PM6600
6-row 32 mA LED driver with boost regulator
for LCD panel backlight
Features
■
■
Boost section
– 4.7 V to 28 V input voltage range
– Internal power MOSFET
– Internal +5 V LDO for device supply
– Up to 36 V output voltage
– Constant frequency peak current-mode
control
– 200 kHz to 1 MHz adjustable switching
frequency
– External synchronization for multi-device
application
– Pulse-skip power saving mode at light load
– Programmable soft-start
– Programmable OVP protection
– Stable with ceramic output capacitors
– Thermal shutdown
Backlight driver section
– Six rows with 32 mA maximum current
capability (adjustable)
– Up to 10 WLEDs per row
– Unused rows detection
– 500 ns minimum dimming time (1 %
minimum dimming duty-cycle at 20 kHz)
– ±2.1 % current accuracy
– ±2 % current matching between rows
– LED failure (open and short circuit)
detection
VFQFPN-24 4x4
Description
The PM6600 consists of a high efficiency
monolithic boost converter and six controlled
current generators (ROWs), specifically designed
to supply LEDs arrays used in the backlight of
LCD panels. The device can manage a nominal
output voltage up to 36 V (i.e. 10 White-LEDs per
ROW). The generators can be externally
programmed to sink up to 32 mA and they can be
dimmed via a PWM signal (1% dimming dutycycle at 20 kHz can be managed). The device
allows to detect and manage the open and
shorted LED faults and to let unused ROWs
floating. Basic protections (Output Over-Voltage,
internal MOSFET Over-Current and Thermal
Shutdown) are provided.
Applications
■
Notebook monitors backlight
■
UMPC backlight
Table 1.
Device summary
Order codes
Package
PM6600
Packaging
Tube
VFQFPN-24 4x4 (exposed pad)
PM6600TR
April 2008
Tape and reel
Rev 3
1/43
www.st.com
Contents
PM6600
Contents
1
Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2
Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3
2.1
Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1
Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3
Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5
Typical operating characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7
Operation description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.1
Boost section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.1.1
2/43
Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.2
Over voltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.3
Switching frequency selection and synchronization . . . . . . . . . . . . . . . . . 25
7.4
System stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.4.1
Loop compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.4.2
Slope compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7.5
Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7.6
Boost current limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.7
Enable function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.8
Thermal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
PM6600
8
9
Contents
Backlight driver section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.1
Current generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.2
PWM dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Fault management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
9.1
FAULT pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
9.2
MODE pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
9.3
Open LED fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9.4
Shorted LED fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9.5
Intermittent connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
10
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
11
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3/43
VIN-
DIM
EN
FAULT
AVCC
MODE
SW3
Ccomp
Rcomp
Css
Rf sw
6
SS
COMP
MODE
DIM
EN
FAULT
LDO5
AVCC
FSW
SW2
24
1
5
20
21
22
7
Rf ilt
AVCC
Cldo5
AVCC
23
SYNC
8
VIN
PM6600
Rrilim
FSW
Cav cc
RILIM
Cin
L
19
THPD
ROW6
ROW5
ROW4
ROW3
ROW2
ROW1
PGND
SLOPE
OVSEL
Rbilim
BILIM
LX
4/43
4
25
16
15
14
13
12
11
17
9
18
D
C13
C10
R1
R2
Rslope
Cout
VBOOST
Application circuit
2
Figure 1.
3
Typical application circuit
SGND
1
10
VIN+
Typical application circuit
PM6600
PM6600
Pin settings
2
Pin settings
2.1
Connections
Figure 2.
2.2
Pin connection (through top view)
Pin description
Table 2.
Pin functions
N°
Pin
Function
1
COMP
Error amplifier output. A simple RC series between this pin and ground is
needed to compensate the loop of the boost regulator.
2
RILIM
Output generators current limit setting. The output current of the ROWs can
be programmed connecting a resistor to SGND.
3
BILIM
Boost converter current limit setting. The internal MOSFET current limit can
be programmed connecting a resistor to SGND.
