Datasheet

LTC3787
3
3787fc
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C, VBIAS = 12V, unless otherwise noted (Note 2).
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loop
VBIAS Chip Bias Voltage Operating Range 4.5 38 V
V
FB
Regulated Feedback Voltage I
TH
= 1.2V (Note 4)
l
1.188 1.200 1.212 V
I
FB
Feedback Current (Note 4) ±5 ±50 nA
V
REFLNREG
Reference Line Voltage Regulation VBIAS = 6V to 38V 0.002 0.02 %/V
V
LOADREG
Output Voltage Load Regulation
(Note 4)
Measured in Servo Loop;
∆I
TH
Voltage = 1.2V to 0.7V
l
0.01 0.1 %
Measured in Servo Loop;
∆I
TH
Voltage = 1.2V to 2V
l
–0.01 –0.1 %
g
m
Error Amplifier Transconductance I
TH
= 1.2V 2 mmho
I
Q
Input DC Supply Current
Pulse-Skipping or Forced Continuous Mode
Sleep Mode
Shutdown
(Note 5)
RUN = 5V; V
FB
= 1.25V (No Load)
RUN = 5V; V
FB
= 1.25V (No Load)
RUN = 0V
1.2
135
8
300
20
mA
µA
µA
UVLO INTV
CC
Undervoltage Lockout Thresholds V
INTVCC
Ramping Up
V
INTVCC
Ramping Down
l
l
3.6
4.1
3.8
4.3 V
V
V
RUN
RUN Pin ON Threshold V
RUN
Rising
l
1.18 1.28 1.38 V
V
RUNHYS
RUN Pin Hysteresis 100 mV
I
RUNHYS
RUN Pin Hysteresis Current V
RUN
> 1.28V 4.5 µA
I
RUN
RUN Pin Current V
RUN
< 1.28V 0.5 µA
I
SS
Soft-Start Charge Current V
SS
= GND 7 10 13 µA
V
SENSE1,2(MAX)
Maximum Current Sense Threshold V
FB
= 1.1V, I
LIM
= INTV
CC
V
FB
= 1.1V, I
LIM
= Float
V
FB
= 1.1V, I
LIM
= GND
l
l
l
90
68
42
100
75
50
110
82
56
mV
mV
mV
V
SENSE(MATCH)
Matching Between V
SENSE1(MAX)
and
V
SENSE2(MAX)
V
FB
= 1.1V, I
LIM
= INTV
CC
V
FB
= 1.1V, I
LIM
= Float
V
FB
= 1.1V, I
LIM
= GND
l
l
l
–12
–10
–9
0
0
0
12
10
9
mV
mV
mV
V
SENSE(CM)
SENSE Pins Common Mode Range (BOOST
Converter Input Supply Voltage V
IN
)
2.5 38 V
I
SENSE1,2
+
SENSE
+
Pin Current V
FB
= 1.1V, I
LIM
= Float 200 300 µA
I
SENSE1,2
–
SENSE
–
Pin Current V
FB
= 1.1V, I
LIM
= Float ±1 µA
t
r(TG1,2)
Top Gate Rise Time C
LOAD
= 3300pF (Note 6) 20 ns
t
f(TG1,2)
Top Gate Fall Time C
LOAD
= 3300pF (Note 6) 20 ns
t
r(BG1,2)
Bottom Gate Rise Time C
LOAD
= 3300pF (Note 6) 20 ns
t
r(BG1,2)
Bottom Gate Fall Time C
LOAD
= 3300pF (Note 6) 20 ns
R
UP(TG1,2)
Top Gate Pull-Up Resistance 1.2 
R
DN(TG1,2)
Top Gate Pull-Down Resistance 1.2 
R
UP(TG1,2)
Bottom Gate Pull-Up Resistance 1.2 
R
DN(TG1,2)
Bottom Gate Pull-Down Resistance 1.2 
t
D(TG/BG)
Top Gate Off to Bottom Gate On Switch-On
Delay Time
C
LOAD
= 3300pF (Each Driver) 70 ns
t
D(BG/TG)
Bottom Gate Off to Top Gate On Switch-On
Delay Time
C
LOAD
= 3300pF (Each Driver) 70 ns
DF
BG1,2(MAX)
Maximum BG Duty Factor 96 %
t
ON(MIN)
Minimum BG On-Time (Note 7) 110 ns