INTEGRATED CIRCUITS
SA56600-42
System reset for lithium battery backup
Product data
Supersedes data of 2001 Apr 24
File under Integrated Circuits, Standard Analog
2001 Jun 19
Philips
Semiconductors
Philips Semiconductors
Product data
System reset for lithium battery back-up
SA56600-42
GENERAL DESCRIPTION
The SA56600-42 is designed to protect SRAM data in computer
systems during periods of sagging power supply voltages and power
outages. When the power supply voltage drops to typically 4.2 V, the
CS output goes to a logic LOW state pulling CE to a LOW state,
disabling the SRAM device. In addition, a reset logic LOW is asserted
for system use. If the supply voltage drops further, to 3.3 V typically
or lower, the SA56600-42 switches the system’s operation from the
main power supply source to the Lithium back-up battery. As the
main supply is restored and the voltage rises to 3.3 V or higher, the
SRAM support voltage transfers from the Lithium back-up battery to
the main supply. When the main supply voltage rises to greater than
typically 4.2 V, the CS output goes to a logic HIGH state for SRAM
CE control. Reset assertion is released and normal operation is
resumed. This sequence ensures reliable preservation of SRAM
data during periods of supply deficiency and interruptions.
The SA56600-42 is offered in the SO8 surface mount package.
FEATURES
•
Supply switching at 4.2 V
DC
threshold (falling supply)
•
RESET output
•
Both CS and CS outputs available for SRAM control
•
During battery back-up operation:
–
Low supply current (0.3
µA
typical)
–
Low input/output voltage drop (0.3 V typical at 100
µA)
–
Low reverse current leakage (0.1
µA
max.)
During normal operation:
–
Low input/output voltage drop (0.2 V typical at 50 mA)
–
4.8 V typical output voltage at 50 mA with V
CC
= 5.0 V
–
Restoration of main supply operation at 3.3 V
APPLICATIONS
•
Memory cards (SRAM)
•
PCs, word processors
•
FAX machines, photocopiers, office equipment
•
Sequence controllers
•
Video games and other equipment with SRAM
•
SIMPLIFIED SYSTEM DIAGRAM
SA56600-42
V
CC
8
6
4
V
OUT
V
BATT
V
CC
3.3 V
DETECTION
CITCUIT
R
PU
2
RESET
LITHIUM
BATTERY
R
V
DD
SRAM
3
4.2 V
DETECTION
CITCUIT
GND
1
7
Y
5
CS
CE
GND
CS
SL01277
Figure 1. Simplified system diagram.
ORDERING INFORMATION
TYPE NUMBER
SA56600-42D
PACKAGE
NAME
SO8
DESCRIPTION
plastic small outline package; 8 leads; body width 3.9 mm
2
TEMPERATURE
RANGE
–40 to +85
°C
853–2249 26559
2001 Jun 19
Philips Semiconductors
Product data
System reset for lithium battery back-up
SA56600-42
Part number marking
The package is marked with a four letter code in the first line to the
right of the logo. The first three letters designate the product. The
fourth letter, represented by ‘x’, is a date tracking code. The
remaining two or three lines of characters are internal manufacturing
codes.
PIN CONFIGURATION
TOP VIEW
GND
RESET
CS
V
BATT
7
6
1
2
8
7
V
CC
Y
V
OUT
CS
SO8
3
4
6
5
8
5
SL01278
Figure 2. Pin configuration.
1
2
3
Part number
SA56600-42
Marking
AAA x
PIN DESCRIPTION
PIN
1
2
3
4
5
6
7
8
SYMBOL
GND
RESET
CS
V
BATT
CS
V
OUT
Y
V
CC
Circuit ground for the device.
Asserted open collector output LOW whenever the V
CC
input source voltage falls below V
S
(4.2 V typical).
The open collector topology requires an external pull-up resistor.
Chip select HIGH output signal, asserted whenever the V
CC
input source voltage is above V
S
(4.2 V typical).
Can be used as a chip enable HIGH (CE) signal for system SRAM.
