TA8030S/F
2002-02-27
1
TOSHIBA BIPOLAR LINEAR INTEGRATED CIRCUIT SILICON MONOLITHIC
TA8030S,TA8030F
WATCHDOG TIMER
The TA8030S TA8030F is a system reset IC for 5V supply
voltage system. It is specially designed for microcomputer systems.
It incorporates a watchdog timer for monitoring microcomputer
operation and has many reset functions, including a reset timer
output which will be given at power-on and another reset output
which will be given when the supply voltage drops. With these
functions, it helps build up a reliable system.
FEATURES
l Watchdog timer
l Power-on reset timer
l Dual-reset output
l SIP7 PIN (TA8030S)
SOP8 PIN (TA8030F)
TA8030S
TA8030F
Weight
SIP7- P-2.54A : 0.7g (typ.)
SOP8- P-225-1.27 : 0.08g (typ.)
TA8030S/F
2002-02-27
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BLOCK DIAGRAM AND PIN LAYOUT
Note: The TA8030S and TA8030F are the same chip; only the packages are different.
TA8030S/F
2002-02-27
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PIN DESCRIPTION
PIN No.
TA80305 TA8030F SYMBOL DESCRIPTION
1 1 WD
Clock input pin for watchdog timer. If this IC is only used as a power-on reset timer, this
pin is connected to RST1 .
2 2 TC Time setting pin for the reset and watchdog timers. R1 leads to VCC, and C1leads to
GND.
3 3 RST1
Supplies an NPN transistor open-collector output.
● Generates a reset signal determined by the CR combination connected to the TC pin.
● Supplies reset pulses intermittently if no clock is given to the WD pin.
4 4 GND Grounded
5 6 ADJ
VCC detect voltage (1) adjusting pin. The detection voltage is 4.6V when this pin is
grounded ; it is 3.5V when this pin is directly connected to VCC.
6 7 VCC Power supply pin for internal circuit. The output voltage can also be detected at this pin.
7 8 RST2 Supplies an NPN transistor open-collector output. It is the output pin for VCC detect
voltage (2) . The detect voltage has a hysteresis of 0.17V.
― 5 NC Not connected pin.(Electrically,this pin is completely open.)
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FUNCTIONAL DESCRIPTION
About reset timer operation (See the timing chart)
The following explains the TA8030S/F's voltage monitoring and reset timer operations and how to use these
functions.
(1) Voltage monitoring function (1)
The power input VCC pin of this IC also serves as a voltage detection pin. When the VCC voltage exceeds
4.25V after the IC is powered on, the power-on reset timer starts operating from that point in time. When
the IC is powered off and VCC drops below 4.25V, TC starts discharging and a reset signal is output when
the voltage drops below 40% of VCC. Also, if VCC goes down for some reason during normal operation, a
reset signal is output in the same way as described above, and when VCC is up again and exceeds 4.25V, the
power-on reset timer starts operating from that point in time.
The reset signal is forwarded to the 1RST pin.
(2) Voltage monitoring function (2)
The 2RST pin outputs a high when the VCC voltage rises above 4.65V and outputs a low when it falls below
4.48V. This function only monitors the voltage operating independently of Voltage monitoring function (1)
and the reset timer function. Since when the voltage drops the 2RST output is inverted before a system
reset signal is output from 1RST , this function can be used to inhibit writing to memory.
Also, this voltage detection has 3μs of response delay, td2, to prevent a reset from being generated
inadvertently by minute noise. (For td2, refer to AC Electrical Characteristics.)
(3) Power-on reset timer function
The device is held in a reset state for a predetermined time until the 5V constant voltage stabilizes at
power-on and until the oscillating clock of the CPU, etc. stabilizes before being freed from the reset state.
This time can be set to any desired duration by using the appropriate resistor and capacitor values
connected external to the TC pin.
When the VCC voltage exceeds 4.25V, the system starts charging the capacitor and when this charging
voltage exceeds 2V, the reset signal is inverted to deactivate the reset.
(4) Watchdog timer function
The WD pin between the CPU system and this IC is connected with an differential circuit. This is to ensure
that when a failure occurs in the CPU system, a low signal is input to the WD pin no matter whether the
clock output has stopped in the high or the low state. When the WD pin is fixed high, the watchdog timer
stops operating.
If only the power-on reset timer is needed in your system, connect the WD pin to 1RST .
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TIMING CHART
Note : See Electrical Characteristics for symbols in the timing chart.
