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Preliminary
TS4268
180mA Ultra Low Dropout Voltage Regulator with Reset & Watchdog Function
SOP-8
Pin Definition: 1. Input 2. N/C 3. Reset Output 4. Ground 8. Output 7. Watchdog 6. Radj 5. Reset Delay
General Description
TS4268 is a low dropout voltage regulator. The maximum input voltage is 45 V. It can deliver an output current of at least 180mA. TS4268 is short circuit proof and features temperature protection that disables the circuit in the event of impermissibly high temperatures. The watchdog function is disabled as a function of the load, so that a controller is not interrupted during sleep mode by a watchdog reset.
Application Description
TS4268 regulates an input voltage in the range 5.5V ~ 45V. In the event of an output voltage Vout < VRT, a reset signal is generated. The wiring of the reset switching threshold input enables the value of VRT to be reduced. The reset delay time can be adjusted using an external capacitor. The integrated watchdog monitors the connected active controller. If there is no positive going edge at the watchdog input, the reset output is set to low. The reset delay capacitor provides a wide adjustment range for the pulse repetition time. The watchdog function is only activated if the load exceeds 8mA. This ensures that a microcontroller is not activated during power-down and the current drain is not increased.
Features
Output voltage tolerance < 2 % Very low current consumption Low-drop voltage Watchdog Settable reset threshold Over temperature protection Reverse polarity protection Short-circuit proof Suitable for use in automotive electronics Wide temperature range
Ordering Information
Part No.
TS4268CS50 RL
Package
SOP-8
Packing
2.5Kpcs/ 13" Reel
Pin Description
Pin No.
1 2 3 4 5 6 7 8
Symbol
IN N/C RO GND RD RADJ WI OUT
Pin Description
Input Voltage. block to ground directly with ceramic capacitor Not Connected Reset Output. the open collector output is connected to the 5V output via an integrated resistor of 30k Ground Reset Delay. connect a capacitor to ground for delay time adjustment. Reset Switching Threshold. for setting the switching threshold, output to ground with voltage divider. If this input is connected to ground, the reset is triggered at an output voltage of 4.5V. Watchdog Input. positive-edge-triggered input for monitoring a microcontroller. Output Voltage. block to ground with 22uF capacitor, ESR <3
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TS4268
180mA Ultra Low Dropout Voltage Regulator with Reset & Watchdog Function
Circuit Description
The control amplifier compares a reference voltage, which is kept highly accurate by resistance adjustment, to a voltage that is proportional to the output voltage and drives the base of the series transistor via a buffer. Saturation control as a function of the load current prevents any over-saturation of the power element. If the externally scaled down output voltage at the reset threshold input drops below 1.35V, the external reset delay capacitor is discharged by the reset generator. If the voltage on the capacitor reaches the lower threshold VST, a reset signal is generated on the reset output and not cancelled again until the upper threshold voltage is exceeded. If the reset threshold input is connected to GND, reset is triggered at an output voltage of 4.5V. A connected microcontroller is monitored by the watchdog logic. If pulses are missing, the rest output is set to low. The pulse sequence time can be set within a wide range with the reset delay capacitor. TS4268 is also incorporates a member of internal circuits for protection against: * Over load * Over temperature * Reverse polarity
Block Diagram
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TS4268
180mA Ultra Low Dropout Voltage Regulator with Reset & Watchdog Function
Absolute Maximum Ratings
Parameter Input Input voltage Input current Reset Output Voltage Current Reset Delay Voltage Current Watchdog Watchdog input Reset Input Reset threshold Output Output voltage Output current Ground Current Temperatures Junction temperature Storage temperature Tj Tstg -40 -50 150 150 C Iq -100 50 mA Vout Iout -0.3 7 Internally limited V VRT -0.3 7 V Vwi -0.3 7 V VRD IRD -0.3 7 Internally limited V Vres Ires -0.3 7 Internally limited V Vin Iin -30 45 Internally limited V Symbol min. max. Unit Notes
Operation Range
Parameter Input voltage Junction temperature Symbol Vin Tj min. --40 max. 45 150 Unit C Notes
Thermal Resistance
Parameter Junction to ambient (soldered) Junction pin Symbol Rja Rjp min. --max. 185 72 Unit C/W (note 1) (note 2) Notes
1. Package mounted on PCB 80 x 80 x 1.5mm3, footprint only, zero airflow. 2. Measure to pin 2 Operation at up to the maximum junction temperature of 150C is possible in principle. Note, however, operation at the maximum permitted rating could be affected the reliability of the device.
