CS8141 Cherry Semiconductor Corporation, CS8141 Datasheet

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CS8141

Manufacturer Part Number
CS8141
Description
5V, 500mA Linear Regulator with ENABLE, RESET , and Watchdog
Manufacturer
Cherry Semiconductor Corporation
Datasheet

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Rev. 2/23/99
The CS8140 is a 5V Watchdog
Regulator with protection circuitry and
three logic control functions that allow
a microprocessor to control its own
power supply. The CS8140 is designed
for use in automotive, switch mode
power supply post regulator, and bat-
tery powered systems.
Basic regulator performance character-
istics include a low noise, low drift, 5V
± 4% precision output voltage with low
dropout voltage (1.25V @ I
and low quiescent current (7mA @ I
= 500mA). On board short circuit, ther-
mal, and overvoltage protection make it
possible to use this regulator in particu-
larly harsh operating environments.
The Watchdog logic function monitors
an input signal (WDI) from the micro-
processor or other signal source. When
the signal frequency moves outside
externally programmable window lim-
its, a
(
(C
dow frequency limits as well as the
power on reset (POR) and
The
ENABLE
RESET
DELAY
WDI
Gnd
V IN
RESET
RESET
) programs the watchdog win-
). An external capacitor
function is activated by any
signal is generated
ENABLE,
5V, 500mA Linear Regulator with
Control Logic
Watchdog
Reference
ENABLE
RESET
& Bias
Delay
OUT
RESET
= 500mA)
Description
delay.
Block Diagram
OUT
Regulation
Overtemperature
Overvoltage
of three conditions: the watchdog sig-
nal moves outside of its preset limits;
the output voltage drops out of regula-
tion by more than 4.5%; or the IC is in
its power up sequence. The
nal is independent of V
down to V
In conjunction with the Watchdog, the
ENABLE function controls the regula-
torÕs power consumption. The CS8140Õs
output stage and its attendant circuitry
are enabled by setting the ENABLE
lead high. The regulator goes into sleep
mode (I
ENABLE lead goes low and the watch-
dog signal moves outside its preset
window limits. This unique combina-
tion of control functions in the CS8140
gives the microprocessor control over
its own power down sequence: i.e. it
gives the microprocessor the flexibility
to perform housekeeping functions
before it powers down.
The CS8141 has the same features as the
CS8140, except that the CS8141 only
responds to input signals (WDI) which
are below the preset watchdog frequen-
cy threshold.
RESET
CS8140/1
Undervoltage
Short Circuit
OUT
OUT
= 250µA) when the
= 1V.
1
IN
*
, and Watchdog
and reliable
*NOTE: shorted together
on 7 Lead TO-220
RESET
V OUT
Sense
RESET
Delay
sig-
2000 South County Trail, East Greenwich, RI 02818
Sense
Delay
V
WDI
OUT
NC
NC
NC
Tel: (401)885-3600 Fax: (401)885-5786
Cherry Semiconductor Corporation
14 Lead PDIP
Web Site: www.cherry-semi.com
1
5V ± 4%, 500mA Output
Voltage
µP Compatible Control
Functions
Low Dropout Voltage
(1.25V @ 500mA)
Low Quiescent Current
(7mA @ 500mA)
Low Noise, Low Drift
Low Current SLEEP Mode
(I
Fault Protection
Email: info@cherry-semi.com
Package Options
Q
24 Lead SOIC Wide
Watchdog
ENABLE
Thermal Shutdown
60V Peak Transient
Voltage
Sense
Short Circuit
Delay
RESET
= 250µA)
V
WDI
Gnd
OUT
NC
NC
NC
NC
NC
NC
NC
Features
1
A
RESET
ENABLE
V
Gnd
NC
NC
NC
IN
7 Lead TO-220
1
RESET
ENABLE
NC
V
Gnd
NC
NC
NC
NC
NC
NC
NC
IN
Tab (Gnd)
¨
Company
1 V
2 ENABLE
3
4 Gnd
5 Delay
6 WDI
7 V
RESET
IN
OUT

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CS8141 Summary of contents

Page 1

... The CS8141 has the same features as the CS8140, except that the CS8141 only responds to input signals (WDI) which are below the preset watchdog frequen- cy threshold ...

Page 2

Input Voltage Operating Range .................................................................................................................................................-0.5 to +26V Peak Transient Voltage (46V Load Dump @ 14V V Electrostatic Discharge (Human Body Model)...............................................................................................................................................4kV WDI Input Signal Range ...............................................................................................................................................-0.3 to +7V Internal Power Dissipation ..............................................................................................................................Internally limited Junction Temperature Range (TJ) .......................................................................................................................-40¡C to +150¡C ...

Page 3

... N/A 5 1,6-11,13-19,22 5-10 * The CS8141 uses a fused lead package. Leads 6-8 and 17-19 are fused together through the lead frame. These leads are electrically connected to IC ground and should be connected to system ground for a good thermal connection. Electrical Characteristics: continued TEST CONDITIONS ...

Page 4

V vs. V over 25ûC OUT IN LOAD 5 ENABLE IN 5.0 4 LOAD load 4 6.67W load 3 10W 3.0 load 2.5 2.0 1.5 1.0 ...

Page 5

Typical Performance Characteristics: continued Quiescent Current vs. V over ENABLE (V) IN Watchdog Frequency ...

Page 6

Dropout Voltage The input-output voltage differential at which the circuit ceases to regulate against further reduction in input volt- age. Measured when the output voltage has dropped 100mV from the nominal value obtained at 14V input, dropout voltage is dependent ...

Page 7

Figure 3: Timing Diagrams for Watchdog and ENABLE Functions 3a: V when Watchdog is held high and ENABLE = HIGH. OUT V IN ENABLE WDI 0V RESET 0V V OUT 0V 3b: V when Watchdog is held low and ENABLE ...

Page 8

... WDI(LOWER (3. WDI(UPPER (2. WDI(UPPER) DELAY For the CS8141 the lower limit is determined by the equa- tions in (a) above. The capacitor C also determines the frequency of the DELAY RESET signal and the POWER-ON- period. RESET Function The RESET function is activated when the Watchdog sig- ...

Page 9

... WDI(LOWER) FAIL 141 76 Figure 6: WDI signal for CDelay = 0.82µF using CS8141. Application Notes DELAY Energy conservation is another benefit of using a regulator with integrated microprocessor control features. Using the CS8140 or CS8141 as indicated in Figure 8, the micropro- cessor can control its own power down sequence. The momentary contact switch quickly charges C1 through R1 ...

Page 10

Battery 0.1mF (optional) Ignition 0.1mF *C1 is required if regulator is located far from the power source filter. **C2 required for stability ***R ² 80k½ Figure 7. Application Diagram 110K Figure 8. Applications diagram for CS8140. The ...

Page 11

Step 3: Increase the ESR of the capacitor from zero using the decade box and vary the load current until oscillations appear. Record the values of load current and ESR that cause the greatest oscillation. This represents the worst case ...

Page 12

... SO (tape & reel) CS8140YN14 14L PDIP CS8141YT7 7L TO-220 Straight CS8141YTVA7 7L TO-220 Vertical CS8141YTHA7 7L TO-220 Horizontal CS8141YDWF24 24L SO (internally fused leads) CS8141YDWFR24 24L SO (internally fused leads) (tape & reel) CS8141YN14 14L PDIP Rev. 2/23/99 Package Specification D Thermal Data English Min Max Min R 15 ...

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