PM6600 STMicroelectronics, PM6600 Datasheet - Page 33

• 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
7.5
The SLOPE pin allows to properly set the amount of slope compensation connecting a
simple resistor R
starts at 35% (typ.) of each switching period and its slope is given by the following equation:
Equation 13
Where K
To avoid sub-harmonic instability, the compensating slope should be at least half the slope
of the inductor current during the off-phase for a duty-cycle greater than 50% (i.e. at the
lowest input voltage). The value of R
Equation 14
Figure 50. Effect of slope compensation on small inductor current perturbation
Soft-start
The soft-start function is required to perform a correct start-up of the system, controlling the
inrush current required to charge the output capacitor and to avoid output voltage overshoot.
The soft-start duration is set connecting an external capacitor between the SS pin and
ground. This capacitor is charged with a 5 μA constant current, forcing the voltage on the SS
pin to ramp up. When this voltage increases from zero to nearly 1.2 V, the current limit of the
power-MOSFET is proportionally released to its final value. In addition, during the initial part
of the Soft-Start, the switching frequency of the boost converter is reduced to half of the
Inductor current (CCM)
SLOPE
0.35
(D > 0.5)
·T
, V
ΔI
SW
SLOPE
BE
L
= 2 V (typ.) and SE is the slope ramp in [A/s].
T
Inductor current
perturbation
SW
between the SLOPE pin and the output. The compensation ramp
R
SLOPE
S
Doc ID 14248 Rev 7
E
≤
=
2
slope compensation (S
K
Programmed inductor peak current with
SLOPE
⋅
SLOPE
K
SLOPE
⎛
⎜ ⎜
⎝
can be calculated according to equation 9.
V
V (
⋅
OUT
L
OUT
⋅
R
V (
I
−
TRIP
SLOPE
OUT
−
V
IN
V
E
IN
)
−
−
)
V
V
BE
IN
−
⎞
⎟ ⎟
⎠
V
BE
)
Operation description
t
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