LTC3863
60V Low I
Q
Inverting
DC/DC Controller
FEATURES
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DESCRIPTION
The
LTC
®
3863
is a robust, inverting DC/DC PMOS control-
ler optimized for automotive and industrial applications. It
drives a P-channel power MOSFET to generate a negative
output and requires just a single inductor to complete the
circuit. Output voltages from –0.4V to –150V are typically
achievable with higher voltages possible, only limited by
external components.
The LTC3863 offers excellent light load efficiency, draw-
ing only 70μA quiescent current in a user programmable
Burst Mode operation. Its peak current mode, constant
frequency PWM architecture provides for good control of
switching frequency and output current limit. The switch-
ing frequency can be programmed from 50kHz to 850kHz
with an external resistor and can be synchronized to an
external clock from 75kHz to 750kHz.
The LTC3863 offers programmable soft-start or output
tracking. Safety features include overvoltage, overcurrent
and short-circuit protection including frequency foldback.
The LTC3863 is available in thermally enhanced 12-lead
MSOP and 3mm
×
4mm DFN packages.
L,
LT, LTC, LTM, OPTI-LOOP Linear Technology, Burst Mode and the Linear logo are registered
,
trademarks and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks
are the property of their respective owners. Protected by U.S. Patents including 5731694.
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Wide Operating V
IN
Range: 3.5V to 60V
Wide Negative V
OUT
Range: –0.4V to Beyond –150V
Low Operating I
Q
= 70µA
Strong High Voltage MOSFET Gate Driver
Constant Frequency Current Mode Architecture
Verified FMEA for Adjacent Pin Open/Short
Selectable High Efficiency Burst Mode
®
Operation or
Pulse-Skipping Mode at Light Loads
Programmable Fixed Frequency: 50kHz to 850kHz
Phase-Lockable Frequency: 75kHz to 750kHz
Accurate Current Limit
Programmable Soft-Start or Voltage Tracking
Internal Soft-Start Guarantees Smooth Start-Up
Low Shutdown I
Q
= 7µA
Available in Small 12-Lead Thermally Enhanced
MSOP and DFN Packages
APPLICATIONS
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Industrial and Automotive Power Supplies
Telecom Power Supplies
Distributed Power Systems
TYPICAL APPLICATION
4.5V to 16V Input, –5V/1.7A Output, 350kHz Inverting Converter
0.47µF
350kHz
RUN
CAP
V
IN
16m
SENSE
GATE
ITH
FREQ
SGND
V
FBN
PGND
V
FB
68pF
80.6k
3863 TA01a
Efficiency
90
V
IN
= 12V
80 V
OUT
= –5V
70
EFFICIENCY (%)
60
50
40
30
20
10
0
0.002
POWER LOSS
0.02
0.2
LOAD CURRENT (A)
2
3863 TA01b
10µF
+
25V
×2
100µF
20V
V
IN
4.5V TO 16V
9
8
7
PLLIN/MODE
SS
27nF
14.7k
61.9k
EFFICIENCY
POWER LOSS (W)
6
5
PULSE-SKIPPING MODE
Burst Mode OPERATION
4
3
2
1
0
Si7129
B540C
511k
33µF
×2
LTC3863
10µH
V
OUT
–5V
150µF 1.7A
16V
×2
For more information
www.linear.com/3863
+
3863f
1
LTC3863
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Supply Voltage (V
IN
) ......................... –0.3V to 65V
V
IN
-V
SENSE
Voltage ...................................... –0.3V to 6V
V
IN
-V
CAP
Voltage ........................................ –0.3V to 10V
RUN Voltage............................................... –0.3V to 65V
V
FBN
, PLLIN/MODE Voltages ....................... –0.3V to 6V
SS, ITH, FREQ, V
FB
Voltages ........................ –0.3V to 5V
Operating Junction Temperature Range (Notes 2, 3, 4)
LTC3863E,I ....................................... –40°C to 125°C
LTC3863H .......................................... –40°C to 150°C
LTC3863MP ....................................... –55°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
MSOP Package ................................................. 300°C
PIN CONFIGURATION
TOP VIEW
PLLIN/MODE
FREQ
SGND
SS
V
FB
ITH
1
2
3
4
5
6
13
PGND
12 GATE
11 V
IN
10 SENSE
9
8
7
CAP
RUN
V
FBN
PLLIN/MODE
FREQ
SGND
SS
V
FB
ITH
1
2
3
4
5
6
TOP VIEW
12
11
10
9
8
7
GATE
V
IN
SENSE
CAP
RUN
V
FBN
13
PGND
DE PACKAGE
12-LEAD (4mm
×
3mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 43°C/W,
θ
JC
= 5.5°C/W
