PM6600 STMicroelectronics, PM6600 Datasheet - Page 38

• 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

Backlight driver section
8.2
38/60
Equation 20
Due to the spread of the LEDs' forward voltage, the total drop across the LED's strings will
be different. The device will manage the unconnected ROWs according to the MODE pin
setting (see
PWM dimming
The brightness control of the LEDs is performed by a pulse-width modulation of the ROWs
current. When a PWM signal is applied to the DIM pin, the current generators are turned on
and off mirroring the DIM pin behavior. Actually, the minimum dimming duty-cycle depends
on the dimming frequency. The real limit to the PWM dimming is the minimum on-time that
can be managed for the current generators; this minimum on-time is approximately 500 ns.
Thus, the minimum dimming duty-cycle depends on the dimming frequency according to the
following formula:
Equation 21
For example, at a dimming frequency of 20 kHz, 1% of dimming duty-cycle can be
managed.
The device can manage the condition f
issue due to the human eye cutoff frequency, we recommend to use f
verified with discrete smd leds without any light guide).
The f
During the off-phase of the PWM signal the boost converter is paused, the current
generators are turned off and the output voltage is frozen across the output capacitor.
During the start-up sequence the dimming duty-cycle is forced to 100% to detect floating
ROWs regardless of the applied dimming signal.
DIM
maximum value has to be 1/10 of the selected F
Table 8
).
I
Δ
Δ
ROW
I
I
ROWx
ROWx
_
Doc ID 14248 Rev 7
mean
,
,
max
min
D
=
=
=
DIM
I
i
∑
I
ROW
=
6
ROW
1
DIM
,
I
min
ROWi
6
_
= 0 Hz. However, in order to avoid any flickering
_
I
min
ROW
=
I
max
ROW
500
−
_
−
I
_
mean
ROW
ns
I
mean
ROW
⋅
_
f
DIM
_
mean
mean
sw
≥
.
≤
−
+
2
2
%
%
DIM
> 100 Hz (condition
PM6600