MAX8540EEE+ Maxim Integrated Products, MAX8540EEE+ Datasheet - Page 8

• Manufacturer Part Number: MAX8540EEE+
• Description: IC PWM CTRLR CURR-MODE 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX8540EEE+

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 1MHz
• Duty Cycle: 82%
• Voltage - Supply: 7.6 V ~ 18 V
• Buck: No
• Boost: No
• Flyback: Yes
• Inverting: No
• Doubler: No
• Divider: Yes
• Cuk: No
• Isolated: Yes
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 16-QSOP
• Frequency-max: 1MHz
• Duty Cycle (max): 80 %
• Mounting Style: SMD/SMT
• Switching Frequency: 200 KHz to 1000 KHz
• Maximum Operating Temperature: + 85 C
• Fall Time: 53 ns
• Minimum Operating Temperature: - 40 C
• Rise Time: 57 ns
• Synchronous Pin: Yes
• Topology: Flyback, Forward
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Synchronizable, High-Frequency Current- and
Voltage-Mode PWM Controllers for Isolated Supplies
8
MAX8540 MAX8541
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10
11
12
13
14
15
16
—
1
2
3
4
5
6
7
8
9
PIN
—
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
MAXDTY
SKTOFF
SCOMP
PRAMP
SKTON
NAME
FREQ/
OPTO
SYNC
GND
DRV
ILIM
V
REF
OV
UV
EN
CS
SS
CC
5V Reference Voltage Output. Bypass to ground with a 1µF capacitor. REF is pulled to GND
during shutdown.
System Input Overvoltage Monitoring. The OV threshold is 3.021V with 130mV hysteresis.
Connect to the center of a resistor-divider from the system input to GND to set the overvoltage
trip point (see the Overvoltage Threshold section).
System Input Undervoltage Monitoring and Feed-Forward Input. The UV threshold is 1.25V with
120mV hysteresis. Connect to the center of a resistor-divider from the system input to GND to
set the undervoltage trip point (see the Undervoltage Threshold section). This input can be used
as a disable input by pulling it below 1.2V. UV remains active during shutdown.
P r og r am m ab l e Fr eq uency and S ync Inp ut. C onnect a r esi stor i n p ar al l el w i th RC ( 10kΩ , 0.01µF) fr om
FRE Q/S Y N C to GN D to set the sw i tchi ng fr eq uency or ap p l y an exter nal cl ock si g nal thr oug h a d i od e
to synchr oni ze to an exter nal fr eq uency.
S oft- S tar t C ap aci tor C onnecti on. C onnect a cap aci tor fr om S S to GN D to set the soft- star t ti m e p er i od .
Programmable Maximum Duty-Cycle Input. Connect a resistor from MAXDTY to GND to set the
maximum duty cycle for minimum system input voltages. The maximum duty cycle is inversely
proportional to the system input voltage. The higher the input voltage, the less the maximum
duty cycle. The maximum duty cycle is internally limited to 80% at any switching frequency.
MAXDTY is high impedance during shutdown. Bypass MAXDTY with a 2200pF capacitor.
Active-Low Enable Input. Drive EN to GND to enable the IC. Drive high to place the IC in
shutdown mode.
Programmable Slope Compensation Input. Connect a resistor from SCOMP to GND to set the
slope compensation.
Programmable Voltage-Mode Control-Ramp Input. Connect a resistor from PRAMP to GND to
set the magnitude of the voltage ramp.
Isol ated Feed b ack Inp ut. C onnect to an op tocoup l er for an i sol ated p ow er conver ter or connect to the
outp ut of a vol tag e- er r or am p l i fi er for a noni sol ated p ow er conver ter for a feed b ack- er r or si g nal .
Current-Limit Threshold Input. Connect to the center of a resistor-divider from REF to GND to set
the current-limit threshold voltage.
C ur r ent- Li m i t O ff- Ti m e Inp ut. C onnect a cap aci tor fr om S KTOFF to GN D to set the cur r ent- l i m i t off- ti m e.
P ul l S KTO FF to RE F thr oug h a 10kΩ r esi stor to l atch off the IC after an over cur r ent event.
Current-Sense Input. Provides current-sense feedback for cycle-by-cycle current limit and is
also the current-mode input for the MAX8540. Connect a current-sense resistor from CS to GND.
Current-Limit On-Time Input. Connect a capacitor to ground to set the current-limit on-time.
Ground
Gate Drive for External N-Channel Power MOSFET. Connect to the gate of an external MOSFET
for low-power applications. Connect to the input of an external gate driver for high-power
applications.
Voltage Supply for the IC. Operating input voltage range is 7.6V to 18V. Bypass V
ceramic capacitor to GND.
FUNCTION
Pin Description
CC
with a