ASM8I1843F-08-MX ALSC [Alliance Semiconductor Corporation], ASM8I1843F-08-MX Datasheet - Page 3

• Manufacturer Part Number: ASM8I1843F-08-MX
• Description: Voltage Mode PWM Controller with EMI Reduction
• Manufacturer: ALSC [Alliance Semiconductor Corporation]

June 2005
rev 0.6
Application Information
Spread Spectrum Deviation
The deviation can be determined by selecting the proper
resistor at V
“R
selection)
PWM Frequency
The PWM frequency can be determined by selecting the
proper capacitance (C
Start-up Current
ASM8P18xx allows a substantial reduction in the start up
current. Low start up current allows high resistance, lower
wattage start-up resistor, to supply controller start up
power.
Under Voltage Lockout (UVLO)
When the power supply voltage is below the start up
threshold voltage, internal circuitry puts the output into low
impedance state and sets the output to zero.
Absolute Maximum Ratings
*Maximum output voltage = 30V
V
I
I
I
V
V
V
DD
OUT
SNS
D
DD
REF
OSC
OUT
Symbol
Resistor Vs. % Modulation Depth Plot” for resistor
REF
to GND for the parts with ‘ER’ suffix. (Refer
Supply Voltage
Supply Current
Maximum Output Current
Current Sense Inputs and feedback
Reference Voltage
Oscillator Voltage
Output Voltage
Operation Junction Temperature
Storage Temperature
Lead Soldering Temperature (10 Seconds)
Static Discharge Voltage MIL-STD-883
T
) at the FSEL pin.
Voltage Mode PWM Controller with EMI Reduction
Notice: The information in this document is subject to change without notice.
Parameter
I
SNS,
FB, COMP
Thermal Shutdown
The output of ASM8P18xx goes down to zero when the
junction temperature of the device rises above 155°C. The
device automatically resumes operation when temperature
drops to 126°C. This protects the device from thermal
breakdown.
Overload and under current protection
ASM8P18xx provides Cycle by cycle current limit and pulls
down PWM output to low as soon as I
peak voltage of 1V, with a delay to output of 125 nS
maximum.
At no load condition when the device senses the peak
voltage level of less than 0.1V at I
200mS, the oscillator enters in to cycle skip mode. Normal
condition is restored once I
more than three cycles. Details of cycle skip for different
options are provided in the Electrical Characteristics table.
ASM8P18S44ER / ASM8P18S45ER
ASM8P18S42 / ASM8P18S42ER
ASM8P1843 / ASM8P18S43ER
Min
-45
-65
SNS
increases beyond 0.1V for
TBD*
Max
150
150
300
30
30
1
5
6
4
2
SNS
pin for a period of
SNS
3 of 11
pin senses a
Units
mA
KV
°C
°C
°C
V
A
V
V
V
V