EXPOSED PAD (PIN 29) IS SGND, MUST BE SOLDERED TO PCB
GN PACKAGE
28-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 90°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC3858EUFD-1#PBF
LTC3858IUFD-1#PBF
LTC3858EGN-1#PBF
LTC3858IGN-1#PBF
TAPE AND REEL
LTC3858EUFD-1#TRPBF
LTC3858IUFD-1#TRPBF
LTC3858EGN-1#TRPBF
LTC3858IGN-1#TRPBF
PART MARKING*
38581
38581
LTC3858GN-1
LTC3858GN-1
PACKAGE DESCRIPTION
28-Lead (4mm
×
5mm) Plastic QFN
28-Lead (4mm
×
5mm) Plastic QFN
28-Lead Plastic SSOP
28-Lead Plastic SSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–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/
38581fd
2
LTC3858-1
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN
V
FB1,2
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
RUN1,2
= 5V, EXTV
CC
= 0V unless
otherwise noted.
CONDITIONS
(Note 4) I
TH1,2
= 1.2V
–40°C to 125°C
–40°C to 85°C
(Note 4)
(Note 4) V
IN
= 4.5V to 38V
(Note4)
Measured in Servo Loop,
∆I
TH
Voltage = 1.2V to 0.7V
(Note4)
Measured in Servo Loop,
∆I
TH
Voltage = 1.2V to 2V
(Note 4) I
TH1,2
= 1.2V, Sink/Source = 5μA
(Note 5)
RUN1 = 5V and RUN2 = 0V V
FB1
= 0.83V (No Load) or
,
RUN1 = 0V and RUN2 = 5V, V
FB2
= 0.83V (No Load)
RUN1,2 = 5V, V
FB1,2
= 0.83V (No Load)
RUN1 = 5V and RUN2 = 0V V
FB1
= 0.83V (No Load) or
,
RUN1 = 0V and RUN2 = 5V, V
FB2
= 0.83V (No Load)
RUN1,2 = 5V, V
FB1,2
= 0.83V (No Load)
RUN1,2 = 0V
INTV
CC
Ramping Up
INTV
CC
Ramping Down
Measured at V
FB1,2
, Relative to Regulated V
FB1,2
Each Channel
Each Channel
V
OUT1,2
< INTV
CC
– 0.5V
V
OUT1,2
> INTVCC + 0.5V
In Dropout, FREQ = 0V
V
SS1,2
= 0V
V
RUN1
, V
RUN2
Rising
V
SS1
, V
SS2
Rising from 1V
V
SS1
, V
SS2
Rising from 2V
Short-Circuit Condition V
FB1,2
= 0V
V
SS1,2
= 5V
V
FB1,2
= 0.7V, V
SENSE1
–,
2
– = 3.3V
MIN
4
l
TYP
MAX
38
0.812
0.808
±50
0.02
0.1
UNITS
V
V
V
nA
%/V
%
0.788
0.792
I
FB1,2
V
REFLNREG
V
LOADREG
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
0.800
0.800
±5
0.002
0.01
l
l
–0.01
2
1.3
2
170
300
8
4.0
3.8
10
–0.1
%
mmho
mA
mA
g
m1,2
I
Q
Transconductance Amplifier g
m
Input DC Supply Current
Pulse Skip or Forced Continuous Mode
(One Channel On)
Pulse Skip or Forced Continuous Mode
(Both Channels On)
Sleep Mode (One Channel On)
Sleep Mode (Both Channels On)
Shutdown
Undervoltage Lockout
Feedback Overvoltage Protection
SENSE
+
Pin Current
SENSE
–
Pin Current
250
450
20
4.2
4.0
13
±1
±1
950
1.4
1.33
2.1
1.7
13
57
μA
μA
μA
V
V
%
μA
μA
μA
%
μA
V
mV
V
V
μA
mV
UVLO
V
OVL
I
SENSE+
I
SENSE–
l
l
3.6
7
DF
MAX
I
SS1,2
V
RUN1,2
On
V
RUN1,2
Hyst
V
SS1,2
LA
V
SS1,2
LT
I
DSC1,2
LT
V
SENSE(MAX)
Gate Driver
TG1,2
BG1,2
Maximum Duty Factor
Soft-Start Charge Current
RUN Pin On Threshold Voltage
RUN Pin Hysteresis Voltage
SS Pin Latchoff Arming Threshold
Voltage
SS Pin Latchoff Threshold Voltage
SS Discharge Current
Maximum Current Sense Threshold
Voltage
Pull-Up On-Resistance
Pull-Down On-Resistance
Pull-Up On-Resistance
Pull-Down On-Resistance
TG Transistion Time:
Rise Time
Fall Time
l
98
0.7
1.23
1.9
1.3
7
550
99.4
