EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
TOP VIEW
FREQ/PLLFLTR
MODE/PLLIN
SENSE1
+
RUN1
SW1
28 27 26 25 24 23
SENSE1
–
1
TK/SS1 2
ITH1 3
VFB1 4
VFB2 5
ITH2 6
TK/SS2 7
SENSE2
–
8
9 10 11 12 13 14
RUN2
ILIM
PGOOD
SENSE2
+
EXTV
CC
SW2
29
22 BOOST1
21 BG1
20 VIN
19 INTV
CC
18 BG2
17 PGND
16 BOOST2
15 TG2
UFD PACKAGE
28-LEAD (4mm × 5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 34°C/W, EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
TG1
TG1
2
Rev. D
For more information
www.analog.com
LTC3850/LTC3850-1
ORDER INFORMATION
LEAD FREE FINISH
LTC3850EGN#PBF
LTC3850EGN-1#PBF
LTC3850IGN#PBF
LTC3850IGN-1#PBF
LTC3850EUF#PBF
LTC3850EUFD#PBF
LTC3850IUF#PBF
LTC3850IUFD#PBF
AUTOMOTIVE PRODUCTS**
LTC3850EGN#WPBF
LTC3850EGN-1#WPBF
LTC3850IGN#WPBF
LTC3850IGN-1#WPBF
LTC3850EGN#WTRPBF
LTC3850EGN-1#WTRPBF
LTC3850IGN#WTRPBF
LTC3850IGN-1#WTRPBF
LTC3850GN
LTC3850GN-1
LTC3850GN
LTC3850GN-1
28-Lead Narrow Plastic SSOP
28-Lead Narrow Plastic SSOP
28-Lead Narrow Plastic SSOP
28-Lead Narrow Plastic SSOP
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
TAPE AND REEL
LTC3850EGN#TRPBF
LTC3850EGN-1#TRPBF
LTC3850IGN#TRPBF
LTC3850IGN-1#TRPBF
LTC3850EUF#TRPBF
LTC3850EUFD#TRPBF
LTC3850IUF#TRPBF
LTC3850IUFD#TRPBF
PART MARKING*
LTC3850GN
LTC3850GN-1
LTC3850GN
LTC3850GN-1
3850
3850
3850
3850
PACKAGE DESCRIPTION
28-Lead Narrow Plastic SSOP
28-Lead Narrow Plastic SSOP
28-Lead Narrow Plastic SSOP
28-Lead Narrow Plastic SSOP
28-Lead (4mm × 4mm) Plastic QFN
28-Lead (4mm × 5mm) Plastic QFN
28-Lead (4mm × 4mm) Plastic QFN
28-Lead (4mm × 5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
**Versions
of this part are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. These
models are designated with a #W suffix. Only the automotive grade products shown are available for use in automotive applications. Contact your
local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for
these models.
Rev. D
For more information
www.analog.com
3
LTC3850/LTC3850-1
ELECTRICAL CHARACTERISTICS
SYMBOL
V
FB1,2
I
FB1,2
V
REFLNREG
V
LOADREG
g
m1,2
I
Q
UVLO
UVLO
HYS
DF
MAX
V
OVL
I
SENSE
I
TK/SS1,2
V
RUN1,2
V
RUN1,2HYS
V
SENSE(MAX)
TG R
UP
TG R
DOWN
BG R
UP
BG R
DOWN
TG1,2 t
r
TG1,2 t
f
BG1,2 t
r
BG1,2 t
f
TG/BG t
1D
BG/TG t
2D
t
ON(MIN)
V
INTVCC
V
LDO
INT
V
EXTVCC
V
LDO
EXT
V
LDOHYS
PARAMETER
Regulated Feedback Voltage
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
Main Control Loops
I
TH1,2
Voltage = 1.2V; (Note 4)
(Note 4)
V
IN
= 6V to 24V (Note 4)
(Note 4)
Measured in Servo Loop; ∆I
TH
Voltage = 1.2V to 0.7V
Measured in Servo Loop; ∆I
TH
Voltage = 1.2V to 1.6V
I
TH1,2
= 1.2V; Sink/Source 5µA; (Note 4)
(Note 5)
V
IN
= 15V; EXTV
CC
Tied to V
OUT1
; V
OUT1
= 5V
V
RUN1,2
= 0V
V
INTVCC
Ramping Down
In Dropout
Measured at V
FB1,2
(Each Channel) V
SENSE1,2
= 3.3V
V
TK/SS1,2
= 0V
V
RUN1
, V
RUN2
Rising
V
FB1,2
= 0.7V, V
SENSE1,2
= 3.3V, I
LIM
= 0V
V
FB1,2
= 0.7V, V
SENSE1,2
= 3.3V, I
LIM
= Float
V
FB1,2
= 0.7V, V
SENSE1,2
= 3.3V, I
LIM
= INTV
CC
TG High
TG Low
BG High
BG Low
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
C
LOAD
= 3300pF Each Driver
C
LOAD
= 3300pF Each Driver
(Note 7)
7V < V
IN
< 24V
I
CC
= 0mA to 50mA
EXTV
CC
Ramping Positive
I
CC
= 20mA, V
EXTVCC
= 5V
l
l
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
IN
= 15V, V
RUN1,2
= 5V, unless otherwise noted.
