Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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/
3728fg
2
TG1
NC
LTC3728
ELECTRICAL CHARACTERISTICS
SYMBOL
V
OSENSE1, 2
I
OSENSE1, 2
V
REFLNREG
V
LOADREG
PARAMETER
Regulated Feedback Voltage
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
Main Control Loops
(Note 3); I
TH1, 2
Voltage = 1.2V
(Note 3)
V
IN
= 3.6V to 30V (Note 3)
(Note 3)
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 0.7V
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 2.0V
I
TH1, 2
= 1.2V; Sink/Source 5μA (Note 3)
I
TH1, 2
= 1.2V (Note 3)
(Note 4)
V
IN
= 15V; EXTV
CC
Tied to V
OUT1
; V
OUT1
= 5V
V
RUN/SS1, 2
= 0V
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
RUN/SS1, 2
= 5V unless otherwise noted.
CONDITIONS
MIN
0.792
TYP
0.800
–5
0.002
0.1
–0.1
1.3
3
450
20
0.76
–0.50
0.800
–0.18
4.3
l
l
MAX UNITS
0.808
–50
0.02
0.5
–0.5
V
nA
%/V
%
%
mmho
MHzI
Q
μA
μA
V
μA
V
V
V
μA
%
μA
1.9
4.5
4
5
85
88
90
90
90
80
V
V
μA
μA
mV
mV
ns
ns
ns
ns
ns
ns
ns
5.2
1.0
160
V
%
mV
3728fg
g
m1, 2
g
mGBW1, 2
Transconductance Amplifier g
m
Transconductance Amplifier GBW
Input DC Supply Current
Normal Mode
Shutdown
35
0.84
–0.1
4.8
4
0.88
V
FCB
I
FCB
V
BINHIBIT
UVLO
V
OVL
I
SENSE
DF
MAX
I
RUN/SS1, 2
V
RUN/SS1, 2
ON
V
RUN/SS1, 2
LT
I
SCL1, 2
I
SDLHO
V
SENSE(MAX)
Forced Continuous Threshold
Forced Continuous Pin Current
Burst Inhibit (Constant-Frequency)
Threshold
Undervoltage Lockout
Feedback Overvoltage Lockout
Sense Pins Total Source Current
Maximum Duty Factor
Soft-Start Charge Current
RUN/SS Pin ON Threshold
RUN/SS Pin Latchoff Arming
Threshold
RUN/SS Discharge Current
Shutdown Latch Disable Current
Maximum Current Sense Threshold
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
Voltage Drop
V
FCB
= 0.85V
Measured at FCB Pin
V
IN
Ramping Down
Measured at V
OSENSE1, 2
(Each Channel); V
SENSE1
–
, 2
– = V
SENSE1
+
, 2
+ = 0V
In Dropout
V
RUN/SS1, 2
= 1.9V
V
RUN/SS1,
V
RUN/SS2
Rising
V
RUN/SS1,
V
RUN/SS2
Rising from 3V
Soft-Short Condition V
OSENSE1, 2
= 0.5V;
V
RUN/SS1, 2
= 4.5V
V
OSENSE1, 2
= 0.5V
V
OSENSE1, 2
= 0.7V, V
OSENSE1
–
, 2
– = 5V
V
OSENSE1, 2
= 0.7V, V
OSENSE1
–
, 2
– = 5V
(Note 5)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
(Note 5)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
C
LOAD
= 3300pF Each Driver
C
LOAD
= 3300pF Each Driver
Tested with a Square Wave (Note 6)
6V < V
IN
< 30V, V
EXTVCC
= 4V
I
CC
= 0 to 20mA, V
EXTVCC
= 4V
I
CC
= 20mA, V
EXTVCC
= 5V
3.5
0.84
–85
98
0.5
1.0
0.86
–60
99.4
1.2
1.5
3.8
0.5
2
1.6
l
65
62
75
75
50
50
40
40
90
90
100
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
LDO
EXT
INTV
CC
Linear Regulator
48
5.0
0.2
80
3
LTC3728
ELECTRICAL CHARACTERISTICS
SYMBOL
V
EXTVCC
V
LDOHYS
f
NOM
f
LOW
f
HIGH
R
PLLIN
I
PLLFLTR
PARAMETER
EXTV
CC
Switchover Voltage
EXTV
CC
Hysteresis
Nominal Frequency
Lowest Frequency
Highest Frequency
PLLIN Input Resistance
Phase Detector Output Current
Sinking Capability
Sourcing Capability
3.3V Regulator Output Voltage
3.3V Regulator Load Regulation
3.3V Regulator Line Regulation
Leakage Current of 3.3V Regulator in
Shutdown
PGOOD Voltage Low
PGOOD Leakage Current
PGOOD Trip Level, Either Controller
f
PLLIN
< f
OSC
f
PLLIN
> f
OSC
No Load
I
3.3
= 0 to 10mA
6V < V
IN
< 30V
V
RUN/SS1, 2
= 0V, V
IN
= 25V
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
RUN/SS1, 2
= 5V unless otherwise noted.
CONDITIONS
I
CC
= 20mA, EXTV
CC
Ramping Positive
l
MIN
4.5
TYP
4.7
0.2
MAX UNITS
V
V
440
290
590
kHz
kHz
kHz
kΩ
μA
μA
3.45
2
0.2
50
V
%
%
μA
Oscillator and Phase-Locked Loop
V
PLLFLTR
= 1.2V
V
PLLFLTR
= 0V
V
PLLFLTR
≥ 2.4V
360
230
480
400
260
550
50
–15
15
3.25
3.35
0.5
0.05
10
3.3V Linear Regulator
V
3.3OUT
V
3.3IL
V
3.3VL
I
3.3LEAK
PGOOD Output
V
PGL
I
PGOOD
V
PG
I
PGOOD
= 2mA
V
PGOOD
= 5V
V
OSENSE
with Respect to Set Output Voltage
V
OSENSE
Ramping Negative
V
OSENSE
Ramping Positive
–6
6
–7.5
7.5
0.1
0.3
±1
–9.5
9.5
V
μA
%
%
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:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC3728: T
J
= T
A
+ (P
D
• 95 °C/W)
Note 3:
The LTC3728 is tested in a feedback loop that servos V
ITH1, 2
to a
specified voltage and measures the resultant V
OSENSE1, 2.
Note 4:
Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 5:
Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 6:
The IC minimum on-time is tested under an ideal condition
without external power FETs. It can be different when the IC is working in
an actual circuit. See Minimum On-Time Considerations in the Application
Information section.
Note 7:
The LTC3728E is 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 LTC3728I is guaranteed to meet
performance specifications over the full –40°C to 85°C operating
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