HIT HA16129FPJ Datasheet

HA16129FPJ

Single Watchdog Timer

Description

The HA16129FPJ is a watchdog timer IC that monitors a microprocessor for runaway. In addition to the
watchdog timer function, the HA16129FPJ also provides a function for supplying a high-precision
stabilized power supply to the microprocessor, a power on reset function, a power supply voltage
monitoring function, and a fail-safe function that masks the microprocessor outputs if a runaway is
detected.

Functions

• Watchdog timer (WDT) function

Monitors the P-RUN signal output by the microprocessor, and issues an auto-reset (RES) signal if a
microprocessor runaway is detected.

• Stabilized power supply

Provides power to the microprocessor.

• Power on and clock off functions

The power on function outputs a low level signal to the microprocessor for a fixed period when power
is first applied.

The clock off function outputs a RES signal to the microprocessor a fixed period after a runaway
occurs.

• Power supply monitoring function

When the reference voltage (Vout) falls and becomes lower than the NMI detection voltage (4.63V,
Typ) or the STBY detection voltage (3.0V Typ), this function outputs either an NMI signal or an STBY
signal, respectively. Note that NMI detection can be set to monitor either VCC or Vout.

• OUTE function*1 (fail-safe function)

Outputs a signal used to mask microprocessor outputs when a microprocessor runaway has been
detected.

• RES delay function

Sets the delay between the time the NMI signal is output and the time the RES signal is output.

• Protection functions

The HA16129FPJ incorporates both Vout overvoltage prevention and current limiter functions.

Note: 1. OUTE function: OUTE is an abbreviation for output enable.

HA16129FPJ

Features

• High-precision output voltage: 5.0V ± 1.5%

• The WDT supports both frequency and duty detection schemes.

• High-precision power supply monitoring function: 4.625V ± 0.125V

• Built-in OUTE function

• All functions can be adjusted with external resistors and/or capacitors.

Pin Arrangement

P-RUN

Rf

Cf
R
C

R

C

RES

GND

Voadj

OUTE

20

STBY1
STBYadj

2
3
4

R

5

R

6

T

7
8
9
10

(Top view)

19
18
17
16
15
14
13
12
11

RES

NMI

NMIadj
NMIsns
V

OUT

CONT
CS
V

CC

2

Block Diagram

HA16129FPJ

To microprocessor
(or other device)

V

CC

11

CS CONT

12

13

14

V

OUT

power supply
connections

STBYadj

To Vout

NMIsns

NMIadj

R

C

P-RUN

3.3k

–
+

19

31.2k

36.8k

71k

1.5V

STBY detection
block

15

2k

80k

70k

16

3.3k

–
+

1.18V

25k

NMI detection

T

block

6

150mV

–+

Overcurrent
detection
block

STBY

Q RSRES

tON detection
block

1.24V
–

+

Regulator block

–
+

OUTE
block

Voadj

9

Overvoltage
detection
block

STBY

20
17

NMI

3.3k
10

QRS

OUTE

5

R

If*16

Cf

3

1

If/6

QRS

NMI

–

–

+

–

+

WDT block

I

R

IR*4/3

33k

19k

8.4k

20k

RES block

3.3k

+
–

+

18

7

RES

C

RES

–

8

GND

2V

I

R

4

R

R

If

Delay circuit block

2

Rf

Note: The current, voltage, and resistor values listed in the diagram are reference values.

: Connect to Vout

3

HA16129FPJ

Pin Function

Related
Function

Pin
No. Symbol Function

WDT. 1 P-RUN Watchdog timer pulse input. The auto-reset function is controlled by the

duty cycle or frequency of this input pulse signal.

2 Rf The resistor connected to this pin determines the current that flows in the

Cf pin capacitor. Use the resistor value from 100 kΩ to 500 kΩ

3 Cf The current determined by the Rf pin charges the Cf capacitor and the

potential on this pin determines the watchdog timer frequency band.

tRH, tRL, t

4RRThe resistor connected to this pin determines the current that flows in the

OFF

C

pin capacitor. Use the resistor value from 100 kΩ to 500 kΩ

R

5CRThe current determined by the RR pin charges the capacitor CR and the

potential on this pin controls the RES function (toff, t

t

ON

6RTThe resistor RT, which determines only the time tON for the RES function is

, and tRL).

