LTC3780
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TA = 25°C. VIN = 15V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
99
MAX
UNITS
%
DF MAX, Boost
DF MAX, Buck
Maximum Duty Factor
Maximum Duty Factor
RUN Pin On Threshold
Soft-Start Charge Current
Maximum Current Sense Threshold
% Switch C On
% Switch A On (in Dropout)
99
%
V
V
RUN
V
RUN
Rising
= 2V
1
1.5
1.2
2
V
RUN(ON)
I
0.5
μA
SS
l
l
V
Boost: V
= V – 50mV
REF
160
–110
185
–150
mV
mV
SENSE(MAX)
OSENSE
OSENSE
REF
Buck: V
= V – 50mV
–95
V
Minimum Current Sense Threshold
TG Rise Time
Discontinuous Mode
–6
50
45
45
55
80
mV
ns
ns
ns
ns
ns
SENSE(MIN,BUCK)
TG1, TG2 t
TG1, TG2 t
C
LOAD
C
LOAD
C
LOAD
C
LOAD
C
LOAD
= 3300pF (Note 5)
= 3300pF (Note 5)
= 3300pF (Note 5)
= 3300pF (Note 5)
= 3300pF Each Driver
r
TG Fall Time
f
BG1, BG2 t
BG1, BG2 t
BG Rise Time
r
BG Fall Time
f
TG1/BG1 t
BG1/TG1 t
TG2/BG2 t
BG2/TG2 t
Mode
TG1 Off to BG1 On Delay,
Switch C On Delay
1D
BG1 Off to TG1 On Delay,
Synchronous Switch D On Delay
C
LOAD
C
LOAD
C
LOAD
C
LOAD
C
LOAD
= 3300pF Each Driver
= 3300pF Each Driver
= 3300pF Each Driver
= 3300pF Each Driver
= 3300pF Each Driver
80
80
ns
ns
ns
ns
ns
ns
ns
2D
3D
4D
TG2 Off to BG2 On Delay,
Synchronous Switch B On Delay
BG2 Off to TG2 On Delay,
Switch A On Delay
80
BG1 Off to BG2 On Delay,
Switch A On Delay
250
250
200
180
Transition 1
Mode
Transition 2
BG2 Off to BG1 On Delay,
Synchronous Switch D On Delay
t
Minimum On-Time for Main Switch in
Boost Operation
Switch C (Note 6)
Switch B (Note 6)
ON(MIN,BOOST)
ON(MIN,BUCK)
t
Minimum On-Time for Synchronous
Switch in Buck Operation
Internal V Regulator
CC
l
l
V
Internal V Voltage
7V < V < 30V, V = 5V
EXTVCC
5.7
5.4
6
6.3
2
V
%
INTVCC
CC
IN
Internal V Load Regulation
I
CC
I
CC
= 0mA to 20mA, V = 5V
EXTVCC
0.2
5.7
300
150
∆V
CC
LDO(LOADREG)
V
EXTV Switchover Voltage
= 20mA, V
Rising
V
EXTVCC
CC
EXTVCC
EXTVCC
EXTV Switchover Hysteresis
mV
mV
∆V
∆V
CC
EXTVCC(HYS)
EXTV Switch Drop Voltage
I
CC
= 20mA, V
= 6V
300
CC
EXTVCC
Oscillator and Phase-Locked Loop
f
f
f
Nominal Frequency
V
V
V
= 1.2V
= 0V
260
170
340
300
200
400
50
330
220
440
kHz
kHz
kHz
kΩ
NOM
LOW
HIGH
PLLFLTR
PLLFLTR
PLLFLTR
Lowest Frequency
Highest Frequency
= 2.4V
R
PLLIN Input Resistance
Phase Detector Output Current
PLLIN
I
f
f
< f
> f
–15
15
μA
μA
PLLLPF
PLLIN
PLLIN
OSC
OSC
(Note 9)
3780fe
4
Linear Systems [ Linear Systems ]
