Datenblatt-Suchmaschine für elektronische Bauteile |
|
CS8129YT5G Datenblatt(PDF) 6 Page - ON Semiconductor |
|
CS8129YT5G Datenblatt(HTML) 6 Page - ON Semiconductor |
6 / 11 page CS8129 http://onsemi.com 6 CIRCUIT DESCRIPTION The CS8129 RESET function has hysteresis on both the reset and delay comparators, a latching Delay capacitor discharge circuit, and operates down to 1.0 V. The RESET circuit output is an open collector type with ON and OFF parameters as specified. The RESET output NPN transistor is controlled by the two circuits described (see Block Diagram on page 2). Low Voltage Inhibit Circuit This circuit monitors output voltage, and when output voltage is below the specified minimum causes the RESET output transistor to be in the ON (saturation) state. When the output voltage is above the specified level, this circuit permits the RESET output transistor to go into the OFF state if allowed by the RESET Delay circuit. Reset Delay Circuit This circuit provides a programmable (by external capacitor) delay on the RESET output lead. The Delay lead provides source current to the external delay capacitor only when the “Low Voltage Inhibit” circuit indicates that output voltage is above VRT(ON). Otherwise, the Delay lead sinks current to ground (used to discharge the delay capacitor). The discharge current is latched ON when the output voltage is below VRT(OFF). The Delay capacitor is fully discharged anytime the output voltage falls out of regulation, even for a short period of time. This feature ensures that a controlled RESET pulse is generated following detection of an error condition. The circuit allows the RESET output transistor to go to the OFF (open) state only when the voltage on the Delay lead is higher than VDC(HI). Figure 13. Test & Application Circuit CIN* 100 nF Delay VOUT RRST COUT** 10 mF to 100 mF RESET CS8129 *CIN is required if regulator is far from the power source filter. **COUT is required for stability. VIN GND 4.7 k W Delay 0.1 mF The Delay time for the RESET function is calculated from the formula: Delay time + CDelay VDelay Threshold ICharge Delay time + CDelay(mF) 3.2 105 If CDelay = 0.1 mF, Delay time (ms) = 32 ms ±50%: i.e. 16 ms to 48 ms. The tolerance of the capacitor must be taken into account to calculate the total variation in the delay time. APPLICATION NOTES STABILITY CONSIDERATIONS The output or compensation capacitor helps determine three main characteristics of a linear regulator: start−up delay, load transient response and loop stability. The capacitor value and type should be based on cost, availability, size and temperature constraints. A tantalum or aluminum electrolytic capacitor is best, since a film or ceramic capacitor with almost zero ESR can cause instability. The aluminum electrolytic capacitor is the least expensive solution, but, if the circuit operates at low temperatures (−25 °C to −40°C), both the value and ESR of the capacitor will vary considerably. The capacitor manufacturers data sheet usually provides this information. The value for the output capacitor COUT shown in Figure 13 should work for most applications, however it is not necessarily the optimized solution. To determine an acceptable value for COUT for a particular application, start with a tantalum capacitor of the recommended value and work towards a less expensive alternative part. Step 1: Place the completed circuit with a tantalum capacitor of the recommended value in an environmental chamber at the lowest specified operating temperature and monitor the outputs with an oscilloscope. A decade box connected in series with the capacitor will simulate the higher ESR of an aluminum capacitor. Leave the decade box outside the chamber, the small resistance added by the longer leads is negligible. Step 2: With the input voltage at its maximum value, increase the load current slowly from zero to full load while observing the output for any oscillations. If no oscillations are observed, the capacitor is large enough to ensure a stable design under steady state conditions. 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 load conditions for the regulator at low temperature. Step 4: Maintain the worst case load conditions set in step 3 and vary the input voltage until the oscillations increase. This point represents the worst case input voltage conditions. Step 5: If the capacitor is adequate, repeat steps 3 and 4 with the next smaller valued capacitor. A smaller capacitor will usually cost less and occupy less board space. If the output oscillates within the range of expected operating conditions, repeat steps 3 and 4 with the next larger standard capacitor value. |
Ähnliche Teilenummer - CS8129YT5G |
|
Ähnliche Beschreibung - CS8129YT5G |
|
|
Link URL |
Privatsphäre und Datenschutz |
ALLDATASHEETDE.COM |
War ALLDATASHEET hilfreich? [ DONATE ] |
Über Alldatasheet | Werbung | Kontakt | Privatsphäre und Datenschutz | Linktausch | Hersteller All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |