Datasheet
LTC3827
3
3827ff
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 12V, V
RUN/SS1, 2
= 5V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
V
FB1, 2
Regulated Feedback Voltage (Note 4) I
TH1, 2
Voltage = 1.2V
●
0.792 0.800 0.808 V
I
VFB1, 2
Feedback Current (Note 4) –5 –50 nA
V
REFLNREG
Reference Voltage Line Regulation V
IN
= 4V to 30V (Note 4) 0.002 0.02 %/V
V
LOADREG
Output Voltage Load Regulation (Note 4)
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 0.7V
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 2V
●
●
0.1
–0.1
0.5
–0.5
%
%
g
m1, 2
Transconductance Amplifi er g
m
I
TH1, 2
= 1.2V; Sink/Source 5µA (Note 4) 1.55 mmho
I
Q
Input DC Supply Current
Sleep Mode (Channel 1 On)
Sleep Mode (Channel 2 On)
Shutdown
Sleep Mode (Both Channels)
(Note 5)
RUN1 = 5V, RUN2 = 0V, V
FB1
= 0.83V (No Load)
RUN1 = 0V, RUN2 = 5V, V
FB2
= 0.83V (No Load)
V
RUN1, 2
= 0V
RUN1,2 = 5V, V
FB1
= V
FB2
= 0.83V
80
80
8
115
125
125
20
160
µA
µA
µA
µA
UVLO Undervoltage Lockout V
IN
Ramping Down
●
3.5 4 V
V
OVL
Feedback Overvoltage Lockout Measured at V
FB1, 2
, Relative to Regulated V
FB1, 2
81012 %
I
SENSE
Sense Pins Total Source Current (Each Channel) V
SENSE1
–
, 2
–
= V
SENSE1
+
, 2
+
= 0V –660 µA
DF
MAX
Maximum Duty Factor In Dropout 98 99.4 %
I
TRACK/SS1, 2
Soft-Start Charge Current V
TRACK1, 2
= 0V 0.75 1.0 1.35 µA
V
RUN1, 2
ON RUN Pin ON Threshold V
RUN1,
V
RUN2
Rising 0.5 0.7 0.9 V
V
SENSE(MAX)
Maximum Current Sense Threshold V
FB1, 2
= 0.7V,V
SENSE1
–
, 2
– = 3.3V
V
FB1, 2
= 0.7V,V
SENSE1
–
, 2
– = 3.3V
●
90
80
100
100
110
115
mV
mV
TG1, 2 t
r
TG1, 2 t
f
TG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
50
50
90
90
ns
ns
BG1, 2 t
r
BG1, 2 t
f
BG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
40
40
90
80
ns
ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
C
LOAD
= 3300pF Each Driver 70 ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
C
LOAD
= 3300pF Each Driver 70 ns
t
ON(MIN)
Minimum On-Time (Note 7) 180 ns
INTV
CC
Linear Regulator
V
INTVCCVIN
Internal V
CC
Voltage 8.5V < V
IN
< 30V, V
EXTVCC
= 0V 5.0 5.25 5.5 V
V
LDOVIN
INTV
CC
Load Regulation I
CC
= 0mA to 20mA, V
EXTVCC
= 0V 0.2 1.0 %
V
INTVCCEXT
Internal V
CC
Voltage V
EXTVCC
= 8.5V 7.2 7.5 7.8 V
V
LDOEXT
INTV
CC
Load Regulation I
CC
= 0mA to 20mA, V
EXTVCC
= 8.5V 0.2 1.0 %
V
EXTVCC
EXTV
CC
Switchover Voltage EXTV
CC
Ramping Positive
4.5 4.7 V
V
LDOHYS
EXTV
CC
Hysteresis 0.2 V
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency V
PLLLPF
= Floating; PLLIN/MODE = DC Voltage 360 400 440 kHz
f
LOW
Lowest Frequency V
PLLLPF
= 0V; PLLIN/MODE = DC Voltage 220 250 280 kHz
f
HIGH
Highest Frequency V
PLLLPF
= INTV
CC
; PLLIN/MODE = DC Voltage 475 530 580 kHz
f
SYNCMIN
Minimum Synchronizable Frequency PLLIN/MODE = External Clock; V
PLLLPF
= 0V 115 140 kHz