Automotive 12V, 24V and 42V Systems
DC/DC Conversion Solutions –
InfoCard 21
42V STEP-UP
LT1680
LT1070/71/72
LT1170/71/72
LT1080
s
s
Head Lamps
Neon Lighting
Entertainment,
Security and Critical
Control Systems
High Efficiency
24V/36V Conversion to
Low Voltage
42V STEP-DOWN
TO 3V, 5V, 12V, ETC.
LTC1149
LT1074HV/LT1076HV
LT1676/LT1776
s
Always-On
s
Tire
Systems
Monitor
s
Engine Controls
s
RF Door Locks
s
Cabin Alarm
42V LOAD
DRIVERS
LT1161
s
Heaters
Amplifiers
s
Tail Lamps
s
Actuators
s
Water Pump
s
Audio
14V STEP-UP
OR BUCK-BOOST
LT1170/1/2
LTC1624
LT1680
Loads in
12V Only System
s
LCD Backlighting
s
Constant-Voltage
14V Loads
s
GPS/GSM
s
Radio/Entertainment
s
42V
ALTERNATOR
28V OR 42V
STARTER
LARGE DC/DC
& CHARGER
28V/42V TO 14V
LT1339
14V
14V STEP-DOWN
TO 3V, 5V, ETC.
LT1676, LTC1159
LT1374/75/76
LT1533
Avoidance
Computer
s
Driveline Controls
s
Safety Net
s
Mobile Office, Etc.
s
Dashboard
s
Collision
12V STEP-UP
“JUMP CHARGING”
12V
LT1680
LT1339
PRIMARY
24V OR
36V
BATTERY
RESERVE
12V
BATTERY
14V LOAD DRIVERS
LT1161
LTC1153/4/5
& Actuators
Lamps
s
Electric Brakes
s
Active Suspension
s
Incandescent
s
Motors
Navig
ys-On
Alwa rs and e
c
to
Moni n Avoidan
io
r
powe
Collis
Micro lators
Regu
Syste
4
Batte V to 18V
ms
ry
to Co Conversio
nstan
t 12V n
ation
, LTC and LT are registered trademarks of Linear Technology Corporation.
Automobile design artwork courtesy of Ralph McBride and Western Washington
University. Used by permission.
Linear Technology Corporation • 1630 McCarthy Blvd. • Milpitas, CA 95035-7417 • (408) 432-1900 • www.linear-tech.com • Literature Only: 1-800-4-LINEAR
Automotive 12V, 24V and 42V Systems
DC/DC Conversion Solutions –
InfoCard 21
Linear Technology in 42V Automotive Power
DC/DC conversion is a specialty of Linear Technology Corporation. We offer an extensive line of innovative circuits for
automotive systems including switching regulators that operate to 60V or higher for the new 42V standard. These
integrated circuits are available tested and guaranteed for the automotive temperature range.
s
High Current 42V Step-Down (to 3V, 5V, 14V, etc.)
LT1339: High Power Synchronous DC/DC Controller – Up to 50A Output
s
s
s
Operation to 60V
Current Mode Operation
Synchronous Dual N-Channel Drive
s
s
s
Programmable Average Load Current Limiting
Programmable Fixed Frequency Synchronizable to 150kHz