RH

connected to this pin. This resistor determines the current that charges the

tr, t

RES

7C

RES

capacitor C
The current determined by the Rf pin charges the capacitor C

RES delay times (Tr and T

for the time tON. Use the resistor value from 100 kΩ to 500 kΩ

R

, and the

) are determined by the potential of this

RES

RES

capacitor.
— 8 GND Ground
Vout 9 Voadj Insert the resistor Roadj if fine adjustment of the regulator output voltage

Vout is required. Leave this pin open if Vout does not need to be changed.
Output 10 OUTE Output for the OUTE function
Power

11 V

CC

Power supply
supply

Current
limiter

12 CS Current limiter current detection. Connect the overcurrent detection

resistor between the CS pin and the V

short this pin to V

. Also, connect this pin to the emitter of the external

CC

transistor. (This function can not operate when V

pin. If this function is not used,

CC

< 2 V)

OUT

Vout 13 CONT Connect this pin to the base of the external transistor.

14 V

OUT

Provides the regulator output voltage and the IC internal power supply.

Connect this pin to the collector of the external transistor.
NMI 15 NMIsns This pin senses the NMI detection voltage. If VCC is to be detected,

connect this pin to the V

required), and if Vout is to be detected, connect this pin to the V

pin (however, note that an external resistor is

CC

OUT

pin.

16 NMIadj Insert a resistor if fine adjustment of the NMI detection voltage is required.

Leave this pin open if fine adjustment is not required.
Output 17 NMI NMI output
Output 18 RES RES output
STBY 19 STBYadj Insert a resistor if fine adjustment of the STBY detection voltage is

required. Leave this pin open if fine adjustment is not required.
Output 20 STBY STBY output

4

HA16129FPJ

Functional Description

This section describes the functions provided by the HA16129FPJ. See the section on formulas for details
on adjustment methods.

Regulator Block

Vout Voltage
This IC provides a stabilized 5V power supply by controlling the base current of an external transistor. The
largest current (the maximum CONT pin current) that can be drawn by the base of this external transistor is
20mA. Also note that the Vout output is also used for the power supply for this IC’s internal circuits.

Current Limiter Block

When a current detection resistor (RCS) is connected between the VCC pin and the CS pin, and the voltage
between these pins exceeds the VCS voltage (150mV Typ), the CONT pin function turns off and the output
voltage supply is stopped. This function can not work when V

Output Voltage (Vout) Adjustment

The output voltage can be adjusted by connecting an external resistor at the output voltage adjustment pin
(Voadj). However, if for some reason the voltage on this Vout line increases and exceeds the voltage
adjustment range (7V Max), the CONT pin function turns off and the output voltage supply is stopped.

OUT

< 2V.

Refer to the timing charts in conjunction with the following items.

LVI (Low Voltage Inhibit)

NMI Detection Voltage
This function monitors for drops in the power-supply voltage. This function can be set up to monitor either
VCC or Vout. When Vout is monitored, a low level is output from the NMI pin if that voltage falls under the
detection voltage (4.63V Typ). Then, when the power-supply voltage that fell rises again, the NMI pin will
output a high level. Note that this function has a fixed hysteresis of 50mV (Typ). The monitored power
supply is selected by connecting the NMIsns pin either to the VCC pin or to the V

pin. When detecting

OUT

VCC, an external adjustment resistor is required.)

The detection voltage can also be adjusted with the NMIadj pin.

STBY Detection Voltage
This function monitors for drops in the Vout voltage. It monitors the Vout voltage, and outputs a low level
from the STBY pin if that voltage drops below the detection voltage (3.0V Typ). Then, when the power­supply voltage that fell rises again, the STBY pin will output a high level. Note that this function has a
fixed hysteresis of 1.35V (Typ).

The detection voltage can also be adjusted with the STBYadj pin.

5

HA16129FPJ

Function Start Voltage

This is the minimum required Vout voltage for the RES, NMI, STBY, and OUTE output pin functions to
start operating. It is stipulated as the voltage that Vout must reach after power is first applied for these pins
to output a low level.

Hysteresis

This is the difference between the LVI function detection voltage when the power-supply voltage drops,
and the clear (reset) voltage when the power-supply voltage rises.

