LTC2907 LINER [Linear Technology], LTC2907 Datasheet - Page 12

• Manufacturer Part Number: LTC2907
• Description: 36V Nano-Current Two Input Voltage Monitor
• Manufacturer: LINER [Linear Technology]

LTC2960
APPLICATIONS INFORMATION
When a supply voltage is abruptly connected to the input
resonant ringing can occur as a result of series inductance.
The peak voltage could rise to 2x the input supply but in
practice can reach 2.5x if a capacitor with a strong volt-
age coefficient is present. If a 12V supply is hot plugged
the resulting ringing could reach the abs max of V
circuit with an input of more than 7V should be scrutinized
for ringing. Circuit board trace inductances of as little as
10nH can produce significant ringing.
One effective means to eliminate ringing is to include a
10–100Ω resistance in series with the supply input before
the V
ing for the resonant circuit but imposes a time constant to
V
TYPICAL APPLICATIONS
Configurable Regulator UVLO and Low Battery
Indicator
In the circuit of Figure 8, the high voltage open drain
OUT output is used as a configurable UVLO signal for a
switching regulator. A Li-Ion battery can contain protec-
tion circuitry that open circuits its terminals through an
12
CC
. In Figure 7(b), the time constant of RS and C1 is 2μs.
CC
capacitor shown in Figure 7(b). This provides damp-
Li-Ion
Li-Ion
4.2V
4.2V
UVLO FALLING THRESHOLD = 5.537V
RESET FALLING THRESHOLD = 6.33V
+
+
Figure 8. Configurable Regulator UVLO and Low Battery Indicator
C1
0.1μF
25V
R3
5.11M*
R2
49.9k
R1
348k
6V TO 8.4V
V
RT
IN
ADJ
MR
LTC2960-1
V
CC
+
BAT
GND
CC
OUT
2960 F08
RST
. Any
NOT ALL LT3991 COMPONENTS SHOWN
*VISHAY-DALE CRCW SERIES 0603 1%
R4
10M
internal switch when it reaches 2.5V. With a threshold of
5.537V the LTC2960 OUT output disables the load before
this occurs in order to prevent damage to the batteries.
In addition to the UVLO signal, the LTC2960 provides a
low battery indicator for the system. Figure 9 shows an
alternative arrangement in which the LTC2960 monitors
the output of the 3.3V regulator to provide a reset signal.
BUCK CONVERTER
V
EN
IN
LT3991
GND
Figure 7. Operation with High Voltage Transients
and Hot Swapping
V
OUT
V
IN
MAX 200V
V
IN
RZ
143k
PWC1206LF143kJ*
RS
20
Z1
BZX84C30
BV = 30V
C1
0.1μF
50V
C2
47μF
16V
V
R5
1M
CC
V
3.3V
LOW BATTERY
(a)
(b)
OUT
LTC2960
C1
0.1μF
50V
V
CC
2960 F07
*TT-IRC
LTC2960
2960f