM
t
R-SO
t
F-SO
PARAMETER
Data Shift Clock Frequency
PWMCK Clock Frequency
SCKI Pulse Duration
PWMCK Pulse Duration
LDI Pulse Duration
SDI-SCKI Setup Time
SCKI-SDI Hold Time
SCKI-LDI Setup Time
LDI-SCKI Hold Time
SCKI = H (Figure 3)
SCKI = L (Figure 3)
PWMCK = H (Figure 4)
PWMCK = L (Figure 4)
LDI = H (Figure 3)
SDI – SCKI
↑
(Figure 3)
SCKI
↑
– SDI (Figure 3)
SCKI
↓
– LDI
↑
(Figure 3)
LDI
↓
– SCKI
↑
(Figure 3)
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
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