(V

= V

' – V

; V

= V

HYSN

NMI

NMI

HYSS

STBY

' – V

OUTE Function

When a microprocessor is in the runaway state, its outputs are undefined, and thus it is possible that the
outputs may be driven by incorrect signals. This function is used to mask such incorrect microprocessor
outputs. When the WDT function recognizes normal operation (when the RES output is high), the OUTE
output will be held high. When the WDT function recognizes an abnormal state and an auto-reset pulse is
output from the RES pin, the OUTE output will be held low. Thus microprocessor outputs during
microprocessor runaway can be masked by taking the AND of those outputs and this signal using external
AND gates.

STBY

)

The OUTE output will go high when the CR pin voltage exceeds VthHcr2, and will go low when that
voltage falls below VthLcr.

There are limitation that apply when the OUTE function is used. Refer to the calculation formulas item for
details.

RES Function

t

RH

This period is the length of the high-level output period of the RES pulse when the P-RUN signal from the
microprocessor stops. This is the time required for the CR potential to reach VthLcr from VthHcr1.

t

RL

This period is the length of the low-level output period of the RES pulse when the P-RUN signal from the
microprocessor stops. This is the time required for the CR potential to reach VthHcr1 from VthLcr.

t

OFF

This is the time from the point the P-RUN signal from the microprocessor stops to the point a low level is
output from the RES pin. During normal microprocessor operation, the potential on the CR pin will be
about Vout – 0.2V (although this value may change with the P-RUN signal input conditions, so it should be
verified in the actual application circuit) and t

is the time for the CR pin potential to reach VthLcr from

OFF

that potential.

6

HA16129FPJ

t

ON

tON is the time from the point the NMI output goes high when power is first applied to the point the RES
output goes low. tON is the time for the potential of the CR pin to reach VthHcr1 from 0V.

tr
The time tr is the fixed delay time between the point the NMI output goes from low to high after the power­supply voltage comes up to the point RES goes from low to high. The time tr is the time for the CRES pin
potential to fall from the high voltage (about 1.9V) to Vthcres.

t

RES

The time t
power-supply voltage falls to the point RES goes from high to low. The time t
potential to rise from 0V to Vthcres.

WDT Function

This function determines whether the microprocessor is operating normally or has entered a runaway state
by monitoring the duty or frequency of the P-RUN signal. When this function recognizes a runaway state,
it outputs a reset pulse from the RES pin and sets the OUTE pin to low from high. It holds the RES and
OUTE pins fixed at high as long as it recognizes normal microprocessor operation.

is the fixed delay time between the point the NMI output goes from high to low when the

RES

is the time for the C

RES

RES

pin

In this function, the potential of the Cf capacitor is controlled by the P-RUN signal. This Cf pin potential
charges the capacitor CR that controls the reset pulse to be between VthLcf and VthHcf. The judgment as
to whether or not the microprocessor is operating normally, is determined by the balance between the
charge and discharge voltage on the capacitor CR at this time.

7

HA16129FPJ

Calculation Formulas

Item Formula Notes

Reference
voltage

Vout = 1.225 1 +

(

R1, R2; kΩ

37 // R1
12 // R2

While the Vout voltage will be 5 V ±1.5% when the

(

Voadj pin is open, the circuit shown here should be
used to change the Vout voltage externally.

R1

R2

Current
limiter
voltage

V

(150 mV Typ) < IL · R

CS

CS

VCCCS Vout

Voadj

When this function operates, the base current to the
external transistor connected to the CS pin stops and
the Vout output is lowered.

R

CSIL

VCCCS Vout

OVP — This function prevents the microprocessor from being

damaged if the Vout voltage is inadvertently increased
to too high a level. The OVP detection voltage is fixed.

tRH, t

t

ON

RL

tRH

= 3.3 × C

t

= 1.1 × CR · R

RL

R

· R

tON = 1.1 × CR · R

R
R

T

These determine the reset pulse frequency and duty.

t

RL

RES

t

RH

Sets the time from the rise of the NMI signal to the point
the RES output is cleared.

NMI

t

RES

t

t

OFF

= 6.5 × CR · R

OFF

R

Sets the time from the point the P-RUN pulse stops to

ON

the point a reset pulse is output.

P-RUN

RES

toff

8