CONDITIONS
MIN
0.792
TYP
0.800
–10
0.002
0.01
–0.01
2.2
850
30
3
0.5
96
0.84
0.9
1.1
20
40
60
97.2
0.86
±1
1.3
1.22
80
l
l
l
MAX
0.808
–50
0.02
0.1
–0.1
UNITS
V
nA
%/V
%
%
mmho
µA
µA
V
V
%
Transconductance Amplifier g
m
Input DC Supply Current
Normal Mode
Shutdown
Undervoltage Lockout on INTV
CC
UVLO Hysteresis
Maximum Duty Factor
Feedback Overvoltage Lockout
Sense Pin Bias Current
Soft-Start Charge Current
RUN Pin ON Threshold
RUN Pin ON Hysteresis
Maximum Current Sense Threshold
(Note 8)
TG Driver Pull-Up On-Resistance
TG Driver Pull-down On-Resistance
BG Driver Pull-Up On-Resistance
BG Driver Pull-down On-Resistance
TG Transition Time:
Rise Time
Fall Time
BG Transition Time:
Rise Time
Fall Time
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
Minimum On-Time
Internal V
CC
Voltage
INTV
CC
Load Regulation
EXTV
CC
Switchover Voltage
EXTV
CC
Voltage Drop
EXTV
CC
Hysteresis
50
0.88
±2
1.7
1.35
40
60
90
V
µA
µA
V
mV
mV
mV
mV
Ω
Ω
Ω
Ω
ns
ns
ns
ns
ns
ns
ns
30
50
75
2.6
1.5
2.4
1.1
25
25
25
25
30
30
90
INTV
CC
Linear Regulator
4.8
4.5
5
0.5
4.7
50
200
100
5.2
2
V
%
V
mV
mV
Rev. D
4
For more information
www.analog.com
LTC3850/LTC3850-1
ELECTRICAL CHARACTERISTICS
SYMBOL
f
NOM
f
LOW
f
HIGH
R
MODE/PLLIN
I
FREQ
PGOOD Output
V
PGL
I
PGOOD
V
PG
PGOOD Voltage Low
PGOOD Leakage Current
PGOOD Trip Level
I
PGOOD
= 2mA
V
PGOOD
= 5V
V
FB
with Respect to Set Regulated Voltage
V
FB
Ramping Negative
V
FB
Ramping Positive
–5
5
– 7.5
7.5
0.1
0.3
±2
–10
10
V
µA
%
%
PARAMETER
Nominal Frequency
Lowest Frequency
Highest Frequency
MODE/PLLIN Input Resistance
Phase Detector Output Current
Sinking Capability
Sourcing Capability
f
MODE
< f
OSC
f
MODE
> f
OSC
Oscillator and Phase-Locked Loop
V
FREQ
= 1.2V
V
FREQ
= 0V
V
FREQ
≥ 2.4V
450
210
700
500
250
780
250
–13
13
550
290
860
kHz
kHz
kHz
kΩ
µA
µA
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
IN
= 15V, V
RUN1,2
= 5V, unless otherwise noted.
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LTC3850E/LTC3850E-1 are guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3850I/LTC3850I-1
are guaranteed to meet performance specifications over the –40°C to 85°C
operating temperature range.
Note 3:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC3850GN: T
J
= T
A
+ (P
D
• 95°C/W)
LTC3850UF: T
J
= T
A
+ (P
D
• 37°C/W)
LTC3850UFD: T
J
= T
A
+ (P
D
• 43°C/W)
Note 4:
The LTC3850 is tested in a feedback loop that servos V
ITH1,2
to a
specified voltage and measures the resultant V
FB1,2
.
Note 5:
Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 6:
Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 7:
The minimum on-time condition is specified for an inductor
peak-to-peak ripple current ≥40% of I
MAX
(see Minimum On-Time
Considerations in the Applications Information section).
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