MSL3088-IUR Atmel, MSL3088-IUR Datasheet - Page 21

• Manufacturer Part Number: MSL3088-IUR
• Description: LED Lighting Drivers 8-Str LED Driver Intrnl Bst Cntr/Phas
• Manufacturer: Atmel

Specifications of MSL3088-IUR

• Rohs: yes
• Input Voltage: 5 V
• Operating Frequency: 200 Hz
• Maximum Supply Current: 18 mA
• Output Current: 350 uA
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: VQFN-24
• Minimum Operating Temperature: - 40 C
• Power Dissipation: 1850 mW





Solving for C
Example:
As an example, set the maximum (un-optimized) output voltage to 39V, using voltage divider as follows:
R
R
Let the load current be 800mA maximum, use 10uH inductor, a 20F output capacitor, a 12V input voltage, a 12m R
and the switching frequency is 625kHz.
Set the crossover frequency to 1/5
Next calculate the compensation resistor value to achieve the 15kHz crossover frequency, or
Then calculate the compensation capacitor, C
3kHz
When laying out the circuit board, place the voltage divider resistors and compensation resistor/capacitors as close to t
MSL3086/88 as possible and minimize trace lengths connected to COMP and FB.
LED Dimming Control
E
Control MSL3086/87 LED brightness using Pulse Width Modulation (PWM) with a PWM signal applied to the external
Next determine the desired crossover frequency as 1/5th of the lower of the ESR zero f
switching frequency fSW. The crossover frequency equation is:
where f
the series RC compensation network. Rearranging the factors of this equation yields the solution for R
Solving for C
These equations are accurate if the compensation zero (formed by the compensation resistor R
C
compensation zero is 1/5th of the crossover frequency, or:
Solving for C
Example:
As an example, set the maximum (un-optimized) output voltage to 39V, using voltage divider as follows:
R
Example:
R
As an example, set the maximum (un-optimized) output voltage to 39V, using voltage divider as follows:
Let the load current be 800mA maximum, use 10uH inductor, a 20F output capacitor, a 12V input voltage, a 12m R
and the switching frequency is 625kHz.
Let the load current be 800mA maximum, use 10µH inductor, a 20µF output capacitor, a 12V input voltage, a 0.25Ω R
switching frequency is 625kHz.
Set the crossover frequency to 1/5
Set the crossover frequency to 1/5th f
Next calculate the compensation resistor value to achieve the 15kHz crossover frequency, or
Next calculate the compensation resistor value to achieve the 15kHz crossover frequency, or
Then calculate the compensation capacitor, C
Then calculate the compensation capacitor, C
3kHz
When laying out the circuit board, place the voltage divider resistors and compensation resistor/capacitors as close to the MSL3086/88
as possible and minimize trace lengths connected to COMP and FB.
When laying out the circuit board, place the voltage divider resistors and compensation resistor/capacitors as close to t
MSL3086/88 as possible and minimize trace lengths connected to COMP and FB.
LED Dimming Control
E
Control MSL3086/87 LED brightness using Pulse Width Modulation (PWM) with a PWM signal applied to the external
PWM input. The PWM dimming signals (outputs) take the frequency and duty cycle of the input signal but are staggere
in time so that they start at evenly spaced intervals relative to the PWM input signal. When one or more strings are
C
C
R
R
Set the crossover frequency to 1/5
R
Then calculate the compensation capacitor, C
C
Solving for C
C
Example:
As an example, set the maximum (un-optimized) output voltage to 39V, using voltage divider as follows:
R
Let the load current be 800mA maximum, use 10uH inductor, a 20F output capacitor, a 12V input voltage, a 12m R
and the switching frequency is 625kHz.
Next calculate the compensation resistor value to achieve the 15kHz crossover frequency, or
3kHz
When laying out the circuit board, place the voltage divider resistors and compensation resistor/capacitors as close to
MSL3086/88 as possible and minimize trace lengths connected to COMP and FB.
LED Dimming Control
E
Control MSL3086/87 LED brightness using Pulse Width Modulation (PWM) with a PWM signal applied to the external
PWM input. The PWM dimming signals (outputs) take the frequency and duty cycle of the input signal but are staggere
R
R
Next determine the desired crossover frequency as 1/5
or the switching frequency f
where f
the resistor of the series RC compensation network. Rearranging the factors of this equation yields the solution for R
as:
Solving for C
These equations are accurate if the compensation zero (formed by the compensation resistor R
compensation capacitor C
compensation capacitor such that the compensation zero is 1/5
Example:
As an example, set the maximum (un-optimized) output voltage to 39V, using voltage divider as follows:
R
©
R
Let the load current be 800mA maximum, use 10uH inductor, a 20F output capacitor, a 12V input voltage, a 12m R
and the switching frequency is 625kHz.
Set the crossover frequency to 1/5
f
Next calculate the compensation resistor value to achieve the 15kHz crossover frequency, or
f
Then calculate the compensation capacitor, C
3kHz
C
When laying out the circuit board, place the voltage divider resistors and compensation resistor/capacitors as close to
MSL3086/88 as possible and minimize trace lengths connected to COMP and FB.
LED Dimming Control
E
Control MSL3086/87 LED brightness using Pulse Width Modulation (PWM) with a PWM signal applied to the external
PWM input. The PWM dimming signals (outputs) take the frequency and duty cycle of the input signal but are staggere
in time so that they start at evenly spaced intervals relative to the PWM input signal. When one or more strings are
disabled by fault response, the stagger delays automatically re-calculate for the remaining enabled strings.