1.0
1.28
50
2
1.5
10
50
l
43
2.5
1.5
2.4
1.1
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
25
16
Ω
Ω
Ω
Ω
ns
ns
TG1,2 t
r
TG1,2 t
f
38581fd
3
LTC3858-1
ELECTRICAL CHARACTERISTICS
PARAMETER
BG Transistion Time:
BG1,2 t
r
Rise Time
Fall Time
BG1,2 t
f
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
BG/TG t
1D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
t
ON(MIN)
Minimum On-Time
INTV
CC
Linear Regulator
V
INTVCCVIN
Internal V
CC
Voltage
V
LDOVIN
INTV
CC
Load Regulation
V
INTVCCEXT
Internal V
CC
Voltage
V
LDOEXT
INTV
CC
Load Regulation
V
EXTVCC
EXTV
CC
Switchover Voltage
V
LDOHYS
EXTV
CC
Hysteresis Voltage
Oscillator and Phase-Locked Loop
f
25kΩ
Programmable Frequency
f
65kΩ
Programmable Frequency
f
105kΩ
Programmable Frequency
f
LOW
Low Fixed Frequency
f
HIGH
High Fixed Frequency
f
SYNC
Synchronizable Frequency
PGOOD1 Output
V
PGL
PGOOD1 Voltage Low
I
PGOOD
PGOOD1 Leakage Current
V
PG
PGOOD1 Trip Level
SYMBOL
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
RUN1,2
= 5V, EXTV
CC
= 0V unless
otherwise noted.
CONDITIONS
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
C
LOAD
= 3300pF Each Driver
C
LOAD
= 3300pF Each Driver
(Note 7)
6V < V
IN
< 38V, V
EXTVCC
= 0V
I
CC
= 0mA to 50mA, V
EXTVCC
= 0V
6V < V
EXTVCC
< 13V
I
CC
= 0mA to 50mA, V
EXTVCC
= 8.5V
EXTV
CC
Ramping Positive
4.85
4.85
4.5
MIN
TYP
28
13
30
30
95
5.1
0.7
5.1
0.6
4.7
250
105
440
835
350
535
5.35
1.1
5.35
1.1
4.9
MAX
UNITS
ns
ns
ns
ns
ns
V
%
V
%
V
mV
kHz
kHz
kHz
kHz
kHz
kHz
V
μA
%
%
%
%
μs
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
I
PGOOD
= 2mA
V
PGOOD
= 5V
V
FB
with Respect to Set Regulated Voltage
V
FB
Ramping Negative
Hysteresis
V
FB
with Respect to Set Regulated Voltage
V
FB
Ramping Positive
Hysteresis
375
320
485
75
505
380
585
850
0.4
±1
–7
l
0.2
–13
–10
2.5
10
2.5
25
7
13
t
PG
Delay for Reporting a Fault (PGOOD Low)
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Ratings for extended periods may affect device reliability and
lifetime.
Note 2:
The LTC3858-1 is tested under pulsed conditions such that
T
J
≈ T
A
. The LTC3858E-1 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 LTC3858I-1 is guaranteed
over the full –40°C to 125°C operating junction temperature range.
Note that the maximum ambient temperature is determined by specific
operating conditions in conjunction with board layout, the rated package
thermal resistance and other environmental factors.
Note 3:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
T
J
= T
A
+ (P
D
•
θ
JA
)
where
θ
JA
= 43°C/W for the QFN package and
θ
JA
= 90°C/W for the SSOP
package.
Note 4:
The LTC3858-1 is tested in a feedback loop that servos V
ITH1,2
to
a specified voltage and measures the resultant V
FB1,2
. The specification at
85°C is not tested in production. This specification is assured by design,
characterization and correlation to production testing at 125°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-
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