LT8708
4
Rev 0
For more information
ELECTRICAL CHARACTERISTICS
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
INCHIP
= 12V,
SHDN
= 3V, DIR = 3.3V unless otherwise noted (Note 3).
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Voltage Supplies and Regulators
V
INCHIP
Operating Voltage Range
EXTV
CC
= 0V
EXTV
CC
= 7.5V
l
l
5.5
2.8
80
80
V
V
V
INCHIP
Quiescent Current
Not Switching, V
EXTVCC
= 0V
SWEN
= 3.3V
SWEN
= 0V
3.9
2.45
6.5
4.5
mA
mA
V
INCHIP
Quiescent Current in Shutdown
V
SHDN
= 0V
0
1
μA
EXTV
CC
Switchover Voltage
I
INTVCC
= –20mA, V
EXTVCC
Rising
l
6.15
6.4
6.6
V
EXTV
CC
Switchover Hysteresis
0.2
V
INTV
CC
Current Limit
Maximum Current Draw from INTV
CC
and LDO33 Pins
Combined. Regulated from V
INCHIP
or EXTV
CC
(12V)
INTV
CC
= 5.25V
INTV
CC
= 4.4V
l
l
90
28
127
42
165
55
mA
mA
INTV
CC
Voltage
Regulated from V
INCHIP
, I
INTVCC
= 20mA
Regulated from EXTV
CC
(12V), I
INTVCC
= 20mA
l
l
6.1
6.1
6.3
6.3
6.5
6.5
V
V
INTV
CC
Load Regulation
I
INTVCC
= 0mA to 50mA
–0.5
–1.5
%
INTV
CC
, GATEV
CC
Undervoltage Lockout
INTV
CC
Falling, GATEV
CC
Connected to INTV
CC
l
4.45
4.65
4.85
V
INTV
CC
, GATEV
CC
Undervoltage Lockout Hysteresis
GATEV
CC
Connected to INTV
CC
170
mV
INTV
CC
Regulator Dropout Voltage
V
INCHIP
– V
INTVCC
, I
INTVCC
= 20mA
220
mV
LDO33 Pin Voltage
5mA from LDO33 Pin
l
3.23
3.295
3.35
V
LDO33 Pin Load Regulation
I
LDO33
= 0.1mA to 5mA
–0.25
–1
%
LDO33 Pin Current Limit
SYNC = 3V
l
12
17.25
22
mA
LDO33 Pin Undervoltage Lockout
LDO33 Falling
2.96
3.04
3.12
V
LDO33 Pin Undervoltage Lockout Hysteresis
35
mV
Switching Regulator Control
Maximum Current Sense Threshold (V
CSP
– V
CSN
)
Boost Mode, Minimum M3 Switch Duty Cycle
l
76
93
110
mV
Maximum Current Sense Threshold (V
CSN
– V
CSP
)
Buck Mode, Minimum M2 Switch Duty Cycle
l
68
82
97
mV
Maximum Current Sense Threshold (V
CSN
– V
CSP
)
Boost Mode, Minimum M3 Switch Duty Cycle
l
79
93
108
mV
Maximum Current Sense Threshold (V
CSP
– V
CSN
)
Buck Mode, Minimum M2 Switch Duty Cycle
l
72
84
96
mV
Gain from V
C
to Maximum Current Sense Voltage
(V
CSP
– V
CSN
) (A5 in the Block Diagram)
Boost Mode
Buck Mode
135
–135
mV/V
mV/V
SHDN
Input Voltage High
SHDN
Rising to Enable the Device
l
1.175
1.221
1.275
V
SHDN
Input Voltage High Hysteresis
40
mV
SHDN
Input Voltage Low
Device Disabled, Low Quiescent Current
(LT8708E, LT8708I)
(LT8708H)
l
l
0.35
0.3
V
V
SHDN
Pin Bias Current
V
SHDN
= 3V
V
SHDN
= 12V
0
14
1
22
μA
μA
SWEN Rising Threshold Voltage
l
1.156
1.208
1.256
V
SWEN Threshold Voltage Hysteresis
22
mV
SWEN Output Voltage Low
I
SWEN
= 200μA
SHDN
= 0V or V
INCHIP
= 0V
SHDN
= 3V
l
l
0.9
0.2
1.1
0.5
V
V
