LM3488MM National Semiconductor, LM3488MM Datasheet - Page 10
![IC, N-CH CONTROLLER, MSOP-8](/photos/18/97/189768/3778330_sml.jpg)
LM3488MM
Manufacturer Part Number
LM3488MM
Description
IC, N-CH CONTROLLER, MSOP-8
Manufacturer
National Semiconductor
Datasheet
1.LM3488MM.pdf
(24 pages)
Specifications of LM3488MM
Primary Input Voltage
40V
No. Of Outputs
1
Output Current
1A
No. Of Pins
8
Operating Temperature Range
-40°C To +125°C
Termination Type
SMD
Input Voltage Primary Min
2.95V
Output Voltage Min
1.26V
Rohs Compliant
No
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
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LM3488MM
Manufacturer:
NS/国半
Quantity:
20 000
Company:
Part Number:
LM3488MM/NOPB
Manufacturer:
TI
Quantity:
15 540
Part Number:
LM3488MMX
Manufacturer:
NS/国半
Quantity:
20 000
Company:
Part Number:
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Manufacturer:
ATMEL
Quantity:
3 410
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SLOPE COMPENSATION RAMP
The LM3488 uses a current mode control scheme. The main
advantages of current mode control are inherent cycle-by-cy-
cle current limit for the switch, and simpler control loop char-
acteristics. It is also easy to parallel power stages using
current mode control since as current sharing is automatic.
Current mode control has an inherent instability for duty cy-
cles greater than 50%, as shown in
small increase in the load current causes the switch current
to increase by ΔI
O
. The effect of this load change, ΔI
FIGURE 1. Basic Operation of the PWM comparator
Figure
FIGURE 2. Sub-Harmonic Oscillation for D>0.5
2. In
Figure
1
, is :
2, a
10
From the above equation, when D > 0.5, ΔI
than ΔI
very small perturbation in the load will cause the disturbance
to increase.
To prevent the sub-harmonic oscillations, a compensation
ramp is added to the control signal, as shown in
With the compensation ramp,
O
. In other words, the disturbance is divergent. So a
1
10138809
will be greater
Figure
10138807
3.