3
LTC1421/LTC1421-2.5
Note 3: After power-on reset, the V
OUTLO
and V
OUTHI
have to drop below the
V
TRIP
point before the charge pump is restarted.
Note 4: After power-on reset, the V
OUTLO
has to drop below the V
TRIP
point
before the charge pump is restarted.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are reference to ground unless otherwise
specified.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CCHI
= 12V, V
CCLO
= 5V unless otherwise noted (Note 2).
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
RAMP
RAMP Pin Output Current Charge Pump On, V
RAMP
= 0.4V ● 11 17 23 µA
I
CP
Charge Pump Output Current Charge Pump On, GATEHI = 0V –600 µA
GATELO = 0V –300 µA
∆V
GATEHI
GATEHI N-Channel Gate Drive V
GATEHI
− V
OUTHI
616V
∆V
GATELO
GATELO N-Channel Gate Drive V
GATELO
− V
OUTLO
10 16 V
V
AUXVCC
Auxiliary V
CC
Output Voltage V
CCLO
= 5V, Unloaded 4.5 V
V
IL
Input Low Voltage CON1, CON2, POR ● 0.8 V
V
IH
Input High Voltage CON1, CON2, POR ● 2V
I
IN
Input Current CON1, CON2, POR = GND ● –30 –60 –90 µA
V
OL
Output Low Voltage RESET, COMPOUT, PWRGD, DISABLE, FAULT, ● 0.4 V
I
O
= 3mA
CPON, I
O
= 3mA ● 1.45 V
V
OH
Output High Voltage DISABLE, I
O
= –3mA ● 4V
CPON, I
O
= –1mA ● 3.4 V
I
PU
Logic Output Pull-Up Current RESET, PWRGD, FAULT = GND –15 µA
AC CHARACTERISTICS
t
1
CON1 or CON2↓ to CPON↑ Figure 1, C
L
= 15pF ● 15 20 30 ms
t
2
PWRGD↑ to RESET↑ Figure 1, R
L
= 10k to V
CCLO
, C
L
= 15pF 160 200 240 ms
● 140 200 280 ms
t
3
PWRGD↑ to DISABLE↓ Figure 1, C
L
= 15pF 160 200 240 ms
● 140 200 280 ms
t
4
POR↓ to CPON↓ Figure 1, C
L
= 15pF ● 15 20 30 ms
t
5
PWRGD↓ to RESET↓ Figure 1, R
L
= 10k to V
CCLO
, C
L
= 15pF 32 µs
t
6
POR↑ to CPON↑ Figure 1, C
L
= 15pF 50 ns
t
7
CON1 or CON2↑ to CPON↓ Figure 1, C
L
= 15pF 50 ns
t
9
Short-Circuit Detect to FAULT↓ Figure 1, R
L
= 10k to V
CCLO
, C
L
= 15pF 20 µs
V
CCLO
– SETLO = 0mV to 100mV
t
10
Short-Circuit Detect to CPON↓ Figure 2, C
L
= 15pF 20 µs
V
CCLO
– SETLO = 0mV to 100mV
t
11
POR↑ to FAULT↑ Figure 2, R
L
= 10k to V
CCLO
, C
L
= 15pF 20 ns
t
CHL
Comparator High to Low COMP
–
= 1.232V, 10mV Overdrive ● 0.25 0.5 µs
R
L
= 10k to V
CCLO
, C
L
= 15pF
t
CLH
Comparator Low to High COMP
–
= 1.232V, 10mV Overdrive ● 1 1.5 µs
R
L
= 10k to V
CCLO
, C
L
= 15pF
