LT8708E (Notes 3, 8) ........................ –40°C to 125°C
LT8708I (Notes 3, 8) ......................... –40°C to 125°C
LT8708H (Notes 3, 8) ....................... –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
40 39 38 37 36 35
CLKOUT 1
SS 2
SHDN
3
CSN 4
CSP 5
ICN 6
DIR 7
FBIN 8
FBOUT 9
V
C
10
IMON_INP 11
IMON_INN 12
RT 13
SYNC 14
15 16 17 18
GND
BG1
GATEV
CC
BG2
28
ICP
27
VINHIMON
26
VOUTLOMON
25
RVSOFF
24 BOOST1
23 TG1
22 SW1
19 20 21
BOOST2
TG2
SW2
UHG PACKAGE
40-LEAD (5mm
×
8mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 36°C/W,
θ
JC
= 3.8°C/W
EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LT8708EUHG#PBF
LT8708IUHG#PBF
LT8708HUHG#PBF
TAPE AND REEL
LT8708EUHG#TRPBF
LT8708IUHG#TRPBF
LT8708HUHG#TRPBF
PART MARKING*
8708
8708
8708
PACKAGE DESCRIPTION
40-Lead (5mm × 8mm) Plastic QFN
40-Lead (5mm × 8mm) Plastic QFN
40-Lead (5mm × 8mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
Consult ADI Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
For more information
www.analog.com
3
Rev 0
LT8708
ELECTRICAL CHARACTERISTICS
PARAMETER
Voltage Supplies and Regulators
V
INCHIP
Operating Voltage Range
V
INCHIP
Quiescent Current
V
INCHIP
Quiescent Current in Shutdown
EXTV
CC
Switchover Voltage
EXTV
CC
Switchover Hysteresis
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
Regulated from V
INCHIP
, I
INTVCC
= 20mA
Regulated from EXTV
CC
(12V), I
INTVCC
= 20mA
I
INTVCC
= 0mA to 50mA
INTV
CC
Falling, GATEV
CC
Connected to INTV
CC
GATEV
CC
Connected to INTV
CC
V
INCHIP
– V
INTVCC
, I
INTVCC
= 20mA
5mA from LDO33 Pin
I
LDO33
= 0.1mA to 5mA
SYNC = 3V
LDO33 Falling
l
l
l
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).
CONDITIONS
EXTV
CC
= 0V
EXTV
CC
= 7.5V
Not Switching, V
EXTVCC
= 0V
SWEN = 3.3V
SWEN = 0V
V
SHDN
= 0V
I
INTVCC
= –20mA, V
EXTVCC
Rising
l
l
l
MIN
5.5
2.8
TYP
MAX
80
80
UNITS
V
V
mA
mA
μA
V
V
3.9
2.45
0
6.15
6.4
0.2
6.5
4.5
1
6.6
l
l
l
l
90
28
6.1
6.1
4.45
127
42
6.3
6.3
–0.5
4.65
170
220
165
55
6.5
6.5
–1.5
4.85
mA
mA
V
V
%
V
mV
mV
INTV
CC
Voltage
INTV
CC
Load Regulation
INTV
CC
, GATEV
CC
Undervoltage Lockout
INTV
CC
, GATEV
CC
Undervoltage Lockout Hysteresis
INTV
CC
Regulator Dropout Voltage
LDO33 Pin Voltage
LDO33 Pin Load Regulation
LDO33 Pin Current Limit
LDO33 Pin Undervoltage Lockout
LDO33 Pin Undervoltage Lockout Hysteresis
Switching Regulator Control
Maximum Current Sense Threshold (V
CSP
– V
CSN
)
Maximum Current Sense Threshold (V
CSN
– V
CSP
)
Maximum Current Sense Threshold (V
CSN
– V
CSP
)
Maximum Current Sense Threshold (V
CSP
– V
CSN
)
Gain from V
C
to Maximum Current Sense Voltage
(V
CSP
– V
CSN
) (A5 in the Block Diagram)
SHDN
Input Voltage High
SHDN
Input Voltage High Hysteresis
SHDN
Input Voltage Low
3.23
12
2.96
3.295
–0.25
17.25
3.04
35
3.35
–1
22
3.12
V
%
mA
V
mV
Boost Mode, Minimum M3 Switch Duty Cycle
Buck Mode, Minimum M2 Switch Duty Cycle
Boost Mode, Minimum M3 Switch Duty Cycle
