CPOR, RT, ILIM Voltage ..............................................3V
SR, TXEN1, TXD1, TXEN2, TXD2 Voltage .................30V
SC1, SC2, WAKE, RST,
RXD1 Voltage .......................30V
Operating Junction Temperature
Range (Notes 4 and 5)
LT3669E ............................................ –40°C to 125°C
LT3669I ............................................. –40°C to 125°C
LT3669H ............................................ –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
PIN CONFIGURATION
LT3669
TOP VIEW
AGND
CPOR
SYNC
ILIM
RST
LT3669-2
TOP VIEW
AGND
22 RT
21 FB
OUT
29
GND
20 FB
LDO
19 LDO
18 LDO
IN
17 BD
16 BST
15 SW
9 10 11 12 13 14
Q2
CQ1
L+
EN/UVLO
DIO
DA
CPOR
SYNC
ILIM
RST
SR
SR
28 27 26 25 24 23
SC1
1
SC2
2
WAKE
3
RXD1 4
TXEN1 5
TXD1 6
TXEN2 7
TXD2 8
9 10 11 12 13 14
Q2
CQ1
L+
EN/UVLO
DIO
GND
29
GND
22 RT
21 FB
OUT
20 FB
LDO
19 LDO
18 LDO
IN
17 BD
16 BST
15 SW
SC1
1
SC2
2
WAKE
3
RXD1 4
TXEN1 5
TXD1 6
TXEN2 7
TXD2 8
28 27 26 25 24 23
UFD PACKAGE
28-LEAD (4mm
×
5mm) PLASTIC QFN
θ
JA
= 44°C/W,
θ
JC
= 8°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
UFD PACKAGE
28-LEAD (4mm
×
5mm) PLASTIC QFN
θ
JA
= 44°C/W,
θ
JC
= 8°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
3669fa
2
For more information
www.linear.com/LT3669
LT3669/LT3669-2
ORDER INFORMATION
LEAD FREE FINISH
LT3669EUFD#PBF
LT3669IUFD#PBF
LT3669HUFD#PBF
LT3669EUFD-2#PBF
LT3669IUFD-2#PBF
LT3669HUFD-2#PBF
TAPE AND REEL
LT3669EUFD#TRPBF
LT3669IUFD#TRPBF
LT3669HUFD#TRPBF
LT3669EUFD-2#TRPBF
LT3669IUFD-2#TRPBF
LT3669HUFD-2#TRPBF
PART MARKING*
3669
3669
3669
36692
36692
36692
PACKAGE DESCRIPTION
28-Lead (4mm × 5mm) Plastic QFN
28-Lead (4mm × 5mm) Plastic QFN
28-Lead (4mm × 5mm) Plastic QFN
28-Lead (4mm × 5mm) Plastic QFN
28-Lead (4mm × 5mm) Plastic QFN
28-Lead (4mm × 5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–40°C to 125°C
–40°C to 125°C
–40°C to 150°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/
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
Power Supply
L+ Undervoltage Lockout Threshold
V
OVTH
L+ Overvoltage Lockout Threshold
Shutdown Current from L+
Quiescent Current from L+
Switching Regulator
V
FBOUT
Switching Regulator Feedback Voltage
FB
OUT
Pin Bias Current
FB
OUT
Voltage Line Regulation
Switching Frequency
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
L+
= 24V. (Note 4)
CONDITIONS
V
L+
Rising
V
L+
Rising
V
EN/UVLO
= 0.4V
Not Switching
l
l
l
MIN
TYP
6.4
MAX
7.5
45
1.65
6
811
–100
2.62
1.20
297
210
410
820
UNITS
V
V
mA
mA
mV
nA
%/V
MHz
MHz
kHz
ns
kHz
mA
mA
mV
mV
40.5
43
1.15
4
777
794
–15
0.005
FB
OUT
Pin Voltage = 800mV
7.5V < V
L+
< 40V
R
T
= 5.36k
R
T
= 19.1k
R
T
= 107k
R
T
= 19.1k
R
T
= 19.1k, FB
OUT
= 0V
LT3669
LT3669-2
I
SW
= –100mA (LT3669)
I
SW
= –300mA (LT3669-2)
I
SW
= –100mA (LT3669)
LT3669
LT3669-2
I
DIO
= –100mA (LT3669)
I
DIO
= –300mA (LT3669-2)
V
L+
= 0V, V
DI0
= 24V
I
BST
= –6mA (LT3669)
I
BST
= –15mA (LT3669-2)
V
BST
– V
BD
= 24V
l
1.94
0.88
219
l
2.28
1.04
258
130
115
Minimum Switch Off-Time
Foldback Frequency
Switch Current Limit (Note 6)
Switch V
CESAT
(V
DIO
– V
SW
)
Switch Leakage Current
Catch Schottky Diode Forward Voltage Drop
Catch Schottky Diode Current Limit to Stop
Internal Oscillator
Reverse Protection Diode Forward
Voltage Drop
Reverse Protection Diode Reverse Leakage
Boost Schottky Diode Forward Voltage Drop
Boost Schottky Diode Reverse Leakage
Minimum BST Voltage (Note 7)
l
l
240
480
325
650
330
550
0.01
720
2
260
570
µA
mV
mA
mA
