DS1632S Maxim Integrated Products, DS1632S Datasheet - Page 3

• Manufacturer Part Number: DS1632S
• Description: IC CTRLR PC PWR FAIL/RSET 16SOIC
• Manufacturer: Maxim Integrated Products
• Series: -r

Specifications of DS1632S

• Applications: PC Power-Fail and Reset Controller
• Voltage - Input: -
• Voltage - Supply: 4.5 V ~ 5.5 V
• Current - Supply: 500µA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.295", 7.50mm Width)
• Lead Free Status / Rohs Status: Contains lead / RoHS non-compliant

DS1632
OPERATION – POWER-FAIL, BATTERY BACKUP
The DS1632 provides a switch to direct power from the battery (V
) or the incoming supply (V
),
BAT
CC
depending on which is greater. This switch has a voltage drop of less than 0.3 volts. The V
input is
CC
constantly monitored by a precision comparator for an out-of-tolerance condition. When such a condition
occurs, the power-fail signals are driven to their active state immediately. The reset signals are also driven
active, but this action is delayed by a time determined by the level of the input on the reset duration pin
(RD). If RD is tied to ground then reset signals will become active after 9 ms. If RD is tied to V
, then
CC
reset signals will become active after 18 ms. Once active, both the reset signals and the power-fail signals
will remain active as long as a (V
) out-of-tolerance condition persists. If an out-of-tolerance condition
CC
is not long enough to activate the reset signals, then only the power-fail signals would be affected. When
power returns to within nominal limits the power-fail signals will return immediately to the inactive state.
However, the reset signals remain in the active state for a time which is dependent on the state of the RD
pin. If RD is tied to ground, the reset signals will remain active for 95 ms. If RD is tied to V
, then the
CC
reset signals will remain active for 190 ms after power is within nominal limits. The delay action on the
reset signals allows time for the power supply and microprocessor clock oscillators to stabilize. The
tolerance pin (TOL) selects the point at which power-fail detection occurs. With the tolerance pin
grounded, power-fail detection occurs in the range of 4.75V to 4.5V. If the tolerance pin is connected to
V
, then power-fail detection occurs in the range of 4.5V to 4.25V. During most power supply
CC
conditions the V
input will supply power to all functions within the chip and also to the V
pin. The
CC
CCO
battery pin (V
) only supplies power when V
is less than V
. When V
is below the level of V
BAT
CC
BAT
CC
BAT
only the V
and the OSC OUT pin remain powered by V
. All other outputs will be driven to ground
CCO
BAT
when in a logic low state and will be driven to V
when in a logic high state. This is done to preserve
CC
battery capacity by avoiding battery drain resulting from loads on these outputs. The output ground level
will be maintained for all levels of V
, even V
= GND. However, the output V
level will be
CC
CC
CC
> 2.0V. Internal battery power consumption is less than 2 mA while V
maintained only for V
is
CC
BAT
supplying power. The external load on OSC OUT and V
must be added to internal consumption to
CCO
determine the total load on the battery.
OPERATION - PUSHBUTTON RESET
The DS1632 provides an input pin for direct connection to a pushbutton. The pushbutton reset input
requires an active low level input. While TTL levels are sufficient to properly activate this input,
PBRST
it has been primarily designed for contact closure. Internally, this input is debounced and timed such that
RST and
signals of 95ms or 190 ms minimum are generated. If RD is tied to ground, then a reset
RST
pulse of 95 ms is generated. If RD is tied to V
then a reset pulse of 190 ms is generated. The delay time
CC
is started as the pushbutton reset input is released from low level.
OPERATION - LOW BATTERY WARNING
The DS1632 provides outputs which warn of a low battery condition. Whenever V
is within nominal
CC
limits, the V
input is continuously monitored. If the V
input is out of tolerance, the low battery
BAT
BAT
outputs are driven to their active states, and will remain in the active state as long as V
is within
CC
nominal limits or until the battery input is restored to an in limit status. On power-up, if the V
input is
BAT
out of tolerance, the low battery outputs are not guaranteed active until power-fail is deactivated, but
guaranteed active prior to reset inactive. When V
is below the V
fail trip point both LB and LB will
CC
CC
be driven to ground.
For application information, please reference Application Note 64, published separately.
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