LTC3863 Datasheet, PDF (1/36 Pages) Linear Technology – 60V Low IQ Inverting DC/DC Controller Wide Operating VIN Range: 3.5V to 60V

LTC3863
60V Low I_Q Inverting
DC/DC Controller
FEATURES
n _{Wide Operating VIN Range: 3.5V to 60V}
n _{Wide Negative VOUT Range: –0.4V to Beyond –150V}
n _{Low Operating IQ = 70µA}
n _{Strong High Voltage MOSFET Gate Driver}
n _{Constant Frequency Current Mode Architecture}
n _{Verified FMEA for Adjacent Pin Open/Short}
n _{Selectable High Efficiency Burst Mode}^® _{Operation or}
Pulse-Skipping Mode at Light Loads
n _{Programmable Fixed Frequency: 50kHz to 850kHz}
n _{Phase-Lockable Frequency: 75kHz to 750kHz}
n _{Accurate Current Limit}
n _{Programmable Soft-Start or Voltage Tracking}
n _{Internal Soft-Start Guarantees Smooth Start-Up}
n _{Low Shutdown IQ = 7µA}
n _{Available in Small 12-Lead Thermally Enhanced}
MSOP and DFN Packages
APPLICATIONS
n _{Industrial and Automotive Power Supplies}
n _{Telecom Power Supplies}
n _{Distributed Power Systems}
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.
TYPICAL APPLICATION
4.5V to 16V Input, –5V/1.7A Output, 350kHz Inverting Converter
350kHz
27nF
14.7k
61.9k
0.47µF
RUN ^CAP
V_IN
PLLIN/MODE
SS
SENSE
GATE
ITH _LTC3863
FREQ
SGND
PGND
V_FBN
V_FB
10µF +
25V
×2
16mΩ
V_IN
4.5V TO 16V
100µF
20V
Si7129
10µHB540C _511k
33µF
×2
V_OUT
–5V
150µF _1.7A
16V
×2
68pF
80.6k
3863 TA01a
Efficiency
90
9
V_IN = 12V
80 VOUT = –5V
8
70
7
60
EFFICIENCY
6
50
5
40
PULSE-SKIPPING MODE ⁴
30
Burst Mode OPERATION ₃
20
10
0
0.002
POWER LOSS
0.02
0.2
LOAD CURRENT (A)
2
1
0
2
3863 TA01b
For more information www.linear.com/3863
3863f
1