Positive polarity connection for lithium back-up battery.
Asserted chip select LOW output signal whenever the V
CC
input source voltage is above V
S
(4.2 V typical)
and Y is grounded. Can be used as a chip enable LOW (CE) signal for system SRAM.
Primary power with lithium battery back-up power for the protected system. Switch over to lithium battery
back-up operation occurs when V
CC
falls below V
S
.
Open Emitter input to microcontroller used to enable CS output (microcontroller controls CS function).
Primary input power source for device.
DESCRIPTION
MAXIMUM RATINGS
SYMBOL
V
CC(max)
V
CC(op)
I
O
(V
CC
)
I
O
(V
BATT
)
T
oper
T
stg
P
Power supply voltage
Operating voltage
Output current
Output current
Operating temperature
Storage temperature
Power dissipation
PARAMETER
RATING
–0.3 to +7.0
–0.3 to +7.0
80
200
–40 to +85
–40 to +125
250
UNIT
V
V
mA
µA
°C
°C
mW
4
2001 Jun 19
3
Philips Semiconductors
Product data
System reset for lithium battery back-up
SA56600-42
ELECTRICAL CHARACTERISTICS
Characteristics measured with V
CC
= 5.0 V, and T
amb
= 25
°C,
unless otherwise specified.
SYMBOL
I
CC
V
SAT1
V
O1
V
O2
V
S
∆V
S
V
RSL
I
RSH
V
OPL
V
CSL
V
CSH
V
CSL
V
CSH
∆V
S
/∆T
V
BT
V
BT(HYS)
V
BT
/∆T
I
L
V
SAT2
V
O3
V
O4
V
REF
I
BL
I
YLO
t
PLH
t
PHL
PARAMETER
Supply current
I/O voltage difference 1
Output voltage 1
Output voltage 2
Detection threshold
Detection hysteresis
Reset output LOW
Reset leakage current HIGH
Reset assertion
(minimum operating voltage)
CS output voltage LOW
CS output voltage HIGH
CS output voltage LOW
CS output voltage HIGH
Detection voltage temperature
characteristic
Battery back-up threshold
Battery back-up hysteresis
Switching voltage temperature
characteristic
Loss current
I/O voltage difference 2
Output voltage 3
Output voltage 4
Reference voltage (typical)
V
BATT
leakage current
Y current
Y propagation delay time (Note 1)
Y propagation delay time (Note 1)
V
CC
= 5.0 V; V
BATT
= 0 V
V
CC
= 5.0 V; V
BATT
= 3.0 V; V
Y
= 0 V
VY = logic LOW to logic HIGH
VY = logic HIGH to logic LOW
CONDITIONS
V
CC
= 5.0 V; V
BATT
= 3.0 V; I
O
= 0 mA
V
CC
= 5.0 V; V
BATT
= 3.0 V; I
O
= 1.0 mA
V
CC
= 5.0 V; V
BATT
= 3.0 V; I
O
= 1.0 mA
V
CC
= 5.0 V; V
BATT
= 3.0 V; I
O
= 15 mA
V
CC
falling
∆V
S
= V
SH
(rising V
CC
) – V
SL
(falling V
CC
)
V
CC
= 3.7 V
V
CC
= 5.0 V; V
RS
= 7.0 V
V
RSL
≤
0.4 V; V
CC
falling; R
PU
= 10 kΩ
V
CC
= 3.7 V; V
BATT
= 3.0 V; I
CS
= 1.0
µA
V
CC
= 5.0 V; V
BATT
= 3.0 V; I
CS
= –1.0
µA
V
CC
= 5.0 V; V
BATT
= 3.0 V; I
CS
= 1.0
µA
V
CC
= 3.7 V; V
BATT
= 3.0 V; I
CS
= –1.0
µA
–40
≤
T
amb
≤
+85
V
CC
falling
V
BT(HYS)
=
V
BTH
(V
CC
rising) – V
BTL
(V
CC
falling)
–40
≤
T
amb
≤
+85
V
CC
= 0 V; V
BATT
= 3.0 V; I
O
= 0
µA
V
CC
= 0 V; V
BATT
= 3.0 V; I
O
= 1.0
µA
V
CC
= 0 V; V
BATT
= 3.0 V; I
O
= 1.0
µA
V
CC
= 0 V; V
BATT
= 3.0 V; I
CS
= 100
µA
MIN.