EXPOSED PAD (PIN 13) IS PGND, MUST BE SOLDERED TO PCB
MSE PACKAGE
12-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 40°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 13) IS PGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3863EMSE#PBF
LTC3863IMSE#PBF
LTC3863HMSE#PBF
LTC3863MPMSE#PBF
LTC3863EDE#PBF
LTC3863IDE#PBF
LTC3863HDE#PBF
LTC3863MPDE#PBF
TAPE AND REEL
LTC3863EMSE#TRPBF
LTC3863IMSE#TRPBF
LTC3863HMSE#TRPBF
LTC3863MPMSE#TRPBF
LTC3863EDE#TRPBF
LTC3863IDE#TRPBF
LTC3863HDE#TRPBF
LTC3863MPDE#TRPBF
PART MARKING*
3863
3863
3863
3863
3863
3863
3863
3863
PACKAGE DESCRIPTION
12-Lead Plastic MSOP
12-Lead Plastic MSOP
12-Lead Plastic MSOP
12-Lead Plastic MSOP
12-Lead (4mm × 3mm) Plastic DFN
12-Lead (4mm × 3mm) Plastic DFN
12-Lead (4mm × 3mm) Plastic DFN
12-Lead (4mm × 3mm) Plastic DFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–55°C to 150°C
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–55°C to 150°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping
container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
3863f
2
For more information
www.linear.com/3863
LTC3863
ELECTRICAL CHARACTERISTICS
SYMBOL
Input Supply
V
IN
V
UVLO
I
Q
Input Voltage Operating Range
Undervoltage Lockout
(V
IN
-V
CAP
) Ramping Up Threshold
(V
IN
-V
CAP
) Ramping Down Threshold
Hysteresis
PLLIN/MODE = 0V, FREQ = 0V,
V
FB
= 0.83V (No Load)
PLLIN/MODE = Open, FREQ = 0V,
V
FB
= 0.83V (No Load)
RUN = 0V
l
l
l
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, unless otherwise noted. (Note 4)
PARAMETER
CONDITIONS
MIN
3.5
3.25
3.00
3.50
3.25
0.25
0.77
50
7
0.791
–0.005
–0.1
–0.015
1.8
–50
V
FB
= 0.77V
V
SENSE
= V
IN
V
RUN
Rising
V
SS
= 0V
R
FREQ
= 24.9kΩ
R
FREQ
= 64.9kΩ
R
FREQ
= 105kΩ
FREQ = 0V
FREQ = Open
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TYP
MAX
60
3.8
3.50
UNITS
V
V
V
V
mA
µA
µA
V
%/V
%
mS
Input DC Supply Current
Pulse-Skipping Mode
Burst Mode Operation
Shutdown Supply Current
1.2
70
12
0.809
0.005
0.1
Output Sensing
V
REG
∆V
REG
∆V
IN
∆V
REG
∆V
ITH
g
m(EA)
I
FBN
V
ILIM
I
SENSE
V
RUN
V
RUNHYS
I
SS
f
Regulated Feedback Voltage V
REG
= (V
FB
– V
FBN
) V
ITH
= 1.2V (Note 5)
Feedback Voltage Line Regulation
Feedback Voltage Load Regulation
Error Amplifier Transconductance
Feedback Negative Input Bias Current
Current Limit Threshold (V
IN
-V
SENSE
)
SENSE Pin Input Current
RUN Pin Enable Threshold
RUN Pin Hysteresis
Soft-Start Pin Charging Current
Programmable Switching Frequency
V
IN
= 3.8V to 60V (Note 5)
V
ITH
= 0.6V to 1.8V (Note 5)
V
ITH
= 1.2V, ∆I
ITH
= ±5µA (Note 5)
0.800
–10
95
0.1
50
103
2
1.32
nA
mV
µA
V
mV
µA
kHz
kHz
kHz
kHz
kHz
kHz
V
V
%
ns
Current Sensing
85
Start-Up and Shutdown
1.22
1.26
150
10
105
440
810
350
535
Switching Frequency and Clock Synchronization
375
320
485
75
2
0.5
18
220
505
380
585
750
f
LO
f
HI
f
SYNC
V
CLK(IH)
V
CLK(LO)
f
FOLD
t
ON(MIN)
Low Switching Frequency
High Switching Frequency
Synchronization Frequency
Clock Input High Level into PLLIN/MODE
Clock Input Low Level into PLLIN/MODE
Foldback Frequency as Percentage of
Programmable Frequency
Minimum On-Time
V
FB
= 0V, V
FREQ
= 0V
3863f
For more information
www.linear.com/3863
3
LTC3863
ELECTRICAL CHARACTERISTICS
SYMBOL
Gate Driver
V
CAP
V
CAPDROP
Gate Bias LDO Output Voltage (V
IN
-V
CAP
)
Gate Bias LDO Dropout Voltage
I
GATE
= 0mA
V
IN
= 5V, I
GATE
= 15mA
9V ≤ V
IN
≤ 60V, I
GATE
= 0mA
Load = 0mA to 20mA
Gate High
Gate Low
GATE Going High without Delay,
V
FB(OV)
-V
FB(NOM)
in Percent
–3.5
2
0.9
10
l
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, unless otherwise noted. (Note 4)
PARAMETER
CONDITIONS
MIN
7.6
TYP
8.0
0.2
0.002
MAX
8.5
0.5
0.03
UNITS
V
V
%/V
%
Ω
Ω
%
∆V
CAP(LINE)
Gate Bias LDO Line Regulation
∆V
CAP(LOAD)
Gate Bias LDO Load Regulation
R
UP
R
DN
Overvoltage
V
FBOV
V
FB
Overvoltage Lockout Threshold
Gate Pull-Up Resistance
Gate Pull-Down Resistance
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Continuous operation above the specified maximum operating
junction temperature may impair device reliability or permanently damage
the device.
