DataSheet.es    


PDF LM2984 Data sheet ( Hoja de datos )

Número de pieza LM2984
Descripción Microprocessor Power Supply System
Fabricantes National Semiconductor 
Logotipo National Semiconductor Logotipo



Hay una vista previa y un enlace de descarga de LM2984 (archivo pdf) en la parte inferior de esta página.


Total 16 Páginas

No Preview Available ! LM2984 Hoja de datos, Descripción, Manual

April 1998
LM2984
Microprocessor Power Supply System
General Description
The LM2984 positive voltage regulator features three inde-
pendent and tracking outputs capable of delivering the
power for logic circuits, peripheral sensors and standby
memory in a typical microprocessor system. The LM2984 in-
cludes circuitry which monitors both its own high-current out-
put and also an external µP. If any error conditions are
sensed in either, a reset error flag is set and maintained until
the malfunction terminates. Since these functions are in-
cluded in the same package with the three regulators, a
great saving in board space can be realized in the typical mi-
croprocessor system. The LM2984 also features very low
dropout voltages on each of its three regulator outputs (0.6V
at the rated output current). Furthermore, the quiescent cur-
rent can be reduced to 1 mA in the standby mode.
Designed also for vehicular applications, the LM2984 and all
regulated circuitry are protected from reverse battery instal-
lations or 2-battery jumps. Familiar regulator features such
as short circuit and thermal overload protection are also pro-
vided. Fixed outputs of 5V are available in the plastic TO-220
power package.
Features
n Three low dropout tracking regulators
n Output current in excess of 500 mA
n Fully specified for −40˚C to +125˚C operation
n Low quiescent current standby regulator
n Microprocessor malfunction RESET flag
n Delayed RESET on power-up
n Accurate pretrimmed 5V outputs
n Reverse battery protection
n Overvoltage protection
n Reverse transient protection
n Short circuit protection
n Internal thermal overload protection
n ON/OFF switch for high current outputs
n P+ Product Enhancement tested
Typical Application Circuit
DS011252-1
COUT must be at least 10 µF to maintain stability. May be increased without bound to maintain regulation during transients. Locate as close as possible to
the regulator. This capacitor must be rated over the same operating temperature range as the regulator. The equivalent series resistance (ESR) of this
capacitor is critical; see curve.
Order Number LM2984T
See NS Package Number TA11B
© 1998 National Semiconductor Corporation DS011252
www.national.com

1 page




LM2984 pdf
Electrical Characteristics (Continued)
VIN = 14V, IOUT = 5 mA, Ibuf = 5 mA, Istby =
Boldface type refers to limits over the entire
5 mA, Rt
operating
= 130 k, Ct
temperature
= 0.33 µF, Cmon =
range, −40˚C TA
0.47 µF, unless otherwise indicated,
+125˚C, all other limits are for TA =
TJ
= 25˚C (Note 8)
Parameter
Conditions
Typical
Limit
Units
Computer Monitor/Reset Functions
Reset Rise Time
On/Off Switch Input
Current (Pin 8)
On/Off Switch Input
Rrst = 10k, Vrst = 5V, Crst 10 pF
VON = 2.4V
VON = 0.4V
Threshold Voltage
0.60
7.5
0.01
1.22
1.22
(Note 4)
1.00/1.50
25/25
10/10
0.80/0.80
2.00/2.00
µsmax
µAmax
µAmax
Vmin
Vmax
Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its specified operating ratings.
Note 3: Thermal resistance without a heatsink for junction-to-case temperature is 3˚C/W. Thermal resistance case-to-ambient is 40˚C/W.
Note 4: Tested Limits are guaranteed and 100% production tested.
Note 5: Human body model, 100 pF capacitor discharged through a 1500resistor.
Note 6: Internal comparators detect when the main regulator output (VOUT) changes from the measured output voltage (with VIN = 14V) by the specified amount,
VOUT High or VOUT Low, and set the Reset Error Flag low. The Reset Error Flag is held low until VOUT returns to regulation. The Reset Error Flag is then allowed
to go high again after a delay set by Rtand Ct. (see application section).
Note 7: This parameter is a measure of how short a pulse can be detected at the µP Monitor Input. This parameter is primarily influenced by the value of Cmon. (See
Application Hints Section.)
Note 8: To ensure constant junction temperature, low duty cycle pulse testing is used.
Block Diagram
DS011252-2
5 www.national.com

5 Page





LM2984 arduino
Typical Performance Characteristics (Continued)
Ripple Rejection (VOUT)
Ripple Rejection (Vbuf)
Ripple Rejection (Vstby)
Output Voltage
DS011252-49
DS011252-50
Device Dissipation vs
Ambient Temperature
DS011252-51
Output Capacitor ESR
(Standby Output, Pin 9)
DS011252-8
Output Capacitor ESR
(Buffer Output, Pin 10)
DS011252-9
Output Capacitor ESR
(Main Output, Pin 11)
DS011252-10
Application Hints
OUTPUT CAPACITORS
The LM2984 output capacitors are required for stability.
Without them, the regulator outputs will oscillate, sometimes
by many volts. Though the 10 µF shown are the minimum
recommended values, actual size and type may vary de-
pending upon the application load and temperature range.
Capacitor effective series resistance (ESR) also affects the
IC stability. Since ESR varies from one brand to the next,
some bench work may be required to determine the mini-
DS011252-11
DS011252-12
mum capacitor value to use in production. Worst case is usu-
ally determined at the minimum ambient temperature and
the maximum load expected.
Output capacitors can be increased in size to any desired
value above the minimum. One possible purpose of this
would be to maintain the output voltages during brief condi-
tions of negative input transients that might be characteristic
of a particular system.
Capacitors must also be rated at all ambient temperatures
expected in the system. Many aluminum type electrolytics
will freeze at temperatures less than −30˚C, reducing their
11 www.national.com

11 Page







PáginasTotal 16 Páginas
PDF Descargar[ Datasheet LM2984.PDF ]




Hoja de datos destacado

Número de piezaDescripciónFabricantes
LM2984Microprocessor Power Supply SystemNational Semiconductor
National Semiconductor
LM2984CLM2984C Microprocessor Power Supply SystemNational Semiconductor
National Semiconductor
LM2984CLM2984C Microprocessor Power Supply SystemTexas Instruments
Texas Instruments
LM2984CTLM2984C Microprocessor Power Supply SystemNational Semiconductor
National Semiconductor

Número de piezaDescripciónFabricantes
SLA6805M

High Voltage 3 phase Motor Driver IC.

Sanken
Sanken
SDC1742

12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters.

Analog Devices
Analog Devices


DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares,
permitiéndote verlos en linea o descargarlos en PDF.


DataSheet.es    |   2020   |  Privacy Policy  |  Contacto  |  Buscar