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 (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 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.
The MIC1555/7 is available in the SOT-23-5 5-pin
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
Typical Application
+5V
MIC1555
13
Standby
Trigger
4
2
100µs
VS
TRG
GND
THR
5
+5V
MIC1557
Output
4
Enabled
Disabled
3
2
8kHz
5
OUT
1k
VS
CS
GND
OUT
Output
1k
T/T
1
0.1µF
0.1µF
Monostable (One-Shot)
IttyBitty is a registered trademark of Micrel, Inc.
Astable (Oscillator)
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
May 2010
M9999-052610-D
Micrel, Inc.
MIC1555/1557
Ordering Information
Part Number
Standard
MIC1555BM5
MIC1557BM5
Pb-Free
MIC1555YM5
MIC1557YM5
T10
T11
Marking
Standard
Pb-Free
T10
T11
Temperature Range
–40° to +85°C
–40° to +85°C
Package
5-Pin SOT-23
5-Pin SOT-23
Note:
Under bar ( __ ) may not be to scale.
Pin Configuration
OUT GND VS
3
2
1
CS GND T/T
3
2
1
T10
4
5
Part
Identification
4
T11
5
Part
Identification
TRG
THR
VS
OUT
MIC1555
5-Pin SOT-23 (M)
MIC1557
5-Pin SOT-23 (M)
Pin Description
Pin Number
MIC1555
Pin Number
MIC1557
Pin Name
Pin Name
1
2
4
2
3
VS
GND
CS
OUT
TRG
THR
Supply (Input): +2.7 to +18V supply.
Ground: Supply return.
Chip Select/Reset (Input): Active high at >2/3V
S
. Output off
when low at<1/3V
S
.
Output: CMOS totem-pole output.
Trigger (Input): Sets output high. Active low (at
≤
2/3V
S
nominal).
Threshold (Dominant Input): Sets output low. Active high (at
≥
2/3V
S
nominal).
Trigger/Threshold (Input): Internally connected to both
threshold and trigger functions. See TRG and THR.
3
4
5
5
1
T/T
May 2010
2
M9999-052610-D
Micrel, Inc.
MIC1555/1557
Absolute Maximum Ratings
Supply Voltage (V
S
)......................................................+22V
Threshold Voltage (V
THR
, V
T/T
). ....................................+22V
Trigger Voltage (V
TGR
, V
T/T
) ..........................................+22V
Lead Temperature (soldering, 10sec.)....................... 300°C
Maximum Storage Temperature ................................ 150°C
Operating Ratings
Supply voltage (V
S
) ....................................... +2.7V to +18V
Ambient Temperature (T
A
) .......................... –40°C to +85°C
Package Thermal Resistance
(θ
JA
) .................................................................220°C/W
(θ
JC
) .................................................................130°C/W
Electrical Characteristics
T
A
= 25°C,
bold
values indicate –40°C< T
A
< +85°C, unless noted.
Parameter
Condition
Min
Typ
Max
300
400
1161
Units
Supply current
Monostable Timing Accuracy
Monostable Drift over Temp
V
S
= 5V
V
S
= 15V
R
A
= 10k, C =0.1µF, V
S
= 5V
R
A
= 10k, C =0.1µF, V
S
= 5V
V
S
= 5V, –55
≤
T
A
≤
+125°C,
Note 1
V
S
= 10V, –55
≤
T
A
≤
+125°C,
Note 1
V
S
= 15V, –55
≤
T
A
≤
+125°C,
Note 1
858
240
350
2
100
150
200
0.5
2
1717
µA
µA
%
µs
ppm/°C
ppm/°C
ppm/°C
%/V
%
Monostable Drift over Supply
Astable Timing Accuracy
Maximum Astable Frequency
Astable Drift over Temp
V
S
= 5V to 15V,
Note 1
R
A
= R
B
= 10k, C = 0.1µF, V
S
= 5V
R
A
= R
B
= 10k, C = 0.1µF, V
S
= 5V
R
T
= 1k, C
T
= 47pF, V
S
= 8V
V
S
= 5V, –55
≤
T
A
≤
+125°C,
Note 1
V
S
= 10V, –55
≤
T
A
≤
+125°C,
Note 1
V
S
= 15V, –55
≤
T
A
≤
+125°C,
Note 1
2323
µs
MHz
ppm/°C
ppm/°C
ppm/°C
%/V
5
100
150
200
0.5
61
27
Astable Drift over Supply
Threshold Voltage
Trigger Voltage
Trigger Current
Threshold Current
Chip Select
Output Voltage Drop
V
S
= 5V to 15V,
Note 1
V
S
= 15V
V
S
= 15V
V
S
= 15V
V
S
= 15V
on > 2/3 V
S
off > 1/3 V
S
V
S
= 15V, I
SINK
= 20mA
V
S
= 5V, I
SINK
= 3.2mA
V
S
= 15V, I
SOURCE
= 20mA
V
S
= 5V, I
SOURCE
= 3.2mA
14.1
3.8
2.7
50
28
67
32
72
37
50
50
%/V
S
%/V
S
nA
nA
%/V
S
%/V
S
V
V
V
V
67
33
0.3
0.08
14.7
4.7
72
50
1.25
0.5
Supply Voltage
Output Rise Time
Output Fall Time
Note 1.
Not tested.
functional operation,
Note 1
R
L
= 10M, C
L
= 10pF, V
S
= 5V,
Note 1
R
L
= 10M, C
L
= 10pF, V
S
= 5V,
Note 1
18
V
ns
ns
15
15
General Note:
Devices are ESD protected, however handling precautions recommended.
May 2010
3
M9999-052610-D
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