Adaptive Nonoverlapping Gate Drive Prevents Shoot-Through
42V to 5V Efficiency Curve
(R
SENSE
= 0.002Ω)
R
SENSE
0.01Ω
0.005Ω
0.002Ω
R
SENSE
0.002Ω
I
LIMIT
10A
20A
50A
EFFICIENCY (%)
100
95
90
85
80
75
70
65
60
42V
IN
, 5V
OUT
at 50A High Power Buck Converter
1N914
12V
42V
ZTX649
1µF
IRFZ44
×2
+
47µF
100k
+
1500µF
63V
×4
10µH
50A
3A
×10
IRFZ44
×4
17
13
2
1µF
15k
4
3
1500pF
5
2200pF
4.7k
0.1µF
2200pF
7
10
12V
IN
RUN
5V
REF
SLOPE
CT
LT1339
I
AVG
V
C
V
REF
20
BOOST
TG
TS
BG
19
18
16
ZTX749
12V
ZTX649
3.3V
+
5V
2200µF 50A
6.3V
OS-CON
ZTX749
11
12
9
1k
R
SELECT
3k
1µF
10k
1N914
R
SELECT
18.2K
8.66K
3K
1.66k
1.25k
V
OUT
24V
12V
5V
3.3V
2.8V
55
50
0
10
30
40
20
OUTPUT CURRENT (AMPS)
50
SENSE
+
SENSE
–
FB
LT1339 • TA02
SYNC SGND PGND
1
8
15
LTC1149: High Efficiency Synchronous DC/DC Controller – 60V Operation
s
s
s
s
s
Operation to 60V, to 5A Output
Constant Off-Time Current Mode Operation, to 250kHz
High Efficiency over Wide Current Range
Automatic Burst Mode
TM
Operation
Logic-Controlled Micropower Shutdown
10V-48V to 5V/2A High Voltage Buck
Converter Measured Efficiency
100
s
s
s
Synchronous FET Switching for High Efficiency
Adaptive Nonoverlap Gate Drives
16-Pin Narrow SO Package
10V-48V to 5V/2A High Voltage Buck Converter
C1
0.1µF
3
C6
0.068µF
Z5U
5
16
10
15
R1
1k
7
6
C8
680pF
NPO
V
CC
V
CC
CAP
SD1
SD2
I
TH
2
V
IN
P
GATE
P
DRIVE
SENSE +
LTC1149-5
SENSE –
8
1
C3
0.047µF
Z5U
D1
1N4148
V
IN
1N4148
10V
TO 48V
C4
1µF
C5
0.1µF
+
Q1
IRFU9024
L1
62µH
C2
330µF
63V
4
9
90
V
IN
= 12V
R2
0.05Ω
5V
2A
+
EFFICIENCY (%)
80
C9
0.01µF
Q2
IRFU024
D2
MBR160
C10
220µF
×
2
10V
V
IN
= 24V
V
IN
= 48V
70
V
IN
= 36V
60
C7
3300pF
X7R
C
T
N
GATE
13
S
GND
P
GND
R
GND
11
12
14
QUIESCENT CURRENT = 1.5mA
TRANSITION CURRENT (Burst Mode
OPERATION/CONTINUOUS
OPERATION) = 570mA
D1 SILICON VBR = 75V
D2 MOTOROLA SCHOTTKY VBR = 60V
R2 KRL NP-1A-C1-0R050J Pd = 1W
L1 COILTRONICS CTX62-2-MP DCR = 0.040Ω MPP CORE
ALL OTHER CAPACITORS ARE CERAMIC
C2
50
0.001
0.01
0.1
OUTPUT CURRENT (A)
1
2
C4
C10
Q1
Q2
UNITED CHEMI-CON (Al) LXF63VB331M12.5 x 30
ESR = 0.170
Ω
I
RMS
= 1.280A
(Ta)
SANYO (OS-CON) 10SA22OM ESR = 0.035Ω I
RMS
= 2.360A
IR PMOS BV
DSS
= 60V RDS
ON
= 0.280Ω C
RSS
= 65pF Q
g
= 19nC
IR NMOS BV
DSS
= 60V RDS
ON
= 0.100Ω C
RSS
= 79pF Q
g
= 28nC
Burst Mode is a trademark of Linear Technology Corporation.
2
Automotive 12V, 24V and 42V Systems
DC/DC Conversion Solutions –
InfoCard 21
s
PolyPhase
TM
Regulators for Improved Performance
For high current step-down applications, two out-of-phase IC controllers provide significant improvements* and
reduced component cost that offset the cost of the second controller IC. Major benefits include:
s
s
s
Two Output Inductors 1/8 the Size of a Single Inductor
(Total 1/4 the Magnetics)
Significantly Reduced Output Ripple
Significantly Reduced Input Capacitor Ripple Current
Allows the use of Fewer Input Capacitors
s
s
Greatly Improved Transient Response—Two Smaller
Inductors: Slew Currents Are Additive
Minimizes the Size of MOSFETs, May Save the Need to
Parallel MOSFETs
Design Approach for Very Low Ripple/Noise and Improved Transient Response
C1
0.1µF
5
4
6
8
12
3
14
10
AST V
CC
Q
AST
Q 11
U1
–T
+T CD4047
13
RET
OSC
RCC
SYNC1
SYNC2
NC
R1
10k
Q7
MJD112
D2
MMSZ4699T1
12V
12V BIAS
D1
BAT54
C3
150µF
16V
SANYO
SYNC1
OS-CON-SP
17
1
12V
IN
SYNC
BOOST
TG
20
19
C7, 0.22µF
R5
191k
1%
2
5V
REF
4
SL/SDJ
3
5
6
7
10
C
T
I
AVG
SS
V
C
V
REF
SGND
8
C13
1000pF
TS
11
S
+
–
12
S
16
BG
14
R7
NC 10k
PHASE
13
RUN/SD
9
V
FB
15
FEEDBACK
V
IN
42V
12V BIAS
C19
0.22µF
25V
18
D3
BAT54
Q2
IRFZ34S
C6
0.1µF
50V
12V
V
IN
42V
C5
1500µF
50V
SANYO
MV-GX
R2
16.5k
C2
100pF 1
CX
2
RX
9
RST
C4
0.1µF
25V
+
+
OUTPUT
12V
15A
GND
7
f
OSC
= 200kHz
U2
LT1339
L1
15µH
Q4
IRFZ44S
D4
MBRS340L
R4
0.010Ω
1%
+
SS
V
C
R8
4.3k
C16
6800pF
C12
2000pF
C8
+
150µF
16V
SANYO
OS-CON-SA
C33
1300pF
50V
R21
16k
C9
150µF
16V
SANYO
OS-CON-SA
C14
1000pF
PGND
C10
1000pF
C15
1000pF
C11
0.1µF
R12
10.7k
1%
R13
1.24k
1%
+
SYNC2
1
SYNC
17
12V
IN
BOOST
TG
20
19
D6
BAT54
Q5
IRFZ34S
C21
0.1µF
50V
+
C20
1500µF
50V
SANYO
MV-GX
C22, 0.22µF
R16
191k
1%
2
5V
REF
4
SL/SDJ
3
5
6
7
10
C
T
I
AVG
SS
V
C
V
REF
SGND
8
18
TS
S
+
11
12
S
–
16
BG
14
PHASE
13
RUN/SD
9
V
FB
15
U4
LT1339
L2
15µH
Q6
IRFZ44S
NC
RUN
FEEDBACK
D7
MBRS340L
R15
0.010Ω
1%
+
C29
0.1µF
C28
1000pF
C30
1000pF
SS
V
C
C24
+
150µF
16V
SANYO
OS-CON-SA
C25
150µF
16V
SANYO
OS-CON-SA
C31
1000pF
PGND
IC21/1339
PolyPhase is a trademark of Linear Technology Corporation.
*See
Linear Technology
magazine, November 1998, p.27
s
Selection Guide for 42V Automotive DC/DC Conversion
Regulator
V
IN
I
OUT
Synch
Circuit
Range
Range
Drive*
60V Input Step-Down Switching Regulators
LT1676
7.4V to 60V
10mA to 500mA
LT1776
7.4V to 60V
10mA to 500mA
LT1076HV
8V to 64V
to 2A
LT1074HV
8V to 64V
to 5A
LTC1149
4V to 60V
to 5A
Yes
LT1339
10V to 60V
1A to 50A
Yes
42V Output Step-Up (or SEPIC) Switching Regulators
LT1680
10V to 60V
1A to 50A
LT1339
10V to 60V
1A to 50A
Yes
LTC1624
3.5V to 36V
10A
Burst
Mode
X**
X**
I
Q
Shutdown
Supply Current Package
