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 open-
collector discharge (D) pin. The threshold pin (THR) has
precedence over the trigger (TRG) input, ensuring that the
BiCMOS output is off when TRG is high.
The MIC1555 can 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 micro-
seconds 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 shut-
down. 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 and is rated for –40°C to +85°C ambient
temperature range. The MIC1555/7 is available in SOT-23-
5, and thin SOT23-5 5-pin packages. A low profile, ultra-
thin, (UTDFN), version of the MIC1555 (with chip select) is
also available.
Datasheets and support documentation are available on
Micrel’s web site at:
www.micrel.com.
®
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
•
10-pin ultra-thin DFN package (2mm × 2mm × 0.4mm)
•
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
IttyBitty is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
March 11, 2014
Revision 6.0
Micrel, Inc.
MIC1555/1557
Pin Configuration (MIC1555 UTDFN)
10-Pin UTDFN (MU)
(Top View)
Pin Description (MIC1555 UTDFN)
Pin Number
1
2
3, 4, 7, 9
5
6
8
10
Pin Name
VS
CS
NC
THR
TRG
GND
OUT
Pin Function
Supply (Input): +2.7 to +18V supply.
Chip Select/Reset (Input): Active high at >2/3V
S
. Output off when low at <1/3V
S
. If chip select
functionality is not desired, CS may be connected directly to VS.
No Connect. This pin is not internally connected.
Threshold (Dominant Input): Sets output low. Active high (at ≥ 2/3V
S
nominal).
Trigger (Input): Sets output high. Active low (at ≤2/3V
S
nominal).
Ground: Supply return.
Output: CMOS totem-pole output.
Pin Configuration (MIC1557 SOT-23 and TSOT-23)
5-Pin SOT-23 (M5)
(Top View)
5-Pin TSOT-23 (D5)
(Top View)
Pin Description (MIC1557 SOT-23 and TSOT-23)
Pin Number
1
2
3
4
5
Pin Name
T/T
GND
CS
VS
OUT
Pin Function
Trigger/Threshold (Input): Internally connected to both threshold and trigger functions. When the
voltage at this pin is ≤2/3VS it will set the output high. When the voltage at this pin is ≥2/3VS it will set
the output low.
Ground: Supply return.
Chip Select/Reset (Input): Active high at >2/3V
S
. Output off when low at <1/3V
S
. If chip select
functionality is not desired, CS may be connected directly to VS.
Supply (Input): +2.7 to +18V supply.
Output: CMOS totem-pole output.
March 11, 2014
4
Revision 6.0
Micrel, Inc.
MIC1555/1557
Absolute Maximum Ratings
(3,
5)
Supply Voltage (V
S
) ...................................................... +22V
Threshold Voltage (V
THR
, V
T/T
). .................................... +22V
Trigger Voltage (V
TGR
, V
T/T
) .......................................... +22V
Lead Temperature (soldering, 10s) ............................ 300°C
Maximum Storage Temperature ................................ 150°C
Operating Ratings
(4)
Supply voltage (V
S
) ....................................... +2.7V to +18V
Ambient Temperature (T
A
) .......................... –40°C to +85°C
Package Thermal Resistance
SOT23-5 and Thin SOT23-5 (θ
JA
) ................... 250°C/W
2mm × 2mm UTDFN (θ
JA
) ................................. 90°C/W
Electrical Characteristics
T
A
= 25°C,
bold
values indicate –40°C ≤ T
A
≤ +85°C, unless noted.
Parameter
Supply Current
Condition
V
S
= 5V
V
S
= 15V
R
A
= 10kΩ, C =0.1µF, V
S
= 5V
R
A
= 10kΩ, C =0.1µF, V
S
= 5V
V
S
= 5V, –55°C ≤ T
A
≤ +125°C
Monostable Drift
Overtemperature
Monostable Drift over Supply
Astable Timing Accuracy
Maximum Astable
Frequency
Astable Drift
Overtemperature
Astable Drift over Supply
Threshold Voltage
Trigger Voltage
Trigger Current
Threshold Current
Chip Select
Notes:
3. Exceeding the absolute maximum ratings may damage the device
4. The device is not guaranteed to function outside its operating ratings.
5. Devices are ESD protected, however handling precautions recommended.
6. Not tested.
(6)
(6)
(6)
Min.
Typ.
240
350
2
Max.
300
400
Units
µA
%
Monostable Timing Accuracy
858
100
150
200
0.5
2
1717
5
(6)
(6)
(6)
1161
µs
V
S
= 10V, –55°C ≤ T
A
≤ +125°C
V
S
= 15V, –55°C ≤ T
A
≤ +125°C
V
S
= 5V to 15V
(6)
ppm/°C
%/V
%
2323
µs
MHz
R
A
= R
B
= 10kΩ, C = 0.1µF, V
S
= 5V
R
A
= R
B
= 10kΩ, C = 0.1µF, V
S
= 5V
R
T
= 1kΩ, C
T
= 47pF, V
S
= 8V
V
S
= 5V, –55°C ≤ T
A
≤ +125°C
100
150
200
0.5
61
27
67
32
72
37
50
50
50
28
67
33
72
50
%/V
%/V
S
%/V
S
nA
nA
%/V
S
ppm/°C
V
S
= 10V, –55°C ≤ T
A
≤ +125°C
V
S
= 15V, –55°C ≤ T
A
≤ +125°C
V
S
= 5V to 15V
V
S
= 15V
V
S
= 15V
V
S
= 15V
V
S
= 15V
on > 2/3 V
S
off < 1/3 V
S
(6)
March 11, 2014
5
Revision 6.0
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