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Preliminary
TS4268
180mA Ultra Low Dropout Voltage Regulator with Reset & Watchdog Function
Electrical Characteristics
(Vin=13.5V, -40 Tj 125 C, unless otherwise specified.)
o
Parameter
Output Voltage Current Limit Quiescent Current Dropout Voltage (note 1) Line Regulation Load Regulation Reset Function Reset threshold Reset adjust threshold Reset low voltage Saturation voltage Charging current Upper reset timing threshold Reset delay time Reset reaction time Pull-up Lower reset timing threshold Watchdog Input Discharge current Charging current Upper timing threshold Lower timing threshold Watchdog periode Watchdog trigger time Activating current Slew rate VRD < 1.0V VRD < 1.0V Vout= 0 Iq= 0mA Iq= 100mA IL=150mA
Test Conditions
5mA IL 150mA, 6V Vin 28V
Min
4.90 180 -----4.20 1.28
Typ
5.00 250 300 13 250 10 10 4.50 1.35 0.20 0.03 12 1.8 15 2 30 0.40 3.5 12 1.8 0.40 55 40 8 --
Max
5.10 -400 20 500 30 30 4.80 1.45 0.50 0.10 18 2.2 25 -46 0.55 5.2 18 2.2 0.55 75 60 15 --
Unit
V mA uA mA mV mV mV V V V V uA V mS uS K V uA uA V V mS mS mA V/us
6V Vin 28V, IL=150mA 5mA IL 150mA
1mA external Vout < VRT VRD < 1.0V CRD = 100nF CRD = 100nF With resp. to Vout
--5 1.4 10 -18 0.20 1.5 5 1.4 0.20
CRD = 100nF CRD = 100nF Activates watchdog from 20% up to 80% Vout
30 25 2 5
Note 1: Drop voltage = Vin - Vout (measured when the output voltage has dropped 100 mV from the nominal value obtained at 13.5 V input) Note 2: The reset output is low in range from Vout = 1V to Vout,rt.
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TS4268
180mA Ultra Low Dropout Voltage Regulator with Reset & Watchdog Function
Test Circuit
Reset Timing
The power-on reset delay time is defined by charging time of an external capacitor CD which can be calculated as follow:
CD = ( trd x ID,C ) / V
Definitions:
CD = delay capacitor trd = delay time ID,C = charge current, typical 12uA V = VDU, typical 1.8 V VDU = upper delay switching threshold at CD for reset delay time
The reset reaction time trr is the time it takes the voltage regulator to set the reset out LOW after the output voltage has dropped below the reset threshold. It is typically 1uS for delay capacitor of 47nF. For other values for C D the reaction time can be estimated using the following equation: Trr 20 s/F x CD
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TS4268
180mA Ultra Low Dropout Voltage Regulator with Reset & Watchdog Function
Timing (Watchdog Disabled)
Timing of the Watchdog Function
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TS4268
180mA Ultra Low Dropout Voltage Regulator with Reset & Watchdog Function
Notice
Specifications of the products displayed herein are subject to change without notice. TSC or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies. Information contained herein is intended to provide a product description only. No license, express or implied, to any intellectual property rights is granted by this document. Except as provided in TSC's terms and conditions of sale for such products, TSC assumes no liability whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of TSC products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right. The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications. Customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify TSC for any damages resulting from such improper use or sale.
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