3.2mA
†
3.2mA
†
8.5mA
8.5mA
2mA
14mA
††
12mA
16mA
††
550µA
30µA
30µA
140µA
140µA
135µA
65µA
65µA
65µA
16µA
S8
S8
K,T,R
K,T,T7
S16
N20, SW20
N16, SW16
N20, SW20
S8
Features
No Pulse Skipping at Light Load, 100kHz
No Pulse Skipping at Light Load, 200kHz
Onboard Switches
Low Quiescent Current
High Efficiency over Wide Range
High Current N-Channel Drive
To 10,000pF Gate Capacitance
Adaptive Gate Drive
Optimum Load Step Response
X
X
* Synchronous 2-switch transistor drive for maximum efficiency
** External comparator required
†
Plus minimum V load of a few mA
††
Plus FET charge currents
CC
Package Codes: K = TO-3, N = Plastic Power DIP, R = 7-Lead DD, S = Narrow Small Outline, SW = Wide SO (0.300
"
), T = TO-220,
3
Automotive 12V, 24V and 42V Systems
DC/DC Conversion Solutions –
InfoCard 21
s
42V Step-Down (Integrated Switch)
LT1074 Series: High Voltage, High Efficiency Switching Voltage Regulators
s
s
s
s
Input Voltage Range to 60V or 75V
1A, 2A and 5A Onboard Switches (see Table, p.6)
Current Mode Operation, May Be Synchronized to
External Clock
Few External Components
Basic Positive Buck Converter
L1**
50µH (LT1074)
100µH (LT1076)
V
IN
V
SW
LT1074HV
GND
V
C
FB
R3
2.7k
C2
0.01µF
MBR745*
R1
2.8k
1%
R2
2.21k
1%
+
s
s
s
s
Low Quiescent Current: < 10mA
Micropower Shutdown Mode
Pulse-by-Pulse Programmable Current Limiting
Low Thermal Resistance Packages
Buck Converter Efficiency
LT1074
10V
TO 60V
+
C3
†
200µF
* USE MBR340 FOR LT1076
** COILTRONICS
#50-2-52 (LT1074)
#100-1-52 (LT1076)
PULSE ENGINEERING, INC.
#PE-92114 (LT1074)
#PE-92102 (LT1076)
HURRICANE
#HL-AK147QQ (LT1074)
C1
#HL-AG210LL (LT1076)
500µF
†
RIPPLE CURRENT RATING
≥
I /2
OUT
25V
5V
5A
100
EFFICIENCY (%)
90
80
V
OUT
= 12V, V
IN
= 20V
V
OUT
= 5V, V
IN
= 15V
70
60
50
0
1
2
3
4
5
6
OUTPUT LOAD CURRENT (A)
L = 50µH TYPE 52 CORE
DIODE = MBR735
LT1676/LT1776: High Efficiency Step-Down Switching Regulators
s
s
s
s
Wide Input Range: 7.4V to 60V*
True Current Mode Control
700mA Peak Switch Current
Adaptive Switch Drive Prevents Pulse Skipping at Light Loads
s
s
s
s
Fixed Frequency LT1676: 100kHz, LT1776: 200kHz
LT1676 Is Synchronizable to 250kHz (LT1776 to 400kHz)
Micropower Shutdown Mode
8-Pin SO and Power DIP Packages
Efficiency vs V
IN
and I
LOAD
V
IN
7.4V TO 60V
1
90
5
V
IN
SHDN
V
CC
V
SW
39µF
63V
6
LT1676
7
FB
8
V
C
2200pF
22k
100pF
12.1k
1%
30
20
1
2
EFFICIENCY (%)
80
3
220µH*
+
+
MBR160
5V
400mA
100µF
10V
36.5k
1%
70
60
50
40 V
IN
= 12V
V
IN
= 24V
V
IN
= 36V
V
IN
= 48V
10
I
LOAD
(mA)
1676 TA01
SYNC
GND
4
100
1000
*65T #30 ON MAGNETICS
MPP #55030
1676 F01
* The LT1776 is limited to 40V continuous DC input due to thermal constraints, but can withstand transients up to 60V.
