MICREL MIC1555BM5, MIC1557BM5 Datasheet
MIC1555/1557 Micrel
8kHz
Enabled
Disabled
VS
CS
MIC1557
4
3
GND
2
+5V
OUT
5
T/T
1
Output
1k
0.1µF
MIC1555/1557
IttyBitty™ RC Timer / Oscillator
General Description
The MIC1555 IttyBitty™ CMOS RC timer/oscillator and
MIC1557 IttyBitty CMOS RC oscillator are designed to provide rail-to-rail pulses for precise time delay or frequency
generation.
The devices are similar in function to the industry standard
“555”, without a frequency control (FC) pin or an opencollector discharge (D) pin. The threshold pin (TH) has
precedence over the trigger (TR) input, ensuring that the
BiCMOS output is off when TR is high.
The MIC1555 may be used as an astable (oscillator) or
monostable (one-shot) with separate threshold and trigger
inputs. In the one-shot mode, the output pulse width is
precisely controlled by an external resistor and a capacitor.
Time delays may be accurately controlled from microseconds to hours. In the oscillator mode, the output is used to
provide precise feedback, with a minimum of one resistor and
one capacitor producing a 50% duty cycle square wave.
The MIC1557 is designed for astable (oscillator) operation
only, with a chip select/reset (CS) input for low power shutdown. One resistor and one capacitor provide a 50% duty
cycle square wave. Other duty-cycle ratios may be produced
using two diodes and two resistors.
The MIC1555/7 is powered from a +2.7V to +18V supply
voltage.
The MIC1555/7 is available in the SOT-23-5 5-lead package,
and is rated for –40°C to +85°C ambient temperature range.
Features
• +2.7V to +18V operation
• Low current
<1µA typical shutdown mode (MIC1557)
200µA typical (TRG and THR low) at 3V supply
• Timing from microseconds to hours
• “Zero” leakage trigger and threshold inputs
• 50% square wave with one Resistor, one Capacitor
• Threshold input precedence over trigger input
• <15Ω output on resistance
• No output cross-conduction current spikes
• <0.005%/°C temperature stability
• <0.055%/V supply stability
• Small SOT-23-5 surface mount package
Applications
• Precision timer
• Pulse generation
• Sequential timing
• Time-delay generation
• Missing pulse detector
• Micropower oscillator to 5MHz
• Charge-pump driver
• LED blinker
• Voltage converter
• Linear sweep generator
• Variable frequency and duty cycle oscillator
• Isolated feedback for power supplies
Ordering Information
Part Number Temp. Range Package Marking
MIC1555BM5 –40°C to +85°C SOT-23-5 T10
MIC1557BM5 –40°C to +85°C SOT-23-5 T11
Typical Applications
+5V
MIC1555
13
VS OUT
Standby
Trigger
October 1998 1 MIC1555/1557
4
TRG
GND2THR
Monostable (One-Shot)
100µs
Output
1k
5
0.1µF
Astable (Oscillator)
MIC1555/1557 Micrel
Pin Configuration
VS
GND GND
13
22
CS
T10
45
THRTRG
T11
T/T
13
Part
Identification
OUTVS
Part Number Identification
MIC1555BM5 T10
OUT
45
MIC1557BM5 T11
SOT-23-5 (M5)
Pin Description
Pin Number Pin Number Pin Name Pin Function
MIC1555 MIC1557
1 4 VS Supply (Input): +2.7 to +18V supply.
2 2 GND Ground: Supply return.
>2
3 CS Chip Select/Reset (Input): Active high at
<1⁄3VS.
3 5 OUT Output: CMOS totem-pole output.
4 TRG Trigger (Input): Sets output high. Active low (at ≤ 2⁄3VS nominal)
5 THR Threshold (Dominant Input): Sets output low. Active high (at ≥ 2⁄3V
nominal).
1 T/T Trigger/Threshold (Input): Internally connected to both threshold and trigger
functions. See TRG and THR.
⁄3VS. Output off when low at
.
S
MIC1555/1557 2 October 1998
MIC1555/1557 Micrel
Absolute Maximum Ratings
Supply Voltage (VS) ....................................................+22V
Threshold Voltage (V
Trigger Voltage (V
Lead Temperature (soldering 10sec.) ....................... 300°C
TRG
, V
THR
, V
) ..................................+22V
T/T
) .......................................+22V
T/T
Operating Ratings
Supply Voltage (VS) ..................................... +2.7V to +18V
Ambient Temperature Range (TA) ............. –40°C to +85°C
Package Thermal Resistance
(θJA)...................................................................220°C/W
(θJC) ..................................................................130°C/W
Electrical Characteristics
TA = 25°C, bold values indicate –40°C ≤ TA ≤ +85°C; unless noted.
Parameter Condition Min Typ Max Units
Supply current VS = 5V 240 300 µA
VS = 15V 350 400 µA
Monostable Timing Accuracy RA = 10k, C =0.1µF, VS = 5V 2 %
RA = 10k, C =0.1µF, VS = 5V 858 1161 µs
Monostable Drift over Temp VS = 5V, –55 ≤ TA ≤ +125°C, Note 1 100 ppm/°C
VS =10V, –55 ≤ TA ≤ +125°C, Note 1 150 ppm/°C
VS = 15V, –55 ≤ TA ≤ +125°C, Note 1 200 ppm/°C
Monostable Drift over Supply VS = 5V to 15V, Note 1 0.5 %/V
Astable Timing Accuracy RA = RB = 10k, C = 0.1µF, VS = 5V 2 %
RA = RB = 10k, C = 0.1µF, VS = 5V 1717 2323 µs
Maximum Astable Frequency RT = 1k, CT = 47pF, Vs = 8V 5 MHz
Astable Drift over Temp VS = 5V, –55 ≤ TA ≤ +125°C, Note 1 100 ppm/°C
VS =10V, –55 ≤ TA ≤ +125°C, Note 1 150 ppm/°C
VS = 15V, –55 ≤ TA ≤ +125°C, Note 1 200 ppm/°C
Astable Drift over Supply VS = 5V to 15V, Note 1 0.5 %/V
Threshold Voltage VS = 15V 61 67 72 %V
Trigger Voltage VS = 15V 27 32 37 %V
Trigger Current VS = 15V 50 nA
Threshold Current VS = 15V 50 nA
Chip Select on > 2/3V
off < 1/3V
Output Voltage Drop VS = 15V, I
VS = 5V, I
Output Voltage Drop VS = 15V, I
VS = 5V, I
Supply Voltage functional operation, Note 1 2.7 18 V
Output Rise Time RL = 10M, CL = 10pF, VS = 5V, Note 1 15 ns
Output Fall Time RL = 10M, CL = 10pF, VS = 5V, Note 1 15 ns
S
S
= 20mA 0.3 1.25 V
SINK
= 3.2mA 0.08 0.5 V
SINK
SOURCE
SOURCE
= 20mA 14.1 14.7 V
= 3.2mA 3.8 4.7 V
50 67 72 %V
28 33 50 %V
S
S
S
S
General Note: Devices are ESD protected, however handling precautions are recommended.
Note 1: Not tested.
October 1998 3 MIC1555/1557
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