4
FSW
Switching frequency selection and external sync input. A resistor to SGND
is used to set the desired switching frequency. The pin can also be used as
external synchronization input. See Section 7.3 on page 25 for details.
5
MODE
Current generators fault management selector. It allows to detect and
manage LEDs failures. See Section 9.2 on page 36 for details.
6
AVCC
+5 V analog supply. Connect to LDO5 through a simple RC filter.
7
LDO5
Internal +5 V LDO output and power section supply. Bypass to SGND with a
1 µF ceramic capacitor.
8
VIN
Input voltage. Connect to the main supply rail.
5/43
Pin settings
PM6600
Table 2.
6/43
Pin functions (continued)
N°
Pin
Function
9
SLOPE
Slope compensation setting. A resistor between the output of the boost
converter and this pin is needed to avoid sub-harmonic instability.
Refer to section 1.4 for details.
10
SGND
Signal ground. Supply return for the analog circuitry and the current
generators.
11
ROW1
Row driver output #1.
12
ROW2
Row driver output #2.
13
ROW3
Row driver output #3.
14
ROW4
Row driver output #4.
15
ROW5
Row driver output #5.
16
ROW6
Row driver output #6.
17
PGND
Power ground. Source of the internal power-MOSFET.
18
OVSEL
Over-voltage selection. Used to set the desired OV threshold by an external
divider. See Section 7.2 on page 24 for details.
19
LX
20
DIM
Dimming input. Used to externally set the brightness of the LEDs by using a
PWM signal.
21
EN
Enable input. When low, the device is turned off. If tied high or left floating,
the device is turned on and a Soft-Start sequence takes place.
22
FAULT
Fault signal output. Open drain output. The pin goes low when a fault
condition is detected (see Section 9.1 on page 36 for details).
23
SYNC
Synchronization output. Used as external synchronization output.
24
SS
Switching node. Drain of the internal power-MOSFET.
Soft start. Connect a capacitor to SGND to set the desired Soft-Start
duration.
PM6600
Electrical data
3
Electrical data
3.1
Maximum rating
Table 3.
Absolute maximum ratings (1)
Symbol
Parameter
Value
VAVCC
AVCC to SGND
-0.3 to 6
VLDO5
LDO5 to SGND
-0.3 to 6
PGND to SGND
-0.3 to 0.3
VIN
VIN to PGND
-0.3 to 40
VLX
LX to SGND
-0.3 to 40
LX to PGND
-0.3 to 40
RILIM, BILIM, SYNC, OVSEL, SS to SGND
EN, DIM, FSW, MODE, FAULT to SGND
-0.3 to 6
ROWx to PGND/ SGND
-0.3 to 40
V
VIN - 0.3 to
VIN + 6
SLOPE to VIN
SLOPE to SGND
PTOT
-0.3 to
VAVCC + 0.3
Unit
-0.3 to 40
Maximum LX RMS current
2.0
A
Power dissipation @=25°C
2.3
W
±1000
V
Maximum withstanding voltage range test condition:
CDF-AEC-Q100-002- “Human Body Model”
acceptance criteria: “Normal Performance”
1. Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the
device. Exposure to absolute maximum rated conditions for extended periods may affect device reliability.
3.2
Thermal data
Table 4.
Symbol
Thermal data
Parameter
Value
Unit
42
°C/W
RthJA
Thermal resistance junction to ambient
TSTG
Storage temperature range
-50 to 150
°C
TJ
Junction operating temperature range
-40 to 125
°C
TA
Operating ambient temperature range
-40 to 85
°C
7/43
Electrical data
3.3
PM6600
Recommended operating conditions
Table 5.
Recommended operating conditions
Values
Symbol
Parameter
Unit
Min
Typ
Max
Supply section
VIN
Input voltage range
4.7
28
V
36
V
1000
kHz
FSW sync input
Duty-Cycle
40
%
ROWs output maximum
current
32
mA
Boost section
VBST
Output voltage range
fSW
Adjustable switching
frequency
Irowx
8/43
FSW connected
to RFSW
200
PM6600
4
Electrical characteristics
Electrical characteristics
VIN = 12 V; TA = 0 °C to 85 °C and MODE connected to AVCC unless specified (1).
