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PDF CS8151YDWFR16 Data sheet ( Hoja de datos )
| Número de pieza | CS8151YDWFR16 | |
| Descripción | 5V/ 100mA Low Dropout Linear Regulator with WATCHDOG/ RESET/ & WAKE UP | |
| Fabricantes | Cherry Semiconductor Corporation | |
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CS8151
5V, 100mA Low Dropout Linear Regulator
with WATCHDOG, RESET, & WAKE UP
Description
The CS8151 is a precision 5V, 100mA
micro-power voltage regulator with
very low quiescent current (400µA
typical at 200µA load). The 5V output
is accurate within ±2% and supplies
100 mA of load current with a typical
dropout voltage of 400mV.
Microprocessor control logic includes
Watchdog, Wake Up and RESET . This
unique combination of low quiescent
current and full microprocessor con-
trol makes the CS8151 ideal for use in
battery operated, microprocessor con-
trolled equipment.
The CS8151 WAKE UP function brings
the microprocessor out of Sleep mode.
The microprocessor in turn, signals its
WAKE UP status back to the CS8151
by issuing a WATCHDOG signal.
The WATCHDOG logic function mon-
itors an input signal (WDI) from the
microprocessor. The CS8151 responds
to the falling edge of the WATCH-
DOG signal which it expects at least
once during each wake-up period.
When the correct WATCHDOG signal
is received, a falling edge is issued on
the wake-up signal line.
RESET is independent of VIN and
operates correctly to an output voltage
as low as 1V. A RESET signal is issued
in any of three situations. During
power up the RESET is held low until
the output voltage is in regulation.
During operation if the output voltage
shifts below the regulation limits, the
RESET toggles low and remains low
until proper output voltage regulation
is restored. And finally, a RESET signal
is issued if the regulator does not
receive a WATCHDOG signal within
the WAKE UP period.
The RESET pulse width, WAKE UP
signal frequency, and WAKE UP delay
time are all set by one external capaci-
tor CDelay.
The regulator is protected against
short circuit, over voltage, and thermal
runaway conditions. The device can
withstand 74 volt load dump tran-
sients, making it suitable for use in
automotive environments.
Block Diagram
VIN
Current Source
(Circuit Bias)
Over
Voltage
Shutdown
Current Limit
Sense
VOUT
VOUT
internally
connected on
TO-220 and
D2PAK
WAKE UP
Features
s 5V ±2% / 100 mA Output
Voltage
s Micropower Compatible
Control Functions:
WAKE UP
WATCHDOG
RESET
s Low Dropout Voltage:
400mV @ 100mA
s Low Sleep Mode Quiescent
Current (400µA typ)
s Protection Features:
Thermal Shutdown
Short Circuit
74V Load Dump
Reverse Transient (-50V)
Package Options
16 Lead PDIP
16 Lead SOIC Wide*
(Internally Fused)
N/C 1
N/C
N/C
Gnd
Gnd
*N/C
Sense
VOUT
Delay
______
RESET
WAKE UP
Gnd
Gnd
WDI
N/C
VIN
* For SO Wide package, pin # 6 is Gnd
Delay
WDI
RESET
Timing
Circuit
WAKE UP
Circuit
Falling Edge
Detector
VOUT
WATCHDOG
Circuit
Thermal
Shutdown
+ - Error
Amplifier
Bandgap
Reference
RESET
Circuit
Rev. 5/4/99
7 Lead TO-220 7 Lead D2PAK
Sense
Tab (Gnd)
Tab (Gnd)
Gnd
1
1. VOUT
2. VIN
3. WDI
4. Gnd
1
5. WAKE UP
6. RESET
7. Delay
1
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: [email protected]
Web Site: www.cherry-semi.com
A ¨ Company
1 page  
Definition of Terms
Dropout Voltage:
The input-output voltage differential at which the cir-
cuit ceases to regulate against further reduction in
input voltage. Measured when the output voltage has
dropped 100mV from the nominal value obtained at
14V input, dropout voltage is dependent upon load
current and junction temperature.
Input Voltage:
The DC voltage applied to the input terminals with
respect to ground.
Line Regulation:
The change in output voltage for a change in the
input voltage. The measurement is made under con-
ditions of low dissipation or by using pulse tech-
niques such that the average chip temperature is not
significantly affected.
Load Regulation:
The change in output voltage for a change in load
current at constant chip temperature.
Quiescent Current:
The part of the positive input current that does not
contribute to the positive load current. The regulator
ground lead current.
Ripple Rejection:
The ratio of the peak-to-peak input ripple voltage to
the peak-to-peak output ripple voltage.
Current Limit:
Peak current that can be delivered to the output.
Circuit Description
Functional Description
To reduce the drain on the battery a system can go into a
low current consumption mode when ever its not per-
forming a main routine. The WAKE UP signal is generated
continuously and is used to interrupt a microcontroller
that is in sleep mode. The nominal output is a 5 volt
square wave with a duty cycle of 50% at a frequency that
is determined by a timing capacitor, CDelay.
When the microprocessor receives a rising edge from the
WAKE UP output, it must issue a watchdog pulse and
check its inputs to decide if it should resume normal oper-
ations or remain in the sleep mode.
The first falling edge of the watchdog signal causes the
WAKE UP to go low within 2µs (typ) and remain low until
the next WAKE UP cycle (see Figure 2). Other watchdog
pulses received within the same cycle are ignored (Figure
1).
During power up, RESET is held low until the output volt-
age is in regulation. During operation, if the output volt-
age shifts below the regulation limits, the RESET toggles
low and remains low until proper output voltage regula-
tion is restored. After the RESET delay, RESET returns
high.
The WATCHDOG circuitry continuously monitors the
input watchdog signal (WDI) from the microprocessor.
The absence of a falling edge on the WATCHDOG input
during one WAKE UP cycle will cause a RESET pulse to
occur at the end of the WAKE UP cycle. (see Figure 1b).
The WAKE UP output is pulled low during a RESET
regardless of the cause of the RESET . After the RESET
returns high, the WAKE UP cycle begins again (see
Figures 1b).
The RESET pulse width, WAKE UP signal frequency and
RESET high to WAKE UP delay time are all set by one
external capacitor CDelay.
WAKE UP period=(4x105)CDelay
RESET Delay Time=(5x104)CDelay
RESET HIGH to WAKE UP Delay Time =(2x105)CDelay
Capacitor temperature coefficient and tolerance as well as the
tolerance of the CS8151 must be taken into account in order
to get the correct system tolerance for each parameter.
WAKE UP
WDI
WAKE UP
Response to
WDI
Figure 2. WAKE UP response to WDI
______
RESET
WAKE UP
WAKE UP
Re_s_p_o_n_s_e to
RESET
Figure 3. WAKE UP response to RESET (Low Voltage)
5
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| PDF Descargar | [ Datasheet CS8151YDWFR16.PDF ] | |
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