LT8631 Datasheet, PDF (1/24 Pages) Linear Technology – 100V, 1A Synchronous Micropower Step-Down Regulator

Features
n _{Ultrawide Input Voltage Range: 3V to 100V}
n _{Output Voltage Range: 0.8V to 60V}
n _{Internal Synchronous Switches}
n _{Low Ripple Burst Mode}^® _Operation:
16µA I_Q at 12V_IN to 5V_OUT Output Ripple <10mV_P-P
7µA I_Q at 48V_IN to 5V_OUT Output Ripple <10mV_P-P
n _{Low Dropout: 99% Maximum Duty Cycle}
n _{Peak Current Mode Control}
n _{Fixed Frequency Operation: 100kHz to 1MHz}
n _{Synchronization Input}
n _{Programmable Undervoltage Lockout}
n _{Power Good Flag}
n _{Flexible Output Voltage Tracking}
n _{Short-Circuit Protection}
n _{Low Shutdown Current: 5µA}
n _{Tolerates Pin Open/Short Faults}
n _{Thermally Enhanced 20-Lead TSSOP with High}
Voltage Lead Spacing
Applications
n _{Automotive Supplies}
n _{Telecom Supplies}
n _{Distributed Supply Regulation}
LT8631
100V, 1A Synchronous
Micropower Step-Down
Regulator
Description
The LT^®8631 is a current mode PWM step-down DC/DC
converter with internal synchronous switches that provide
current for output loads up to 1A. The wide input range
of 3V to 100V makes the LT8631 suitable for regulating
power from a wide variety of sources, including automotive
and industrial systems and 36V to 72V telecom supplies.
Low ripple Burst Mode operation enables high efficiency
operation down to very low output currents while keeping
the output ripple below 10mV_P-P. Resistor programmable
100kHz to 1MHz frequency range and synchronization ca-
pability enable optimization between efficiency and external
component size. The soft-start feature controls the ramp
rate of the output voltage, eliminating input current surge
during start-up, while also providing output tracking. A
power good flag signals when the output voltage is within
±7.5% of the regulated output. Undervoltage lockout can
be programmed using the EN/UV pin. Shutdown mode
reduces the total quiescent current to < 5µA. The LT8631
is available in a 20-lead TSSOP package with exposed pad
for low thermal resistance and high voltage lead spacing.
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Typical Application
5V, 1A Step-Down Converter
V_IN
6.5V TO 100V
2.2µF
V_IN
BST
LT8631
EN/UV
SW
PG
0.1µF 22µH
2.2µF
25.5k
INTV_CC
IND
V_OUT
RT
FB
SYNC/MODE TR/SS
GND
4.7pF 1M
191k
0.1µF
V_OUT
5V, 1A
47µF
F_SW = 400kHz
8631 TA01a
Efficiency vs Load Current
95
F_SW = 400kHz
90
85
80
75
70
65
60
V_IN = 12V
55
V_IN = 24V
50
V_IN = 48V
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
LOAD CURRENT (A)
8631 TA01b
For more information www.linear.com/LT8631
8631f
1