Table 6.
Electrical characteristics
Values
Symbol
Parameter
Test condition
Unit
Min
Typ
Max
4.6
5
5.5
Supply section
VLDO5, VAVCC LDO output and IC supply voltage
IIN,Q
IIN,SHDN
EN High,
ILDO5 = 0 mA
Operating quiescent current
RRILIM = 51 kΩ,
RBILIM = 220 kΩ,
RSLOPE = 680 kΩ
DIM tied to SGND.
1
Operating current in shutdown
EN low
20
30
4.6
4.75
VUVLO,ON
LDO5 under voltage lockout upper
threshold
VUVLO,OFF
LDO5 under voltage lockout lower
threshold
V
mA
µA
V
3.8
4.0
LDO linear regulator
Line regulation
6 V = VIN = 28 V,
ILDO5 = 30 mA
LDO dropout voltage
VIN = 4.3 V,
ILDO5 = 10 mA
LDO maximum output current limit
VLDO5 > VUVLO,ON
25
mV
25
80
120
40
60
VLDO5 < VUVLO,OFF
mA
30
1. TA = TJ. All parameters at operating temperature extremes are guaranteed by design and statistical analysis
(not production tested)
9/43
Electrical characteristics
Table 6.
PM6600
Electrical characteristics (continued)
Values
Symbol
Parameter
Test condition
Unit
Min
Typ
Max
Boost section
ton,min
Minimum switching
on time
Default switching frequency
200
FSW connected to AVCC
570
660
ns
750
kHz
Minimum FSW
Sync frequency
210
FSW Sync
Input low level threshold
240
mV
FSW Sync
Input hysteresis
60
FSW Sync
Min ON time
SYNC output
Duty-Cycle
FSW connected to AVCC
(Internal Oscillator
Selected)
SYNC output
High Level
ISYNC = 10 uA
34
270
ns
40
%
VAVCC
-20
mV
SYNC output
Low Level
ISYNC = -10 uA
LX current coefficient
RBILIM = 300 kΩ
20
Power switch
KB
5.7e5
Internal MOSFET RDSon
6.7e5
7.7e5
V
280
500
mΩ
V
OV protections
VTH,OVP
Over-voltage protection reference
(OVSEL) threshold
1.190
1.235
1.280
VTH,FRD
Floating ROWs detection
(OVSEL) threshold
1.100
1.145
1.190
∆VOVP,FRD
10/43
Voltage gap between the OVP
and FRD thresholds
90
mV
PM6600
Table 6.
Electrical characteristics
Electrical characteristics (continued)
Values
Symbol
Parameter
Test condition
Unit
Min
Typ
Max
Soft start and power management
EN, Turn-On level threshold
1.6
EN, Turn-Off level threshold
V
0.8
DIM, high level threshold
1.3
DIM, low level threshold
0.8
EN, Pull-up current
µA
2.5
SS, charge current
4
5
6
SS, End-Of-Startup threshold
2
2.4
2.8
SS, Reduced switching frequency
Release threshold
V
0.8
Current generators section
Minimum dimming On-Time
RRILIM = 51 kΩ
500
ROWs current coefficient
accuracy
RRILIM = 51 kΩ
998
ROWs current mismatch(1)
RRILIM = 51 kΩ
VIFB
Feedback regulation voltage
No LEDs mismatch
VTH,FAULT
Shorted LED fault detection
threshold
VFAULT,LOW
FAULT pin low-level voltage
TDIM-ON,min
KR
∆IROWx
ns
±21
V
±2
%
400
mV
8.2
V
IFAULT,SINK = 4 mA
350
mV
Thermal shutdown
TSHDN
Note:
Thermal shutdown
Turn-off temperature
150
°C
The Current Mismatch is the maximum current difference among the ROWs of one device.
