Storage Temperature Range .................. –65°C to 150°C
PIN CONFIGURATION
TOP VIEW
TRACK/SS
TOP VIEW
I
LIM
V
IN
FREQ
TRACK/SS
FREQ
16 PGND
15 EXTV
CC
14 INTV
CC
13 BG
12 BOOST
11 SW
1
2
3
4
5
6
7
8
9
21
SGND
20 I
LIM
19 V
IN
18 PGND
17 EXTV
CC
16 INTV
CC
15 BG
14 BOOST
13 SW
12 TG
11 PGOOD
20 19 18 17
PLLIN/MODE 1
SGND 2
SGND 3
RUN 4
SENSE
–
PLLIN/MODE
SGND
SGND
RUN
SENSE
–
SENSE
+
21
SGND
5
SENSE
+
6
7
V
FB
8
ITH
9 10
PGOOD
TG
V
FB
ITH 10
UDC PACKAGE
20-LEAD (3mm
×
4mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 21) IS SGND, MUST BE SOLDERED TO PCB
FE PACKAGE
20-LEAD PLASTIC TSSOP
T
JMAX
= 150°C,
θ
JA
= 38°C/W
EXPOSED PAD (PIN 21) IS SGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3891EUDC#PBF
LTC3891IUDC#PBF
LTC3891HUDC#PBF
LTC3891MPUDC#PBF
TAPE AND REEL
LTC3891EUDC#TRPBF
LTC3891IUDC#TRPBF
LTC3891HUDC#TRPBF
LTC3891MPUDC#TRPBF
PART MARKING*
LFXV
LFXV
LFXV
LFXV
PACKAGE DESCRIPTION
20-Lead (3mm × 4mm) Plastic QFN
20-Lead (3mm × 4mm) Plastic QFN
20-Lead (3mm × 4mm) Plastic QFN
20-Lead (3mm × 4mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–55°C to 150°C
3891fa
2
LTC3891
ORDER INFORMATION
LEAD FREE FINISH
LTC3891EFE#PBF
LTC3891IFE#PBF
LTC3891HFE#PBF
LTC3891MPFE#PBF
TAPE AND REEL
LTC3891EFE#TRPBF
LTC3891IFE#TRPBF
LTC3891HFE#TRPBF
LTC3891MPFE#TRPBF
PART MARKING*
LTC3891FE
LTC3891FE
LTC3891FE
LTC3891FE
PACKAGE DESCRIPTION
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–55°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
V
IN
V
FB
PARAMETER
Input Supply Operating Voltage Range
Regulated Feedback Voltage
The
l
denotes the specifications which apply over the full operating junction
temperature range, otherwise specifications are at T
A
= 25°C (Note 2), V
IN
= 12V, V
RUN
= 5V, EXTV
CC
= 0V unless otherwise noted.
CONDITIONS
(Note 4); I
TH
Voltage = 1.2V
–40°C to 85°C
LTC3891E, LTC3891I
LTC3891H, LTC3891MP
(Note 4)
(Note 4); V
IN
= 4.5V to 60V
(Note 4)
Measured in Servo Loop;
∆I
TH
Voltage = 1.2V to 0.7V
(Note 4)
Measured in Servo Loop;
∆I
TH
Voltage = 1.2V to 2V
g
m
I
Q
Transconductance Amplifier g
m
Input DC Supply Current
Pulse Skip or Forced Continuous Mode
Sleep Mode
Shutdown
UVLO
V
OVL
I
SENSE+
I
SENSE–
DF
MAX
I
TRACK/SS
V
RUN
On
V
RUN
Hyst
V
SENSE(MAX)
Undervoltage Lockout
Feedback Overvoltage Protection
SENSE
+
Pin Current
SENSE
–
Pins Current
Maximum Duty Factor
Soft-Start Charge Current
RUN Pin On Threshold
RUN Pin Hysteresis
Maximum Current Sense Threshold
V
FB
= 0.7V, V
SENSE–
= 3.3V, I
LIM
= 0
V
FB
= 0.7V, V
SENSE–
= 3.3V, I
LIM
= INTV
CC
V
FB
= 0.7V, V
SENSE–
= 3.3V, I
LIM
= FLOAT
l
l
l
l
MIN
4
0.792
0.788
0.786
TYP
MAX
60
UNITS
V
V
V
V
nA
%/V
%
l
l
0.800
0.800
0.800
±5
0.002
0.01
0.808
0.812
0.812
±50
0.02
0.1
I
FB
V
REFLNREG
V
LOADREG
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
l
–0.01
–0.1
%
(Note 4); I
TH
= 1.2V; Sink/Source 5µA
(Note 5)
V
FB
= 0.83V (No Load)
V
FB
= 0.83V (No Load)
RUN = 0V
INTV
CC
Ramping Up
INTV
CC
Ramping Down
Measured at V
FB
Relative to Regulated V
FB
V
SENSE–
< INTV
CC
– 0.5V
V
SENSE–
> INTV
CC
+ 0.5V
In Dropout
V
TRACK
= 0V
V
RUN
Rising
l
l
l
2
2
50
14
3.6
7
3.92
3.80
10
75
25
4.2
4.0
13
±1
700
98
7
1.15
22
43
64
99
10
1.21
50
30
50
75
36
57
85
14
1.27
±2
mmho
mA
µA
µA
V
V
%
µA
µA
µA
%
µA
V
mV
mV
mV
mV
3891fa
3
LTC3891
ELECTRICAL CHARACTERISTICS
SYMBOL
Gate Driver
TG
BG
TG t
r
TG t
f
BG t
r
BG t
f
TG/BG t
1D
BG/TG t
1D
t
ON(MIN)
V
INTVCCVIN