C
R
R
f
f
C
C
R
R
R
COMP
f
f
TOP
BOTTOM
where C
Assure that the loop crossover frequency is at least 1/5
Next determine the desired crossover frequency as 1/5
or the switching frequency f
where f
the resistor of the series RC compensation network. Rearranging the factors of this equation yields the solution for R
as:

These equations are accurate if the compensation zero (formed by the compensation resistor R
compensation capacitor C
compensation capacitor such that the compensation zero is 1/5
©
f
f
XTERNAL AND
f
f
TOP
BOTTOM
RHPZ
C
C
COMP
XTERNAL AND
R
TOP
BOTTOM
LOAD
RHPZ
COMP
C
COMP
XTERNAL AND
TOP
BOTTOM
LOAD
RHPZ
COMP
f
f
COMP
XTERNAL AND
C
COMPZ
LOAD
RHPZ
C
COMP
COMP
COMP
COMP
Atmel Inc., 2011. All rights reserved.
LOAD
COMP
COMP
COMP
C
COMPZ
COMP
COMP
Atmel Inc., 2011. All rights reserved.
R
R

) happens at a lower frequency than crossover. Therefore the next step is to choose the compensation capacitor such that the
= 49.9k
= 49.9k
TOP
BOTTOM

= 49.9k
C
= 49.9k
f





f

is the crossover frequency, R
f




f






RHPZ

C

RHPZ


= 3.40k
= 49.9k
RHPZ


R
= 3.40k
RHPZ
5
= 3.40k
5
C
= 3.40k



R
R
5



5
I



is the crossover frequency, R
V
R
OUT
R
V
I



R
2
COMP
COMP
V
I
V
R
2
V
is the crossover frequency, R
I
2
R
V
R
TOP
COMP
V
2
LOAD
V
LOAD
V
V
= 3.40k
TOP

R
OUT

TOP
OUT
LOAD
V
TOP

LOAD
V
OUT
TOP
OUT

f
OUT
TOP
TOP
OUT
5
OUT
COMP
OUT
IN
COMP
IN
TOP
f
COMP
C
5
IN



is the value of the output capacitor, and ESR is the Equivalent Series Resistance of the output capacitor.
COMP
IN
2


C
2
:


2

2

14



14


R

14

R












14
R





R






11

11
:
COMP
:

2
11
2
COMP

I
11
:
11
COMP
I
2
6 .
:
COMP
2
2
6 .
I
2
6 .
I
11
2




6 .
2
0
2
0

39
2
39
0

C C

C C





0
39
11
kHz

C C
39

8 .
kHz

1
C C
1
8 .
kHz

11

8 .



