MIC502YN Micrel Inc, MIC502YN Datasheet - Page 9

• Manufacturer Part Number: MIC502YN
• Description: IC MANAGEMENT FAN/THERMAL 8DIP
• Manufacturer: Micrel Inc

Specifications of MIC502YN

• Applications: Fan Controller
• Number Of Outputs: 1
• Current - Output: 10mA
• Voltage - Supply: 4 V ~ 13.2 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Operating Current: 1.5mA
• Operating Temperature Classification: Industrial
• Package Type: PDIP
• Operating Supply Voltage (min): 4V
• Operating Supply Voltage (max): 13.2V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Load: -
• Lead Free Status / Rohs Status: Compliant
• Other names: 576-1242

Functional Description
Oscillator
A capacitor connected to CF determines the frequency
of the internal time base which drives the state-machine
logic and determines the PWM frequency. This operating
frequency will be typically 30Hz to 60Hz. (C
30Hz.)
Pulse-Width Modulator
A triangle-wave generator and threshold detector
comprise the internal pulse-width modulator (PWM). The
PWM’s output duty-cycle is determined by the higher of
V
applied to the V
100% duty-cycle. Since at least one of the control
voltage inputs is generally from a thermistor-resistor
divider connected to V
will not be affected by changes in the supply voltage.
Driver Output
OUT is a complementary push-pull digital output with
asymmetric drive (approximately 10mA source, 1mA
sink, see “Electrical Characteristics”). It is optimized for
directly driving an NPN transistor switch in the fan’s
ground-return. See “Applications Information” for circuit
details.
Shutdown/Reset
Internal circuitry automatically performs a reset of the
MIC502 when power is applied. The MIC502 may be
shut down at anytime by forcing V
threshold. This is typically accomplished by connecting
the V
results in an immediate and asynchronous shutdown of
the MIC502. The OUT and /OTF pins will float while V
is below V
If V
is equivalent to a power-up condition: the state of /OTF
is cleared, a startup interval is triggered, and normal fan
operation begins.
Startup Interval
Any time the fan is started from the off state (power-on
or coming out of sleep mode or shutdown mode), the
PWM output is automatically forced high for a startup
interval of 64× t
complete, PWM operation will commence and the duty-
cycle of the output will be determined by the higher of
V
Overtemperature Fault Output
/OTF is an active-low, open-collector logic output. An
over-temperature condition will cause /OTF to be
asserted. An overtemperature condition is determined by
V
Micrel, Inc.
November 2006
T1
T1
T1
or V
or V
T1
exceeding the normal operating range of 30% to
T1
then rises above V
T2
T2
pin to open-drain or open-collector logic and
.
. A typical voltage range of 30% to 70% of V
IL
.
T1
PWM
and V
. Once the startup interval is
DD
IH
, the PWM out-put duty cycle
, a device reset occurs. Reset
T2
pins corresponds to 0% to
T1
below its V
F
= 0.1µF for
DD
T1
IL
9
70% of V
by design to always be higher than V
Sleep Mode
When V
capable of operating without fan cooling and the MIC502
enters sleep mode and discontinues fan operation. The
threshold where the MIC502 enters sleep mode is deter-
mined by V
disables sleep mode.
Once in sleep mode, all device functions cease (/OTF in-
active, PWM output off) unless V
V
hysteresis added to the sleep comparator which
prevents erratic operation around the V
point. The result is stable and predictable thermostatic
action: whenever possible the fan is shut down to reduce
energy consumption and acoustic noise, but will always
be activated if the system temperature rises.
If the device powers-up or exits its reset state, the fan
will not start unless V
System Operation
Power Up
WAKE
• A complete reset occurs when power is applied.
• OUT is off (low) and /OTF is inactive (high/floating).
• If V
• The startup interval begins. OUT will be on (high) for
• Following the startup interval, normal operation
64 clock cycles (64 × t
begins.
. (V
T1
T1
DD
WAKE
< V
and V
by > 7% of V
SLP
IL
NO
Figure 3. Power-Up Behavior
= V
, the MIC502 remains in shutdown.
. Connecting the V
T2
Reset Startup Timer;
OUT Held On (High)
SLP
D
Deassert /OTF;
OUT Off (Low)
Startup Interval
During Startup
(
fall below V
P OW E R ON
eassert OUT
OUT = Low)
V
V
Interval.
Finished
T1
T1
Y E S
T1
+ V
NO
NO
> V
?
?
?
< V
OT
or V
IL
HYST
DD
.
PWM
. Note that V
T2
Y E S
). V
Y E S
).
rises above V
SLP
HYST
OP E RA T I ON
Assert /OTF While
, the system is deemed
NO RMAL
T1
V
T1
PWM(max)
is a fixed amount of
> V
SLP
or V
OT
OT
pin to ground
M9999-112206
T2
is guaranteed
SLP
WAKE
.
rise above
operating
MIC502
.