Power-up/power-down characteristics – Rainbow Electronics DS1340 User Manual
Page 4
DS1340
2-Wire RTC with Trickle Charger
4
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POWER-UP/POWER-DOWN CHARACTERISTICS
(T
A
= -40°C to +85°C) (Figure 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Recovery at Power-Up
t
REC
(Note 17)
2
ms
V
CC
Fall Time; V
PF(MAX)
to
V
PF(MIN)
t
VCCF
300
µs
V
CC
Rise Time; V
PF(MIN)
to
V
PF(MAX)
t
VCCR
0
µs
WARNING: Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery-backup mode.
Note 1:
Limits at -40°C are guaranteed by design and not production tested.
Note 2:
After this period, the first clock pulse is generated.
Note 3:
A device must internally provide a hold time of at least 300ns for the SDA signal (referred to as the V
IH(MIN)
of the SCL
signal) to bridge the undefined region of the falling edge of SCL.
Note 4:
The maximum t
HD:DAT
only has to be met if the device does not stretch the low period (t
LOW
) of the SCL signal.
Note 5:
A fast-mode device can be used in a standard-mode system, but the requirement t
SU:DAT
≥ to 250ns must be met. This
is automatically the case if the device does not stretch the low period of the SCL signal. If such a device does stretch the
low period of the SCL signal, it must output the next data bit to the SDA line t
R MAX
+ t
SU:DAT
= 1000 + 250 = 1250ns
before the SCL line is released.
Note 6:
C
B
—total capacitance of one bus line in pF.
Note 7:
The parameter t
OSF
is the period of time the oscillator must be stopped for the OSF flag to be set over the 0V
≤ V
CC
≤
V
CCMAX
and 1.3V
≤ V
BAT
≤ 3.7V range.
Note 8:
All voltages are referenced to ground.
Note 9:
Measured at V
CC
= typ, V
BACKUP
= 0V, register 08h = A5h.
Note 10:
The use of the 250
Ω trickle-charge resistor is not allowed at V
CC
> 3.63V and should not be enabled.
Note 11:
Measured at V
CC
= typ, V
BACKUP
= 0V, register 08h = A6h.
Note 12:
Measured at V
CC
= typ, V
BACKUP
= 0V, register 08h = A7h.
Note 13:
I
CCA
—SCL clocking at max frequency = 400kHz.
Note 14:
Specified with 2-wire bus inactive.
Note 15:
Measured with a 32.768kHz crystal attached to the X1 and X2 pins.
Note 16:
Limits at +25°C are guaranteed by design and not production tested.
Note 17:
This delay applies only if the oscillator is enabled and running. If the oscillator is disabled or stopped, no power-up delay
occurs.
SDA
SCL
t
HD:STA
t
LOW
t
HIGH
t
R
t
F
t
BUF
t
HD:DAT
t
SU:DAT
REPEATED
START
t
SU:STA
t
HD:STA
t
SU:STO
t
SP
STOP
START
Figure 1. Data Transfer on 2-Wire Serial Bus