LTC2928
5
2928fa
For more information www.linear.com/LTC2928
elecTrical characTerisTics
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All currents into pins are positive, all voltages are referenced to
GND unless otherwise noted.
Note 3: Internal circuits regulate the EN output voltage to V
EN
. Driving this
pin to voltages beyond V
EN
may damage the part.
Note 4: The comparator outputs have internal pull-ups to V
CC
of typically
–10µA. However, external pull-up resistors may be used when faster rise
times are required or for V
OH
voltages greater than V
CC
.
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
CC
= 3.3V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
DONE(DN)
DONE Pull-Down Current V
DONE
= 3.3V (Note 6)
l
20 40
µA
R
DONE
Required Pull-Up Resistance on “Last”
LTC2928
5% Tolerance or Better
l
2.4 5.1
kΩ
V
DONE(LAST)
Voltage Output High when Configured
as “Last”
l
0.8 • V
CC
V
Reset Pin: RST
V
RST(OL)
RST Voltage Output Low
V
CC
= 0.2V, I
RST
= 0.1µA
V
CC
= 0.5V, I
RST
= 5µA
V
CC
= 1V, I
RST
= 200µA
V
CC
= 3V, I
RST
= 2500µA
l
l
l
l
5
10
25
150
60
150
300
300
mV
mV
mV
mV
V
RST(OH)
RST Voltage Output High
I
RST
= –1µA (Note 7)
l
V
CC
– 1 V
Timer Pins: RTMR, PTMR, STMR
I
TMR(UP)
Timer Pull-Up Current V
TMR
= GND
l
–1.7 –2 –2.3
µA
I
TMR(DN)
Timer Pull-Down Current V
TMR
= 1.3V
l
15 20 25
µA
t
RTMR
t
PTMR
t
STMR
Timer Period, RTMR (Note 8)
Timer Period, PTMR
Timer Period, STMR
C
RTMR
= 1500pF
C
PTMR
= 1500pF
C
STMR
= 1500pF
l
l
l
5
5
11
6
6
13
7
7
15
ms
ms
ms
External Voltage Reference Pin: REF
V
REF
Reference Voltage Output
100% Sequence Threshold
67% Sequence Threshold
33% Sequence Threshold
10% Sequence Threshold
I
REF
= 0.2mA, –1mA, C
REF
= ≤ 1000pF
VSEL = V
CC
VSEL = V
CC
VSEL = V
CC
VSEL = V
CC
l
l
l
l
l
1.172
1.172
0.780
0.386
0.109
1.189
1.189
0.793
0.396
0.119
1.205
1.205
0.806
0.406
0.129
V
V
V
V
V
Over Voltage Indication Pin:
OV
V
OV(OL)
OV Voltage Output Low I
OV
= 2.5mA
l
0.15 0.3 V
V
OV(OH)
OV Voltage Output High (Note 7)
I
OV
= –1µA
l
V
CC
– 1 V
t
OV
OV Indication Time (Note 8) OV Low Time Upon Cleared
OV Event, C
RTMR
= 1500pF
l
5 6 7 ms
Over Voltage Adjust Pin: OVA
V
OVA(TH)
Over Voltage Threshold at Comparator
Inputs (Note 9)
V
OVA
= GND
V
OVA
Floating
V
OVA
= V
CC
= 3.3V
l
l
l
0.546
0.650
1.042
0.556
0.660
1.072
0.566
0.670
1.102
V
V
V
Note 5:
The CAS high time after an ON edge is stretched by the ON pin
propagation delay (20µs typical).
Note 6: The DONE pull-down current is present when DONE is high to
facilitate cascading multiple LTC2928s.
Note 7: The RST and OV outputs have an internal pull-up to V
CC
of
typically –10µA. However, external pull-up resistors may be used when
faster rise times are required or for V
OH
voltages greater than V
CC
.
Note 8: If the termination of under and overvoltage events occur within
one nominal t
RTMR
period, the variation in t
RTMR
and/or t
OV
may be ±15%.
Note 9: Use a resistor from OVA to ground or V
CC
to configure overvoltage
thresholds within the max/min ranges shown. See Applications
Information for details.
