LT8310_15 Datasheet, PDF (1/36 Pages) Linear Technology – 100VIN Forward Converter Controller

LT8310
100V_IN Forward Converter
Controller
Features
Description
n _{Input Voltage Range: 6V to 100V}
n _{Duty Mode Control Regulates an Isolated Output}
without an Opto
n _{High Efficiency Synchronous Control}
n _{Short-Circuit (Hiccup Mode) Overcurrent Protection}
n _{Programmable OVLO and UVLO with Hysteresis}
n _{Programmable Frequency (100kHz to 500kHz)}
n _{Synchronizable to an External Clock}
n _{Positive or Negative Polarity Output Voltage Feedback}
with a Single FBX Pin
n _{Programmable Soft-Start}
n _{Low Shutdown Current < 1µA}
n _{Available in FE20 TSSOP with HV Pin Spacing}
Applications
n _{Industrial, Automotive and Military Systems}
n _{48V Telecommunication Isolated Power Supplies}
n _{Isolated and Nonisolated DC/DC Converters}
The LT^®8310 is a simple-to-use resonant reset forward
converter controller that drives the gate of a low side
N-channel MOSFET from an internally regulated 10V sup-
ply. The LT8310 features duty mode control that generates
a stable, regulated, isolated output using a single power
transformer. With the addition of output voltage feedback,
via opto-coupler (isolated) or directly wired (nonisolated),
current mode regulation is activated, improving output
accuracy and load response. The flexibility to choose
transformer turns ratio makes high step-down or step-up
ratios possible without operating at duty cycle extremes.
The user can program the switching frequency from 100kHz
to 500kHz to optimize efficiency, performance or external
component size. A synchronous output is available for
controlling secondary side synchronous rectification to
improve efficiency. User programmable protection features
include monitors on input voltage (UVLO and OVLO) and
switch current (overcurrent limit). The LT8310 soft-start
feature helps protect the transformer from flux saturation.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Typical Application
78 Watt Isolated Forward Converter, ±8% V_OUT
V_IN
36V TO 72V
– V_IN
2.2µF
100V
×4 86.6k
1.74k
1.43k
UVLO V_IN
OVLO
LT8310
GATE
4.7µF
10nF
49.9k
200kHz
102k
NC
INTV_CC
RDVIN
DFILT
SYNC
RT SS
0.47µF
SENSE
GND
SOUT
V_C FBX
NC
2:1
1µF _{• •}
100V
150pF
NPO
0.025Ω
1%
NC
8310 TA01a
47µH
22µF
×8
V_OUT
12V
0.6A TO 6.5A
+
100µF
–V_OUT
For more information www.linear.com/LT8310
Output Voltage Load Regulation
14.0
13.5
13.0
12.5
12.0
11.5
11.0
V_IN = 72V
10.5
V_IN = 48V
V_IN = 36V
10.0
01 2 3 4 5 6 7
I_OUT (A)
8310 TA01b
8310f
1