Datasheet

LTC3859A
4
3859af
elecTrical characTerisTics
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
BIAS
= 12V, V
RUN1,2,3
= 5V, EXTV
CC
= 0V unless otherwise
noted. (Note 2)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
Q
Input DC Supply Current (Note 5)
Pulse-Skipping or
Forced Continuous Mode
(One Channel On)
RUN1 = 5V and RUN2,3 = 0V or
RUN2 = 5V and RUN1,3 = 0V or
RUN3 = 5V and RUN1,2 = 0V
V
FB1, 2
ON = 0.83V (No Load)
V
FB3
= 1.25V
1.5 mA
Pulse-Skipping or
Forced Continuous Mode
(All Channels On)
RUN1,2,3 = 5V,
V
FB1,2
= 0.83V (No Load)
V
FB3
= 1.25V
3 mA
Sleep Mode
(One Channel On, Buck)
RUN1 = 5V and RUN2,3 = 0V or
RUN2 = 5V and RUN1,3 = 0V
V
FB,ON
= 0.83V (No Load)
55 80 µA
Sleep Mode
(One Channel On, Boost)
RUN3 = 5V and RUN1,2 = 0V
V
FB3
= 1.25V
55 80 µA
Sleep Mode
(Buck and Boost Channel On)
RUN1 = 5V and RUN2 = 0V or
RUN2 = 5V and RUN1 = 0V
RUN3 = 5V
V
FB1,2
= 0.83V (No Load)
V
FB3
= 1.25V
65 100 µA
Sleep Mode
(All Three Channels On)
RUN1,2,3 = 5V,
V
FB1,2
= 0.83V (No Load)
V
FB3
= 1.25V
80 120 µA
Shutdown RUN1,2,3 = 0V 14 30 µA
UVLO Undervoltage Lockout INTV
CC
Ramping Up
l
4.15 4.5 V
INTV
CC
Ramping Down
l
3.5 3.8 4.0 V
V
OVL1,2
Buck Feedback Overvoltage Protection Measured at V
FB1,2
Relative to
Regulated V
FB1,2
7 10 13 %
I
SENSE1,2
+ SENSE
+
Pin Current Bucks (Channels 1 and 2) ±1 µA
I
SENSE3
+ SENSE
+
Pin Current Boost (Channel 3) 170 µA
I
SENSE1,2
– SENSE
–
Pin Current Bucks (Channels 1 and 2)
V
OUT1,2
< V
INTVCC
– 0.5V
V
OUT1,2
> V
INTVCC
+ 0.5V 700
±2 µA
µA
I
SENSE3
– SENSE
–
Pin Current Boost (Channel 3)
V
SENSE3
+, V
SENSE3
– = 12V
±1 µA
DF
MAX,TG
Maximum Duty Factor for TG Bucks (Channels 1,2) in Dropout, FREQ = 0V
Boost (Channel 3) in Overvoltage
98 99
100
%
%
DF
MAX,BG
Maximum Duty Factor for BG Bucks (Channels 1,2) in Overvoltage
Boost (Channel 3)
100
96
%
%
I
TRACK/SS1,2
Soft-Start Charge Current V
TRACK/SS1,2
= 0V 0.7 1.0 1.4 µA
I
SS3
Soft-Start Charge Current V
SS3
= 0V 0.7 1.0 1.4 µA
V
RUN1
ON
V
RUN2,3
ON
RUN1 Pin Threshold
RUN2,3 Pin Threshold
V
RUN1
Rising
V
RUN2,3
Rising
l
l
1.19
1.23
1.25
1.28
1.31
1.33
V
V
V
RUN1,2,3
Hyst RUN Pin Hysteresis 80 mV
V
SENSE1,2,3(MAX)
Maximum Current Sense Threshold V
FB1,2
= 0.7V, V
SENSE1,2
– = 3.3V
V
FB1,2,3
= 1.1V, V
SENSE3
+ = 12V
l
43 50 57 mV
V
SENSE3(CM)
SENSE3 Pins Common Mode Range
(BOOST Converter Input Supply Voltage)
2.5 38 V