kHz
1



8 .
1
R




R
V



R
R
V
R
R
R
V
R
R
A
R

R
V
R

R
A
R

A

LOAD
R
2
A
CS


R
2
CS
2
LOAD
LOAD
CS
ONTROL OF
R
COMP
2
ONTROL OF
COMP
LOAD
CS
CS
COMP
LOAD

ONTROL OF

.
R
R
LOAD
ONTROL OF
COMP
.
f
5


CS

.
f
5

R

.
f
5
COMP
f
5

L
COMPZ
L

COMPZ
CS

COMP
L
COMPZ

L
COMPZ
COMP


CS
48
48
COMP

48
48
2
SW
2
1
2



2



2

SW


1











2
.

.
RHPZ


.

TOP
75

. The crossover frequency equation is:
.
75


75


) happens at a lower frequency than crossover. Therefore the next step is to choose th
. The crossover frequency equation is:
75



) happens at a lower frequency than crossover. Therefore the next step is to choose th








 

C

 







 

:
is the top side voltage divider resistor (from the output voltage to FB), R



 
2
C
f

12
39
12
th
f
MSL3086/MSL3087/MSL3088 Datashee
39
12
th
f
2
MSL3086/MSL3087/MSL3088 Datashee
39
f
12
th
f
MSL3086/MSL3087/MSL3088 Datashee
f
COMP
39
C

f
th
C
2
MSL3086/MSL3087/MSL3088 Datashe
f
2
C
f
f
2

COMP
C
C
2
C
f
f
C

COMP

C
C
f
RHPZ

C
f
RHPZ


 

LED


 
RHPZ

LED


 
RHPZ

LED


 
LED

2

2

C
C

2
TOP
.

R
2
C
.

C
C
.
TOP

.
R

, to set the compensation zero to 1/5th of the crossover frequency, or 3kHz
C

25
.
OUT

:
OUT
25
:
LOAD
25
:
OUT
.
25
OUT
OUT
:
1
LOAD



1



1
OUT



1
is the top side voltage divider resistor (from the output voltage to FB), R



1
BRIGHTNESS
2
k
BRIGHTNESS
is the top side voltage divider resistor (from the output voltage to FB), R
2
k
BRIGHTNESS
1
2
k
BRIGHTNESS
2
k





.





COMP

COMP


.
COMP
COMP


3

49
3

49
3

49
3
C
49
k
48
k
C
48

k

48
10
k
48

10

10
8-String 60mA LED Drivers with Integrated Boost Controller and Phase Shifted Dimming
OUT
10
9 .
, to set the compensation zero to 1/5
9 .
, to set the compensation zero to 1/5
OUT
9 .

, to set the compensation zero to 1/5
9 .

, to set the compensation zero to 1/5
.

.

.
75
.
75
k

75
k

75
k

k
2

2
2
2



10

10

1 .
10

1 .



10

1 .
Page 22 of 26
1 .
,
11
th
11
Page 22 of 26
11
nF
,
nF
11
th
nF
th


nF

of the lower of the ESR zero f

6
6
6
of the lower of the ESR zero f

of the ESR zero frequency.
6










.



.
.



.
.



.
.
025
.
025
025

025



73
73
th
73
73
th



of the crossover frequency, or:

kHz
of the crossover frequency, or:
kHz
kHz
2
kHz
2
2
2


Atmel MSL3086/MSL3088 Datasheet


ESRZ




15
15
15
, the right-half-plane zero f
15
k
k
k
k
COMP




20
20
20
20
and the compensation capacitor

COMP



F
F
F
F

as:



th
th
ESRZ
th
th
ESRZ
25
25
25
of the crossover frequency, or
25
of the crossover frequency, or
of the crossover frequency, o
of the crossover frequency, o
9 .
COMP
9 .
, the right-half-plane zero f
9 .
9 .
, the right-half-plane zero f
k
k
k
k
CS

RHPZ



is the resistor of
, and the
COMP
COMP
or the
and the
and the
21
COMP
COM
C
R
C
C
C
C