PM6600 STMicroelectronics, PM6600 Datasheet - Page 51

• Manufacturer Part Number: PM6600
• Description: IC LED DRIVR WHT BCKLT 24-VFQFPN
• Manufacturer: STMicroelectronics
• Type: Backlight, White LEDr

Specifications of PM6600

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 6
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 200kHz ~ 1MHz
• Voltage - Supply: 4.7 V ~ 28 V
• Voltage - Output: 36V
• Mounting Type: Surface Mount
• Package / Case: 24-VFQFN, 24-VFQFPN
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 32mA
• Internal Switch(s): Yes
• Number Of Segments: 60
• Operating Supply Voltage: 4.7 V to 28 V
• Maximum Power Dissipation: 2.3 W
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• For Use With: 497-8414 - BOARD EVAL BASED ON PM6600
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Efficiency: -
• Lead Free Status / Rohs Status: Details

PM6600
B.4.4
It is important to highlight that the inductor choice involves not only the value itself but the
saturation current (higher than the boost current limit), the rated RMS current (the
compliance with the saturation current might be not enough; also the thermal performances
must be taken into account), the DCR (which affects the efficiency) and the size (in some
application might be a strict requirement).
However the DCR can’t be reduced keeping the size small. Hence a trade off between these
two requirements must be achieved according to the application.
Output capacitor choice
The choice of the output capacitor is mainly affected by the desired output voltage ripple.
Since the voltage across the LEDs can be considered almost constant, this ripple is
transferred across the current generators, affecting their dynamic response.
The output ripple can be estimated as (neglecting the contribution of ESR of C
in case of MLCC):
Equation 30
where I
Equation 31
whereas D, working in DCM, is:
Equation 32
defining M as:
Equation 33
T
Equation 34
OFF
can be calculated as:
L, peak
is the inductor peak current (see Figure 1) calculated as:
D
=
T
I
, L
OFF
peak
2
⋅
M
F
=
sw
=
T
=
SW
Doc ID 14248 Rev 7
F
⋅
V
V
L
R
Δ
sw
IN
V
OUT
⋅
V
0
⋅
IN
M
D
⋅
OUT
⋅
D
L
(
2
M
⎧
⎨
⎩
=
=
. 2
−
. 3
=
⎧
⎨
⎩
⎧
⎨
⎩
083
) 1
. 0
125
398
(
I
. 1
348
, L
914
=
peak
044
5 .
⎧
⎨
⎩
5 .
@
. 0
A
ns
2
@
. 0
A
ns
−
285
⋅
488
I
C
OUT
@
V
OUT
@
@
V
IN
@
IN
,
)
max
@
,
⋅
min
V
@
T
V
V
IN
V
OFF
IN
IN
,
=
IN
max
=
,
,
V
min
max
14
,
V
min
9
IN
IN
6 .
,
max
=
4 .
=
,
min
=
V
=
14
V
9
14
9
6 .
=
=
4 .
6 .
4 .
V
14
9
V
V
V
6 .
4 .
V
V
Application note
OUT
, very low
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