4
Automotive 12V, 24V and 42V Systems
DC/DC Conversion Solutions –
InfoCard 21
s
High Current 14V to 42V Step-Up DC/DC Conversion
For charging 36V batteries or powering 42V equipment from a 12V source
LT1680: High Power DC/DC Step-Up Controller
s
s
s
s
s
Operation to 60V
All N-Channel Drive Handles up to 10,000pF Gate Capacitance
High Power Output to 250W or More
Fixed Frequency Current Mode Operation
Synchronizable to 200kHz
Efficiency vs Output Power
100
V
OUT
= 48V
C
CT
1nF
s
s
s
s
Programmable Average Current Limiting
Undervoltage Lockout with Hysteresis
User-Adjustable Slope Compensation
16-Pin SO and DIP Packages
12V to 42V, 250W Boost
C2
1µF
R
CT
15k
LT1680
1
2
SL/ADJ
C
T
I
AVG
SS
V
C
5V
REF
SYNC
12V
IN
GATE
PGND
SENSE
–
SENSE
+
16
15
14
13
12
11
10
9
12V
IN
10V TO 15V
24A (DC) R
SENSE
0.005Ω
+
+
95
EFFICIENCY (%)
C
IN
680µF
25V
×4
C12
1µF
L1
25µH
90
C3, 2.2nF
C4, 0.22µF
C
VC
, 4.7nF
1N914
3
4
5
6
7
8
85
M1
IRFZ44
×
3
R
VC
, 4.7k
SGND RUN/SHDN
V
FB
V
REF
R9
100k
MBR0520
C11, 1nF
D1
MBR20100CT
×
2
80
C6, 0.1µF
R7
2k
75
R6
64.9k
0
50
150
200
100
OUTPUT POWER (W)
250
1680 TA02
+
L1: Kool Mµ , 18T #14 ON 77314-A7
Kool Mµ IS A REGISTERED TRADEMARK OF MAGNETICS, INC.
®
C
OUT
680µF
63V
1680 TA01
×3
V
OUT
42V
6A
The LT1339 will also provide 42V output, high current synchronous boost conversion (see data sheet).
Automotive Power Circuits
Battery Charger Circuits (For In-Vehicle Cell Phones, PCs, etc.)
Power
Circuit
LT1505
LT1510
LT1511
LT1512
LT1513
LT1620/1
V
IN
Range
*
3V to 27V
8V to 30V
8V to 30V
3V to 30V**
3V to 30V**
to 32V
I
OUT
Max
>5A
1.5A
3A
1A
2A
>10A
Step-Up/
Down
Batteries
Charged
NiCd,NiMH,Li-Ion,SLA
NiCd,NiMH,Li-Ion
NiCd,NiMH,Li-Ion
NiCd,NiMH,Li-Ion,SLA
NiCd,NiMH,Li-Ion,SLA
NiCd,NiMH,Li-Ion,SLA
** 40V max for on-chip switch
I
Q
Shutdown
Supply Current
12mA
2.9mA
4.5mA
4mA
4mA
2.8mA
5µA
3µA
3µA
12µA
12µA
†
LT1512
Packages
G24
S8,N16,GN16
SW24
N8,S8
T,R
MS8,S8,GN
Description or Features
Programmable or Preset Outputs; Constant I & V
200kHz or 500kHz Switching; Precision Reference
With Input Current Limiting; Undervoltage Lockout
Step-Up/Step-Down; 500kHz; Constant I/Constant V
Any Number of Cells to 20V
†
; Programmable Current
Current Sense Amp Used with PWM Controller IC
X
X
* Depending on battery types and quantity
to 30V
Power Driver Circuits
Power
Circuit
LTC1153
LTC1154
LTC1155
LT1161
LT1188
LTC1255
V
IN
Range
4.5V to 22V
4.5V to 22V
4.5V to 22V
8V TO 48V
5V to 30V
9V to 24V
I
OUT
Max
>20A
2.7A
5A
to 5A
1.5A
1A
Number Transient Reverse
Drivers Protection Polarity
Single
Single
Dual
Quad
Single
Dual
40V*
40V*
40V*
60V
60V
40V*
15V
15V
15V*
15V
15V
I
Q
Supply
85µA
85µA
85µA
4.5mA
5mA
0.5mA
Shutdown
Current
8µA
8µA
8µA
Packages
N8,S8
N8,S8
N8,S8
N20,S20
K,T
N8,S8
Description or Features
Autoreset Electronic Circuit Breaker
High Side MOSFET Driver
Micropower MOSFET Driver; Overcurrent Sense
External MOSFETs; –15V to 60V Transients
On-Chip Switch; Status Output
External MOSFETs; Overvoltage Protection
Fully Enhanced MOSFET Drivers
High Voltage Switch Drivers
500µA
12µA
* With external diode
Package Codes: G = SSOP (0.209" Wide), GN = Narrow SSOP (0.150"), GW = Wide SSOP (0.300"), M = 3-Lead DD, MS8 = 8-Lead MSOP,
N = Plastic DIP, Q = 5-Lead DD, R = 7-Lead DD, S = Narrow Small Outline (SO), ST = SOT-223, T = Plastic TO-220
5
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