ds1259st-r Maxim Integrated Products, Inc., ds1259st-r Datasheet - Page 2

• Manufacturer Part Number: ds1259st-r
• Description: Ds1259 Battery Manager Chip
• Manufacturer: Maxim Integrated Products, Inc.

DS1259
OPERATION
During normal operation, V
(Pins 15 and 16) is the primary energy source and power is supplied to
CCI
V
(Pins 12 and 13) through an internal switch at a voltage level of V
-0.2 volts at 250 mA. During
CCO
CCI
this time the power-fail signal (
) is held high, indicating valid V
voltage (see Figure 1). However, if
PF
CCI
the V
falls below the trip point (V
), a level of 1.26 times the battery level (V
), the power-fail
CCI
TP
BAT
signal is driven low. As V
falls below the battery level, power is switched from V
to V
and the
CCI
CCI
BAT
battery supplies power to the uninterruptible output (V
) at V
-0.2 volts at 15 mA.
CCO
BAT
On power-up, as the V
supply rises above the battery, the primary energy source, V
, becomes the
CCI
CCI
supply. As V
rises above the trip point (V
), the power fail signal is driven back to the high level.
CCI
TP
During normal operation, BAT (Pin 5) stays at the battery level regardless of the level of V
.
CCI
BATTERY FAIL
When power is being supplied from the primary energy source,
(Pin 3) is held at a high level,
BF
provided that the attached battery (V
) is greater than 2 volts. If the battery level should decrease to
BAT
below 2 volts, the
signal is driven low, indicating a low battery. The
signal is always low when
BF
BF
the
signal is low.
PF
RESET
The reset input can be used to prevent the battery from supplying power to V
and BAT even if V
CCO
CCI
falls below the level of the battery. This feature is activated by applying a pulsed input on RST to high
level for 50ns minimum while primary power is valid (see Figure 2). When primary power is removed
after pulsing RST, the V
output and BAT will go to high impedance. The next time primary power is
CCO
applied such that V
is greater than V
, normal operation resumes and V
will be supplied by the
CCI
BAT
CCO
battery or V
. The BAT output will also return to the level of the battery. Figure 3 shows the DS1259 in
CCI
a typical application.
BLOCK DIAGRAM Figure 1
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