V
LDOVIN
V
INTVCCEXT
V
LDOEXT
V
EXTVCC
V
LDOHYS
f
25kΩ
f
65kΩ
f
105kΩ
f
LOW
f
HIGH
f
SYNC
PGOOD1 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
Hysteresis
V
FB
Ramping Positive
Hysteresis
t
PG
Delay for Reporting a Fault
7
–13
–10
2.5
10
2.5
25
13
–7
%
%
%
%
µs
3891fa
The
l
denotes the specifications which apply over the full operating junction
temperature range, otherwise specifications are at T
A
= 25°C (Note 2), V
IN
= 12V, V
RUN
= 5V, EXTV
CC
= 0V unless otherwise noted.
PARAMETER
Pull-Up On-Resistance
Pull-Down On-Resistance
Pull-Up On-Resistance
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
Internal V
CC
Voltage
INTV
CC
Load Regulation
EXTV
CC
Switchover Voltage
EXTV
CC
Hysteresis
Programmable Frequency
Programmable Frequency
Programmable Frequency
Low Fixed Frequency
High Fixed Frequency
Synchronizable Frequency
R
FREQ
= 25k;
PLLIN/MODE = DC Voltage
R
FREQ
= 65k;
PLLIN/MODE = DC Voltage
R
FREQ
=105k;
PLLIN/MODE = DC Voltage
V
FREQ
= 0V;
PLLIN/MODE = DC Voltage
V
FREQ
= INTV
CC
;
PLLIN/MODE = DC Voltage
PLLIN/MODE = External Clock
l
CONDITIONS
MIN
TYP
2.5
1.5
2.4
1.1
MAX
UNITS
Ω
Ω
Ω
Ω
ns
ns
ns
ns
ns
ns
ns
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
C
LOAD
= 3300pF
C
LOAD
= 3300pF
(Note 7)
6V < V
IN
< 60V, V
EXTVCC
= 0V
I
CC
= 0mA to 50mA, V
EXTVCC
= 0V
6V < V
EXTVCC
< 13V
I
CC
= 0mA to 50mA,
V
EXTVCC
= 8.5V
I
CC
= 0mA to 50mA,
EXTV
CC
Ramping Positive
4.5
4.85
4.85
25
16
25
13
30
30
95
5.1
0.7
5.1
0.6
4.7
250
105
375
440
835
320
485
75
0.2
350
535
380
585
750
0.4
±1
505
5.35
1.1
5.35
1.1
4.9
INTV
CC
Linear Regulator
V
%
V
%
V
mV
kHz
kHz
kHz
kHz
kHz
kHz
V
µA
Oscillator and Phase-Locked Loop
4
LTC3891
ELECTRICAL CHARACTERISTICS
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 LTC3891 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3891E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3891I is guaranteed
over the –40°C to 125°C operating junction temperature range, the
LTC3891H is guaranteed over the –40°C to 150°C operating junction
temperature range and the LTC3891MP is tested and guaranteed over
the –55°C to 150°C operating junction temperature range. High junction
temperatures degrade operating lifetimes; operating lifetime is derated
for junction temperatures greater than 125°C. Note that the maximum
ambient temperature consistent with these specifications is determined by
specific operating conditions in conjunction with board layout, the rated
package thermal impedance and other environmental factors.
Note 3:
The junction temperature (T
J
, in °C) is calculated from the ambient
temperature (T
A
, in °C) and power dissipation (P
D
, in Watts) according to
the formula:
T
J
= T
A
+ (P
D
•
θ
JA
), where
θ
JA
is 43°C/W for the QFN or 38°C/W for the
TSSOP
.
Note 4:
The LTC3891 is tested in a feedback loop that servos V
ITH
to a
specified voltage and measures the resultant V
FB
. The specification at
85°C is not tested in production and is assured by design, characterization
and correlation to production testing at other temperatures (125°C for
the LTC3891E/LTC3891I, 150°C for the LTC3891H/LTC3891MP). For the
LTC3891MP the specification at –40°C is not tested in production and is
,
assured by design, characterization and correlation to production testing
at –55°C.
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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