mV
mV
140
330
200
450
720
840
0.01
700
750
0.01
1.4
2
µA
mV
mV
2
1.8
µA
V
3669fa
For more information
www.linear.com/LT3669
3
LT3669/LT3669-2
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
BST Pin Current
SYNC Threshold Voltage
SYNC Input Frequency
EN/UVLO Threshold Voltage
EN/UVLO Pin Hysteresis
LDO Linear Regulator
V
FBLDO
LDO Feedback Voltage
FB
LDO
Pin Bias Current
FB
LDO
Voltage Line Regulation
LDO Current Limit
LDO Current Limit Foldback
LDO Dropout Voltage
LDO Minimum Load Current
Power-On Reset
V
RSTTH
t
RST
t
UV
Reset Threshold as % of V
FBOUT
(V
FBLDO
)
Reset Timeout Period
UV Detect to
RST
Asserted
FB
OUT
(FB
LDO
) Pin Voltage Falling (Figure 6)
C
POR
= 100nF,
RST
R
PU
= 100k (Figure 6)
Step V
FBOUT
(V
FBLDO
) from 0.9V to 0.5V,
RST
R
PU
= 100k (Figure 6)
Junction Temperature T
J
Increasing
Junction Temperature T
J
Decreasing
l
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
L+
= 24V. (Note 4)
CONDITIONS
I
SW
= –100mA (LT3669)
I
SW
= –300mA (LT3669-2)
0.5
0.3
V
EN/UVLO
Rising
l
l
MIN
TYP
5.25
10.5
0.9
1.5
75
794
–20
0.005
MAX
7.5
15
1.5
2.2
1.56
100
811
–100
235
55
90
175
95
15
37
UNITS
mA
mA
V
MHz
V
mV
mV
nA
%/V
mA
mA
mV
mV
µA
%
ms
µs
1.44
50
777
FB
LDO
Pin Voltage = 800mV
7.5V < V
L+
< 40V, V
L+
– V
LDO
> 4V
l
l
151
15
180
35
60
340
150
V
LDOIN
= 40V, V
LDO
= 0V
LDO Load Current = 25mA
LDO Load Current = 150mA
l
l
l
90.4
10
11
92.7
12.5
24
Line Driver Thermal Shutdown
Thermal Shutdown Threshold (Note 8)
Thermal Shutdown Threshold (Note 8)
Thermal Shutdown Hysteresis (Note 8)
Line Drivers
I
QH
I
QL
V
RQH
V
RQL
DC Driver Current
P-Switching Output (ON State)
DC Driver Current
N-Switching Output (ON State)
Residual Voltage High (V
L+
to V
CQ1,Q2
)
Residual Voltage Low (V
CQ1,Q2
)
V
RQH
(V
RQL
) Pulsing Threshold
V
RQH
(V
RQL
) Pulsing Threshold Hysteresis
CQ1, Q2 Pin Leakage Current
Receiver
V
THH
V
THL
V
HYS
Input Threshold “H”
Input Threshold “L”
Input Hysteresis
V
L+
> 18V (Figure 14)
V
L+
> 18V (Figure 14)
V
L+
> 18V (Figure 14)
l
l
l
125
111
10
140
128
12
140
330
140
330
1.15
1.5
1.15
1.5
155
135
14
190
420
190
420
1.65
2.1
1.65
2.1
3.2
80
±3
±8
13
11.2
2.6
°C
°C
°C
mA
mA
mA
mA
V
V
V
V
V
mV
µA
µA
V
V
V
V
ILIM
≤ 0.3V, 7.5V < V
L+
< 40V
R
ILIM
= 42.2k, 7.5V < V
L+
< 40V
V
ILIM
≤ 0.3V, 7.5V < V
L+
< 40V
R
ILIM
= 42.2k, 7.5V < V
L+
< 40V
I
CQ1,Q2
= –100mA
I
CQ1,Q2
= –250mA
I
CQ1,Q2
= 100mA
I
CQ1,Q2
= 250mA
V
RQH
(V
RQL
) Increasing
–40°C to 125°C, V
TXENn
< 0.4V
–40°C to 150°C, V
TXENn
< 0.4V
l
l
l
l
l
l
l
l
105
280
105
280
2.7
20
l
l
2.95
50
±1.2
±1.2
10.5
8.0
1.8
11.8
9.6
2.2
3669fa
4
For more information
www.linear.com/LT3669
LT3669/LT3669-2
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
Digital IO
WAKE,
RXD1,
SCn
Pull-Down Output Current
if Asserted
RST
Pull-Down Output Current if Asserted
V
IH
V
IL
I
LK
C
IN
TXDn, TXENn, SR Input High Voltage
TXDn, TXENn, SR Input Low Voltage
TXDn, TXENn, SR Pin Input Leakage Current
TXDn, TXENn, SR Pin Input Capacitance
V
SCn
= V
WAKE
= V
RXD1
= 0.3V
V
RST
= 0.3V
l
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
L+
= 24V. (Note 4)
CONDITIONS
MIN
0.7
0.2
0.9
0.4
0.1
2.5
1
TYP
1.05
0.3
MAX
UNITS
mA
mA
V
V
µA
pF
SWITCHING CHARACTERISTICS
SYMBOL
f
DTR
t
BIT
Driver
t
DR
t
DF
t
PHLD
, t
PLHD
t
SKEWD
t
ZHD
, t
ZLD
t
HZD
, t
LZD
t
DWU
t
LZW
Rise Time
PARAMETER
Maximum Data Transfer Rate
Driver and Receiver
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
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