Note 3:
The junction temperature (T
J
in °C) is calculated from the ambient
temperature (T
A
in °C) and power dissipation (P
D
in Watts) as follows:
T
J
= T
A
+ (P
D
•
θ
JA
)
where
θ
JA
(in °C/W) is the package thermal impedance provided in the Pin
Configuration section for the corresponding package.
Note 4:
The LTC3863 is tested under pulsed load conditions such that T
J
≈ T
A
. The LTC3863E is guaranteed to meet performance specifications
from 0°C to 85°C operating junction temperature range. The LTC3863E
specifications over the –40°C to 125°C operating junction temperature
range are assured by design, characterization and correlation with
statistical process controls. The LTC3863I is guaranteed to meet
performance specifications over the –40°C to 125°C operating junction
temperature range, the LTC3863H is guaranteed over the –40°C to 150°C
operating junction temperature range, and the LTC3863MP is guaranteed
and tested over the full –55°C to 150°C operating junction temperature
range. High junction temperatures degrade operating lifetimes; operating
lifetime is derated for junction temperatures greater than 125°C. The
maximum ambient temperature consistent with these specifications is
determined by specific operating conditions in conjunction with board
layout, the rated package thermal impedance and other environmental
factors.
Note 5:
The LTC3863 is tested in a feedback loop that adjust V
REG
or (V
FB
– V
FBN
) to achieve a specified error amplifier output voltage
(on ITH pin).
3863f
4
For more information
www.linear.com/3863
LTC3863
TYPICAL PERFORMANCE CHARACTERISTICS
Pulse-Skipping Mode Operation
Waveforms
V
OUT
50mV/DIV
V
SW
10V/DIV
I
L
500mA/DIV
2µs/DIV
V
IN
= 12V
V
OUT
= –5V
I
LOAD
= 100mA
FIGURE 7 CIRCUIT
3863 G01
T
A
= 25°C, unless otherwise noted.
Transient Response:
Burst Mode Operation
I
LOAD
1A/DIV
V
OUT
200mV/DIV
I
L
1A/DIV
Burst Mode Operation
Waveforms
V
OUT
50mV/DIV
V
SW
10V/DIV
I
L
500mA/DIV
20µs/DIV
V
IN
= 12V
V
OUT
= –5V
I
LOAD
= 100mA
FIGURE 7 CIRCUIT
3863 G02
100µs/DIV
V
IN
= 12V
V
OUT
= –5V
TRANSIENT = 100mA TO 1.6A
FIGURE 7 CIRCUIT
3863 G03
Transient Response:
Pulse-Skipping Mode Operation
I
LOAD
1A/DIV
V
OUT
200mV/DIV
I
L
1A/DIV
100µs/DIV
V
IN
= 12V
V
OUT
= –5V
TRANSIENT = 100mA TO 1.6A
FIGURE 7 CIRCUIT
3863 G04
Transient Response: Rising Edge
Pulse-Skipping Mode Operation
I
LOAD
1A/DIV
V
OUT
200mV/DIV
I
L
1A/DIV
10µs/DIV
V
IN
= 12V
V
OUT
= –5V
TRANSIENT = 100mA TO 1.6A
FIGURE 7 CIRCUIT
3863 G05
Transient Response: Falling Edge
Pulse-Skipping Mode Operation
I
LOAD
1A/DIV
V
OUT
200mV/DIV
I
L
1A/DIV
10µs/DIV
V
IN
= 12V
V
OUT
= –5V
TRANSIENT = 1.6A TO 100mA
FIGURE 7 CIRCUIT
3863 G06
Normal Soft-Start
V
IN
5V/DIV
V
OUT1
2V/DIV
V
OUT2
2V/DIV
TRACK/SS
200mV/DIV
1ms/DIV
V
IN
= 12V
V
OUT1
= 5V
V
OUT2
= –5V
I
LOAD1
= I
LOAD2
= 100mA
FIGURE 11 CIRCUIT
3863 G07
Soft-Start into a Prebiased
Output
RUN
5V/DIV
V
OUT1
2V/DIV
V
OUT2
2V/DIV
TRACK/SS
200mV/DIV
1ms/DIV
V
IN
= 12V
V
OUT1
= 5V, V
OUT2
= –5V
PRE-BIAS1 = 2V, PRE-BIAS2 = –2V
I
LOAD
= 50mA
FIGURE 11 CIRCUIT
3863 G08
Output Tracking
V
OUT2
2V/DIV
TRACK/SS
200mV/DIV
V
OUT1
2V/DIV
20ms/DIV
V
IN
= 12V
V
OUT1
= 5V
V
OUT2
= –5V
I
LOAD1
= I
LOAD2
= 100mA
FIGURE 11 CIRCUIT
3863 G09
3863f
For more information
www.linear.com/3863
5
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