Datasheet
3
LTC3727/LTC3727-1
3727fc
The ● 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.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
LOADREG
Output Voltage Load Regulation (Note 4)
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 0.7V ● 0.1 0.5 %
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 2.0V ● –0.1 –0.5 %
g
m1, 2
Transconductance Amplifier g
m
I
TH1, 2
= 1.2V; Sink/Source 5μA (Note 4) 1.3 mmho
g
mGBW1, 2
Transconductance Amplifier GBW I
TH1, 2
= 1.2V (Note 4) 3 MHz
I
Q
Input DC Supply Current (Note 5)
Normal Mode V
IN
= 15V, EXTV
CC
Tied to V
OUT1
, V
OUT1
= 8.5V 670 μA
Shutdown V
RUN/SS1, 2
= 0V 20 35 μA
V
FCB
Forced Continuous Threshold ● 0.76 0.800 0.84 V
I
FCB
Forced Continuous Pin Current V
FCB
= 0.85V – 0.30 – 0.18 – 0.05 μA
V
BINHIBIT
Burst Inhibit (Constant Frequency) Measured at FCB pin 6.8 7.3 V
Threshold
UVLO Undervoltage Lockout V
IN
Ramping Down ● 3.5 4 V
V
OVL
Feedback Overvoltage Lockout Measured at V
OSENSE1, 2
● 0.84 0.86 0.88 V
I
SENSE
Sense Pins Total Source Current (Each Channel) V
SENSE1
–
, 2
–
= V
SENSE1
+
, 2
+
= 0V – 85 – 60 μA
DF
MAX
Maximum Duty Factor In Dropout 98 99.4 %
I
RUN/SS1, 2
Soft-Start Charge Current V
RUN/SS1, 2
= 1.9V 0.5 1.2 μA
V
RUN/SS1, 2
ON RUN/SS Pin ON Threshold V
RUN/SS1,
V
RUN/SS2
Rising 1.0 1.5 1.9 V
V
RUN/SS1, 2
LT RUN/SS Pin Latchoff Arming Threshold V
RUN/SS1,
V
RUN/SS2
Rising from 3V (LTC3727 Only) 4.1 4.5 V
I
SCL1, 2
RUN/SS Discharge Current Soft-Short Condition V
OSENSE1, 2
= 0.5V, 0.5 2 4 μA
V
RUN/SS1, 2
= 4.5V (LTC 3727 Only)
I
SDLHO
Shutdown Latch Disable Current V
OSENSE1, 2
= 0.5V (LTC3727 Only) 1.6 5 μA
V
SENSE(MAX)
Maximum Current Sense Threshold V
OSENSE1, 2
= 0.7V,V
SENSE1
–
, 2
– = 12V ● 105 135 165 mV
TG Transition Time: (Note 6)
TG1, 2 t
r
Rise Time C
LOAD
= 3300pF 50 90 ns
TG1, 2 t
f
Fall Time C
LOAD
= 3300pF 50 90 ns
BG Transition Time: (Note 6)
BG1, 2 t
r
Rise Time C
LOAD
= 3300pF 40 90 ns
BG1, 2 t
f
Fall Time C
LOAD
= 3300pF 40 80 ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay C
LOAD
= 3300pF Each Driver 90 ns
Synchronous Switch-On Delay Time
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay C
LOAD
= 3300pF Each Driver 90 ns
Top Switch-On Delay Time
t
ON(MIN)
Minimum On-Time Tested with a Square Wave (Note 7) 180 ns
INTV
CC
Linear Regulator
V
INTVCC
Internal V
CC
Voltage 8.5V < V
IN
< 30V, V
EXTVCC
= 6V 7.2 7.5 7.8 V
V
LDO
INT INTV
CC
Load Regulation I
CC
= 0mA to 20mA, V
EXTVCC
= 6V 0.2 1.0 %
V
LDO
EXT EXTV
CC
Voltage Drop I
CC
= 20mA, V
EXTVCC
= 8.5V 70 160 mV
V
EXTVCC
EXTV
CC
Switchover Voltage I
CC
= 20mA, EXTV
CC
Ramping Positive ● 6.9 7.3 V
V
LDOHYS
EXTV
CC
Hysteresis 0.3 V
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency V
PLLFLTR
= 1.2V 350 380 430 kHz
f
LOW
Lowest Frequency V
PLLFLTR
= 0V 220 255 290 kHz
f
HIGH
Highest Frequency V
PLLFLTR
≥ 2.4V 460 530 580 kHz