Datasheet

LTC4365
16
Rev. B
For more information www.analog.com
REGULATOR APPLICATIONS
Hysteretic Regulator
Built-in hysteresis and the availability of both inverting
and noninverting control inputs (OV and UV) facilitate the
design of hysteretic regulators. Figure 17 shows how the
LTC4365-1 can protect a load from OV transients, while
regulating the output voltage at a user-defined level. When
the output voltage reaches its OV limit, the LTC4365-1
turns off the external MOSFETs. The load current then
discharges the output capacitance until OV falls below the
hysteresis voltage. The external MOSFETs are turned back
on after a 1ms delay. Figure 18 shows the waveforms for
the circuit of Figure 17. Note that the duration, magnitude
and duty cycle of the V
IN
glitch must not exceed the SOA
rating of the external MOSFETs.
Solar Charger
Figure 19 shows a series regulator for a solar charger.
The LTC4365-1 connects the solar charger to the battery
when the battery voltage falls below 13.9V (after a 1ms
delay). Conversely, when the battery reaches 14.6V, the
LTC4365-1 immediately (2µs) opens the charging path.
Regulation of the battery voltage is achieved by connect-
ing a
resistive divider from the battery to the accurate OV
comparator input (with 5% hysteresis). The fast rising
response of the OV comparator prevents the battery voltage
from rising above the user-selected threshold.
APPLICATIONS INFORMATION
Figure 17. Hysteretic Regulation of V
OUT
During OV Transients Figure 18. V
OUT
Regulates at 16V When V
IN
Glitches Above Desired Level
V
IN
UV
OV
SHDN
4365 F17
V
OUT
FAULT
GATE
V
IN
12V
Si4946
DUAL NCH
OPTIONAL
SNUBBER
V
OUT
GND
LTC4365-1
R5
510k
C
LOAD
47µF
C
OV
220pF
+
R
LOAD
100Ω
R2
1820k
R1
59k
1µF
R7
1Ω
4365 F18
2.5ms/DIV
5V/DIV
GND
V
OUT
V
IN
V
IN
4365 F19
V
OUT
GATEUVSHDN
1/2 OF Si4214 1/2 OF Si4214
GND
LTC4365-1
OV
M1
D1
D4
B130
D2
M2
+
TO LOAD
C
BATT
100µF
C
BYP
100nF
15W
SOLAR
PANEL
R2
3.24M
R1
115k
14.6V OFF
13.9V ON
C
OV
220pF
12V, 8Ah
GELCELL
Figure 19. Series Hysteretic Solar Charger with Reverse-Battery and Solar Panel Protection
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