Buck Mode, Minimum M2 Switch Duty Cycle
Boost Mode
Buck Mode
SHDN
Rising to Enable the Device
Device Disabled, Low Quiescent Current
(LT8708E, LT8708I)
(LT8708H)
V
SHDN
= 3V
V
SHDN
= 12V
l
l
l
l
76
68
79
72
93
82
93
84
135
–135
110
97
108
96
mV
mV
mV
mV
mV/V
mV/V
l
1.175
1.221
40
1.275
V
mV
l
l
0.35
0.3
0
14
1
22
1.256
V
V
μA
μA
V
mV
SHDN
Pin Bias Current
SWEN Rising Threshold Voltage
SWEN Threshold Voltage Hysteresis
SWEN Output Voltage Low
l
1.156
1.208
22
I
SWEN
= 200μA
SHDN
= 0V or V
INCHIP
= 0V
SHDN
= 3V
l
l
0.9
0.2
1.1
0.5
V
V
4
Rev 0
For more information
www.analog.com
LT8708
ELECTRICAL CHARACTERISTICS
PARAMETER
SWEN Internal Pull-Down Release Voltage
MODE Pin Continuous Conduction Mode (CCM)
Threshold
MODE Pin Hybrid DCM/CCM Mode (HCM) Range
MODE Pin Discontinuous Conduction Mode (DCM)
Range
MODE Pin Burst Mode Operation Threshold
DIR Pin Forward Operation Threshold
DIR Pin Reverse Operation Threshold
RVSOFF
Output Voltage Low
RVSOFF
Falling Threshold Voltage
RVSOFF
Threshold Voltage Hysteresis
Soft-Start Charging Current
ICN Rising Threshold for FDCM Operation
ICN Falling Threshold for CCM Operation
IMON_INP Rising Threshold for RDCM Operation
IMON_INP Falling Threshold for CCM Operation
Regulation Voltage for FBOUT
Regulation Voltage for FBIN
Line Regulation for FBOUT and FBIN Error Amp
Reference Voltage
FBOUT Pin Bias Current
FBOUT Error Amp EA4 g
m
FBOUT Error Amp EA4 Voltage Gain
VOUTLOMON Voltage Activation Threshold
VOUTLOMON Threshold Voltage Hysteresis
VOUTLOMON Pin Bias Current
FBIN Pin Bias Current
FBIN Error Amp EA3 g
m
FBIN Error Amp EA3 Voltage Gain
VINHIMON Voltage Activation Threshold
VINHIMON Threshold Voltage Hysteresis
VINHIMON Pin Bias Current
V
VINHIMON
= 1.17V, Current Out of Pin
V
VINHIMON
= 1.24V, Current Out of Pin
V
C
= 1.2V
V
C
=1.2V
l
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).
CONDITIONS
SHDN
= 3V
l
l
l
l
l
l
l
MIN
0.75
0.4
0.8
1.6
TYP
0.8
MAX
UNITS
V
V
1.2
2.0
2.4
V
V
V
V
V
V
V
mV
μA
mV
mV
mV
mV
V
V
%/V
nA
μmho
V/V
1.6
1.2
0.08
1.155
13
1.209
165
19
255
205
255
205
1.207
1.205
0.002
15
345
245
0.5
1.275
25
280
235
280
235
1.222
1.226
0.005
I
RVSOFF
= 200μA
l
l
V
SS
= 0V
MODE = 1V (HCM), DIR = 3.3V
MODE = 1V (HCM), DIR = 3.3V
MODE = 1V (HCM), DIR = 0V
MODE = 1V (HCM), DIR = 0V
Regulate V
C
to 1.2V
Regulate V
C
to 1.2V
V
INCHIP
= 12V to 80V. Not Switching
Current Out of Pin
l
l
l
l
235
185
235
185
1.193
1.184
Voltage Regulation Loops (Refer to Block Diagram to Locate Amplifiers)
l
l
Falling
V
VOUTLOMON
=1.24V, Current Into Pin
V
VOUTLOMON
=1.17V, Current Into Pin
Current Out of Pin
l
1.185
1.207
24
0.01
1
10
235
150
1.225
V
mV
μA
μA
nA
μmho
V/V
l
0.8
1.2
Rising
l
1.185
1.207
24
0.03
1
1.209
1.21
1.23
V
mV
μA
μA
V
V
0.8
1.185
1.185
1.2
1.231
1.24
Current Regulation Loops (Refer to Block Diagram to Locate Amplifiers)
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