Dallas Semiconductor DS1239S-5N, DS1239S-5, DS1239S-10, DS1239-5, DS1239-10 Datasheet

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FEATURES

 Provides necessary control for start up and

shutdown of power supply from keyboard

 Holds microprocessor in check during power

transients

 Halts and restarts an out-of-control

microprocessor

 Monitors push button for external override
 Warns microprocessor of an impending power

failure

 Converts CMOS SRAM into nonvolatile

memory

 Unconditionally write-protects memory when

power supply is out of tolerance

 Consumes less than 100 nA of battery current
 Controls external power switch for high

current applications

 Accurate 10% power supply monitoring
 Optional 5% power supply monitoring

designated DS1239-5

 Provides orderly shutdown in nonvolatile

microprocessor applications

 Supplies necessary control for low-power

“stop mode” in battery operate hand-held
applications

 Standard 16-pin DIP or space-saving 16-pin

SOIC

 Optional industrial temperature range -40°C

to +85°C

PIN ASSIGNMENT

PIN DESCRIPTION

V

BAT

- +3 Volt Battery Input

V

CCO

- Switched SRAM Supply Output
VCC - +5 Volt Power Supply Input
GND - Ground
PF - Power Fail (Active High)

PF - Power Fail (Active Low)

WC/

SC - Wake-Up Control (Sleep)

PSI - Power Supply Control Input

IN - Early Warning Input

NMI - Non-Maskable Interrupt
ST - Strobe Input

CEO - Chip Enable Output
CEI - Chip Enable Input
PBRST - Pushbutton Reset Input
RST - Reset Output (Active low)

PSO - Power Supply Control Outputs

DESCRIPTION

The DS1239 MicroManager provides all the necessary functions for power supply control and
monitoring, reset control, and memory backup in microprocessor-based systems. Using the DS1239, an
AC power switch is no longer required for microprocessor-based systems. A keyboard control system for
power supply start up and shutdown is provided through the use of the Power Suppl y Control Input and
Output. In other respects, the DS1239 is functionally identical to a DS1236 in the NMOS mode. For a
complete description of the other DS1239 features, refer to the DS1236 data sheet. Pin-out of the

DS1239

MicroManager Chip

www.dalsemi.com

DS1239 16-Pin SOIC (300-mil)

See Mech. Drawings Section

VBAT

VCCO

VCC

PSO
RST
PBRST

1
2
3

16
15
14

GND CEI413

PF
PF

WC/SC

CEO
ST
NMI

5
6
7

12
11
10

PSI IN

89

DS1239 16-Pin DIP (300-mil)

See Mech. Drawings Section

VBAT

VCCO

VCC

PSO
RST
PBRST

1
2
3

16
15
14

GND CEI413

PF
PF

WC/SC

CEO
ST
NMI

5
6
7

12
11
10

PSI IN89

DS1239

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DS1239 is identical to the DS1236 with two exceptions. The RC and RST pins have been replaced with

PSI and PSO, respectively. Other pins and functions operate exactly as the DS1236 in NMOS mode.

POWER SUPPLY CONTROL

The DS1239 facilitates the power-up and power-down sequencing of a main power supply from a
keyboard or pushbutton. The Power Supply Control Input (

PSI ) and Powe r Supply Control Output (PSO)

are used for this purpose. Prior to establishing a voltage on VCC (+5V), the PSI is internally held at a high
level at all times with the V

BAT

supply. When PSI is forced low via a keypad or other source, the PSO is

connected to the V

BAT

to provide a high level. As shown in Figure 1, this active hi gh signal can be wired

directly to an optically isolated SCR to initiate an AC to DC power-up sequence. This in turn will provide
the supply voltage for VCC. The timing is illustrated in Figure 2. Holding the PSI input low, the PSO

output will supply a connection to the V

BAT

pin until the VCC reaches V

BAT

, or a maximum of 500 ms. If

the supply voltage on VCC rises above the V

BAT

level before the t

PSI

timeout, the PSO pin will remain high

and track the VCC input. If VCC does not rise above V

BAT

before either t

PSI

or PSI is allowed to return to a

high level, the PSO output will return to tristate. Once the PSO output and V

CC

are set at a high level, a
subsequent falling edge on PSI will tristate PSO to initiate a shut down condition. The 10 microamp
current supplied by the

PSI pin allows the use of a 0.1 µF capacitor as a simple pushbutton debounce

circuit. The battery size for this application must be selected to provide the SCR on-current for the power
supply response time and is consequently application-specific.

POWER SUPPLY CONTROL Figure 1