–
–
4.95
4.75
4.00
–
–
–
–
–
4.90
–
V
O
– 0.1
–
3.15
–
–
–
–
2.7
2.6
–
–
–
–
–
TYP.
1.4
0.03
4.97
4.90
4.20
100
0.2
±0.01
0.8
–
–
–
–
–
3.30
100
–
0.3
0.2
2.8
2.7
1.25
–
150
8.0
8.0
MAX.
2.2
0.05
–
–
4.40
–
0.4
±0.1
1.2
0.1
–
0.2
–
±0.05
3.45
1.0
±0.05
0.5
0.3
–
–
–
0.1
400
20
20
UNIT
mA
V
V
V
V
mA
V
µA
V
V
V
V
V
%/°C
V
mV
%/°C
µA
V
V
V
V
µA
µA
ns
ns
NOTE:
1. Y input rise and fall time less than 6.0 ns. 15 pF capacitance load on CS (Pin 5 to GND).
2001 Jun 19
4
Philips Semiconductors
Product data
System reset for lithium battery back-up
SA56600-42
TYPICAL PERFORMANCE CURVES
5.0
T
amb
= –40
°C
V
OUT
, OUTPUT VOLTAGE (V)
4.9
V
CC
= 5.0 V
V
BATT
= 3.0 V
V
OUT
, OUTPUT VOLTAGE (V)
5.3
5.2
5.1
5.0
4.9
40 mA
4.8
4.7
4.6
4.5
0
10
20
30
40
50
60
70
80
I
OUT
, OUTPUT CURRENT (mA)
4.5
–50
80 mA
60 mA
I
OUT
= 0 mA
20 mA
V
CC
= 5.0 V
V
BATT
= 3.0 V
RESET, RESET, CS, CS = OPEN
Y = GND
4.8
4.7
T
amb
= 25
°C
T
amb
= 85
°C
T
amb
= 125
°C
4.6
–25
0
25
50
75
100
125
T
amb
, TEMPERATURE (°C)
SL01330
SL01332
Figure 3. Output voltage versus output current.
Figure 4. Output voltage versus temperature.
3.0
2.9
V
O
, OUTPUT VOLTAGE (V)
2.8
2.7
2.6
2.5
2.4
2.3
0
T
amb
= 25
°C
T
amb
= –40
°C
200
400
600
800
1000
V
CC
= 0 V
V
BATT
= 3.0 V
V
O
, OUTPUT VOLTAGE (V)
3.0
2.9
2.8
200
µA
2.7
2.6
2.5
2.4
1000
µA
2.3
–50
–25
0
25
50
75
100
125
400
µA
600
µA
800
µA
V
CC
= 0 V
V
BATT
= 3.0 V
RESET, RESET, CS, CS = OPEN
Y = GND
I
OUT
= 1.0
µA
T
amb
= 125
°C
T
amb
= 85
°C
I
O
, OUTPUT CURRENT (mA)
T
amb
, TEMPERATURE (°C)
SL01331
SL01333
Figure 5. Output voltage versus current.
Figure 6. Output voltage versus temperature.
5.0
4.5
I
CC
, SUPPLY CURRENT (mA)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
V
OUT
= OPEN
V
BATT
= 3.0 V
T
amb
= 25
°C
I
BATT
, BATTERY CURRENT (nA)
15
I
O
= 0 mA
V
BATT
= 3.0 V
T
amb
= 25
°C
10
5.0
0
–5.0
–10
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10
0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
V
CC
, SUPPLY VOLTAGE (V)
V
CC
, SUPPLY VOLTAGE (V)
SL01334
SL01335
Figure 7. Supply current versus supply voltage.
Figure 8. Battery current versus supply voltage.
2001 Jun 19
5
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