SCT1555 ZETEX | Alldatasheet

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Technical content

These devices are precision timing circuits for generation of accurate time delays or oscillation. Advanced circuit design means that these devices can operate from a single battery cell with the minimum of quiescent current. In monostable mode time delays are controlled by a single resistor and capacitor network. In astable mode the frequency and duty cycle can be accurately and independently controlled with two external resistors and one capacitor. The threshold and trigger levels are normally set as a proportion of V CC by internal resistors. These levels can be programmed by the use of the control input pin. When the trigger input reduces to a value below the trigger level, the flip-flop is set and the output goes high. With the trigger input above the trigger level and the threshold input above the threshold level, the flip-flop is reset and the output goes low. The reset pin has priority over all the other inputs and is used to start new timing cycles. A low on the reset input causes the flip-flop to reset forcing the output low. Whenever the output is forced low then the internal discharge transistor is turned on.

FEATURES

  • 0.9V supply operating voltage guaranteed
  • Pin connections comparable with 555 series timers
  • Very low quiescent current 74 µA
  • SO8 and DIL8 packages
  • Operating temperature range compatible with battery technologies

APPLICATIONS

  • Portable and battery powered equipment
  • Low voltage and low power systems PRECISION SINGLE CELL TIMER ISSUE 2 - MAY 1998 ZSCT1555 DISCHARGE THRESH TRIGGER CONTROL VCC RESET OUTPUT GND SCHEMATIC DIAGRAM 4-311

(Cont, Reset, Thres, Trig) Output Current 100mA Operating Temperature -20 to 100°C Storage Temperature -55 to 150°C Power Dissipation (T amb=25°C) DIL8 625mW SO8 625mW Recommended Operating Conditions Supply Voltage 0.9V(min) 6V(max) Input Voltages 6V(max) (Cont, Reset, Thres, Trig) Output Current Sink 100mA(max) S o u r c e 1 5 0 µA(max)

ELECTRICAL CHARACTERISTICS

TEST CONDITIONS (Unless otherwise stated):Tamb= 25°C,VCC= 1.5V SYMBOL PARAMETER CONDITIONS LIMITS UNITS MIN. TYP. MAX. VCC Supply Voltage 0.9 6 V ICC Supply Current no load VCC= 5V, no load 150 120 200 mA VTH Threshold Voltage VCC= 5V 1.195 3.9 1.22 1.245 4.1 V ITH Threshold Current (Note 1) 0 20 100 nA VTR Trigger Voltage VCC= 5V 0.2 0.57 0.25 0.62 0.3 0.67 V ITR Trigger Current 0 -35 -100 nA tPD Trigger Propagation delay Delay from trigger to output 2 µs VRS Reset Voltage 0.1 0.2 0.4 V IRS Reset Current Reset @ 0V 0 -5 -10 µA IDS Discharge switch Off-state current 0 10 100 nA VDS Discharge switch On-state voltage IDS= 0.2mA VCC= 5V, IDS= 0.3mA 180 240 225 350 mV VCT Control Voltage (Open Circuit) VCC= 5V 1.195 3.9 1.22 1.245 4.1 V VOL Output Voltage (Low) I OL=10mA IOL=50mA VCC=5V, IOL=10mA VCC=5V, IOL=100mA 0.15 0.45 0.13 0.65 0.3 0.65 0.3 V VOH Output Voltage (High) IOH= 100µA VCC= 5V, IOH= 150µA 4.5 1.1 4.6 1.5 V ZSCT1555 4-312

SYMBOL PARAMETER CONDITIONS LIMITS UNITS MIN. TYP. MAX. tR Output pulse rise time C L= 10pF VCC=5V, CL=10pF 1.6 1.2 µs tF Output pulse fall time C L= 10pF VCC=5V, CL=10pF 240 ns ΔtIA(m) ΔtV(m) ΔtT(m) Timing error, Monostable Initial accuracy (Note 2) Drift with supply voltage Drift with temperature RA= 10 to 50 kΩ RB= 10 to 50 kΩ C T = 68nF 1.6 0.262 100 %/V ppm/°C ΔtIA(a) ΔtV(a) ΔtT(a) Timing error, Astable Initial accuracy (Note 2) Drift with supply voltage Drift with temperature RA= 10 to 50 kΩ RB= 10 to 50 kΩ C T = 68nF 4.8 0.662 150 %/V ppm/°C fA Astable maximum frequency RA=20 kΩ RB= 10 kΩ CT =47pF 330 kHz Note 1: This will influence the maximum values of RA and RB (RAMAX=10MΩ ,RBMAX=1.5MΩ ) Note 2: Is defined as the difference between the measured value and the average value of a random sample taken on a batch basis ZSCT1555 ELECTRICAL CHARACTERISTICS (Continued) TEST CONDITIONS (Unless otherwise stated):Tamb=25°C,VCC=1.5V 4-313