TA8030S/F
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MAXIMUM RATINGS (Ta = 25°C)
CHARACTERISTIC SYMBOL RATING UNIT
Supply Voltage VCC 17 V
Input Voltage VIN (CK) −7～7 V
Output Voltage VOUT 7 V
Output Current IOUT 10 mA
Power Dissipation PD 300/280 mW
Operating Temperature Topr −40 to 85 ℃
Storage Temperature Tstg −55 to 150 ℃
Lead Temperature-time Tsol 260 (10s) ℃
Note: PD : TA8030S/TA8030F
ELECTRICAL CHARACTERISTICS (VCC = 5V, Ta = −40 to 85°C)
(1) DC CHARACTERISTICS
CHARACTERISTIC SYMBOL PIN
TEST
CIR-
CUIT
TEST CONDITION MIN TYP. MAX UNIT
IIH 1 VIN = 5V 0.1 0.17 0.35
Input Current
IIL
WD
1 VIN = −5V −0.06 −0.1 −0.2
mA
VIH 2 ― 2.2 ― ―
Input Voltage
VIL
WD
2 ― ― ― 0.6
V
Input Current IIN TC 4 VIN = 1.5V −2 ― 2 µA
Output Current IOUT TC 4 VOUT = 4.2V 2.4 4 7.7 mA
VTH3 (H) 3 ― 3.5 4 4.5
Watchdog Timer Threshold
Voltage VTH3 (L)
TC
3 ― 1.75 2 2.25
V
Output Voltage VOL RST1 5 IOUT = 2mA ― ― 0.5 V
Output Leakage Current ILEAK RST2 6 VOUT = 7V ― ― 5 µA
VTH1 ― ― 4.0 4.25 4.5
VTH1 (H) 3 AJD = GND 4.3 4.6 4.9
VCC Detect Voltage (1)
VTH1 (L)
VCC
3 ADJ = VCC 3.25 3.5 3.75
V
VTH2 (H) 3 ― 4.4 4.65 4.9
VCC Detect Voltage (2)
∆VTH2
VCC
3 ― ― 0.17 0.3
V
Current Consumption ICC V
CC 7 ― ― 2.5 4.5 mA
(2) AC CHARACTERISTICS
CHARACTERISTIC SYMBOL PIN
TEST
CIR-
CUIT
TEST CONDITION MIN TYP. MAX UNIT
Watchdog Timer TWD RST1 3
0.9 ×
C1R1
1.1 ×
C1R1
1.3 ×
C1R1 ms
Reset Timer (1) TRST (1) RST1 3
0.4 ×
C1R1
0.5 ×
C1R1
0.6 ×
C1R1 ms
Reset Timer (2) TRST (2) RST1 3
0.35 ×
C1
0.75 ×
C1
1.5 ×
C1 ms
Input Pulse Width TW WD 3 3 ― ― μs
td1 RST1 3 tdHL (C1 = 0μF) ― 3 10
Transfer Delay Time td2 RST2 3 tdHL, tdLH ― 3 10
μs
Note:The unit for the C1 is μF、the unit for R1 is kΩ.
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TEST CIRCUIT (Number in ○
○○
○ show pin number of the TA8030S, those in (
) show pin
number of the TA8030F.)
1. IIH、
、、
、IIL (WD)
2. VIH、
、、
、VIL (WD)
3. VTH3 (H)、
、、
、(L) (TC)、
、、
、VTH1、
、、
、VTH1 (H)、
、、
、(L)、
、、
、VTH2 (H)、Δ
、Δ、Δ
、ΔVTH2、
、、
、AC CHARACTERISTICS
4. IIN、
、、
、IOUT (TC)
TA8030S/F
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5. VOL ( 1RST ) ( 2RST )
6. ILEAK (1RST ) ( 2RST )
7 ICC
8. VOL (1)、
、、
、(2) ( 1RST ) ( 2RST )
TA8030S/F
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RESET OUTPUT STANDARD CHARACTERISTICS
1. 1RST 2.
2RST
ADJ PIN PULL-UP / DOWN RESISTANCE VS VCC DETECT VOLTAGE
TA8030S/F
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EQUIVALENT CIRCUIT DIAGRAM (WATCHDOG TIMER)
EXAMPLE OF APPLICATION CIRCUIT
RECOMMENDED CONDITIONS
PART NAME MIN TYP. MAX UNIT
C1 0.01 100 μF
R1 10 100 kΩ
C2 2200 pF
TA8030S/F
2002-02-27
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Package Dimensions
Weight: 0.7g (Typ.)
TA8030S/F
2002-02-27
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Package Dimensions
Weight: 0.08g (Typ.)
TA8030S/F
2002-02-27
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000707E
A
A_S
RESTRICTIONS ON PRODUCT USE