0.80 0.85 0.90 0.95 1.00 1.05 Pulse Duration relative to Vcc=5v Supply Voltage (V) Normalized Output Pulse Duration v Supply Voltage -20°C +25°C +100°C 200 160 120 Supply Current (µA) Supply Voltage (V) Supply Current v Supply Voltage 00 . 2 Propagation Delay (µs) Lowest Voltage Level of Trigger Pulse (xVcc) Output Propagation Delay Vcc=5v 0.1 +100°C +25°C -20°C Rout/Vcc=1K 00 . 1 0 . 2 Propagation Delay (µs) Lowest Voltage Level of Trigger Pulse (xVcc) Output Propagation Delay Vcc=1.5v +25°C -20°C Rout/Vcc=1K 00 . 1 +100°C +25°C -20°C Minimum Pulse Width (µs) Lowest Voltage Level of Trigger Pulse (xVcc) Minimum Pulse Width Required for Triggering Vcc=1.5v Rout/Vcc = 1K 00 . 2 +100°C +25°C -20°C Minimum Pulse Width (µs) Lowest Voltage Level of Trigger Pulse (xVcc) Minimum Pulse Width Required for Triggering Vcc=5v 0.1 Rout/Vcc = 1K +100°C TYPICAL CHARACTERISTICS 4-314

Vcc=5v -20°C +25°C +100°C 10.10.010.001 Sink Current (mA) Discharge Transistor Voltage v Sink Current 0.1 0.01 Discharge Transistor Voltage (V) Vcc=1.5v -20°C +25°C +100°C 10.10.010.001 Sink Current (mA) Discharge Transistor Voltage v Sink Current 0.1 0.001 Discharge Transistor Voltage (V) 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.01 0.1 1 10 100 Low Level Output Current (mA) Output Low Voltage Drop v Output Current Low Level Output Voltage (V) Vcc=1.5v -20°C +25°C +100°C 1.0 0.8 0.6 0.4 0.2 0.0 0.01 0.1 1 10 100 Low Level Output Current (mA) Output Low Voltage Drop v Output Current Low Level Output Voltage (V) -20°C +25°C +100°C Vcc=5v 0.5 0.4 0.3 0.2 0.1 0.0 -20°C +25°C +100°C Vcc=5v Vcc - Vout (V) 0.001 0.01 0.1 1.0 High Level Output Current (mA) Output High Voltage Drop v Output Current 1.0 0.8 0.6 0.4 0.2 0.0 1.00.10.010.001 -20°C +25°C +100°C Vcc=1.5v High-Level Output Current (mA) Output High Voltage Drop v Output Current Vcc - Vout (V) TYPICAL CHARACTERISTICS 4-315

RESET TRIGGER VALUE THRESHOLD VOLTAGE OUTPUT DISCHARGE SWITCH Low N/A N/A Low On High <V CC/5 N/A High Off High >V CC/5 >4V CC/5 Low On High >V CC/5 <4V CC/5 As Previously established POWER DERATING TABLE Package TA≤25°C Power Rating Derating Factor Above TA=25°C TA=70°C Power Rating TA=85°C Power Rating N8 625mW 6.25mW/°C 330mW 250mW D8 625mW 6.25mW/°C 330mW 250mW ZSCT1555 4-316

The circuit of Figure 12 shows the device in astable mode operating as part of a single cell boost converter. This circuit generates a 5 volt supply from a single battery cell. The circuit output voltage is maintained down to 0.9 volts input and power economy is optimised for extended battery life. 4-320

ORDERING INFORMATION

Part Number Package Part Mark ZSCT1555D8 DIL8 ZSCT1555 ZSCT1555N8 SO8 ZSCT1555 CONNECTION DIAGRAM