11/43
Typical operating characteristics
5
PM6600
Typical operating characteristics
All the measures are done with a standard PM6600EVAL demoboard and a standard
WLED6021NB demoboard, with the components listed in the EVAL_KIT document.
The measures are done with this working conditions, unless specified:
Figure 3.
●
Vin = 12 V
●
Vout = 6 rows x 10 WLEDs = 34 V (typ)
●
Iout = 20 mA each row
●
fsw = 660 kHz (nominal switching frequency, with FSW .. AVCC)
●
Vrow1 to Vrow6 = {0.697, 0.75, 0.818, 0.696, 0.822, 0.363} V
Efficiency vs
DIM duty cycle @ fDIM = 200 Hz
Figure 4.
100
100
90
90
80
80
Efficiency [%]
70
Efficiency vs
DIM duty cycle @ fDIM = 500 Hz
70
Efficiency [%]
60
50
40
Vin = 6V
30
10
50
40
Vin = 6V
30
Vin = 12V
20
60
Vin = 12V
Vin = 18V
20
Vin = 24V
10
0
Vin = 18V
Vin = 24V
0
0
20
40
60
80
100
0
20
DIM duty cycle [%]
Figure 5.
Efficiency vs
DIM duty cycle @ fDIM = 1 kHz
Figure 6.
100
90
90
80
80
70
70
60
Efficiency [%]
Efficiency [%]
100
50
40
Vin = 6V
30
10
80
100
Efficiency vs
DIM duty cycle @ fDIM = 5 kHz
60
50
40
Vin = 6V
Vin = 12V
Vin = 18V
20
Vin = 18V
Vin = 24V
10
Vin = 24V
0
0
0
20
40
60
DIM duty cycle [%]
12/43
60
30
Vin = 12V
20
40
DIM duty cycle [%]
80
100
0
20
40
60
DIM duty cycle [%]
80
100
PM6600
Figure 8.
Efficiency vs
DIM duty cycle @ fDIM = 10 kHz
100
100
90
90
80
80
70
70
Efficiency [%]
Efficiency [%]
Figure 7.
Typical operating characteristics
60
50
40
Vin = 6V
30
Efficiency vs
DIM duty cycle @ fDIM = 20 kHz
60
50
40
Vin = 6V
30
Vin = 12V
20
Vin = 12V
20
Vin = 18V
10
Vin = 18V
10
Vin = 24V
0
Vin = 24V
0
0
20
40
60
80
100
0
20
DIM duty cycle [%]
Efficiency vs
DIM duty cycle @ Vin = 8 V
100
100
90
90
80
80
70
70
60
50
fDIM = 200Hz
40
fDIM = 500Hz
30
fDIM = 1kHz
20
fDIM = 5kHz
50
fDIM = 500Hz
30
fDIM = 1kHz
20
fDIM = 5kHz
0
20
40
60
80
fDIM = 10kHz
fDIM = 20kHz
0
100
0
20
40
DIM duty cycle [%]
60
100
Figure 12. Efficiency vs
DIM duty cycle @ Vin = 24 V
100
90
90
80
80
70
70
Efficiency [%]
100
60
fDIM = 200Hz
40
fDIM = 500Hz
30
fDIM = 1kHz
20
fDIM = 5kHz
60
50
fDIM = 200Hz
40
fDIM = 500Hz
30
fDIM = 1kHz
20
fDIM = 5kHz
fDIM = 10kHz
10
80
DIM duty cycle [%]
Figure 11. Efficiency vs
DIM duty cycle @ Vin = 18 V
50
100
fDIM = 200Hz
40
10
fDIM = 20kHz
0
80
60
fDIM = 10kHz
10
Efficiency [%]
60
Figure 10. Efficiency vs
DIM duty cycle @ Vin = 12 V
Efficiency [%]
Efficiency [%]
Figure 9.
40
DIM duty cycle [%]
fDIM = 10kHz
10
fDIM = 20kHz
0
fDIM = 20kHz
0
0
20
40
60
DIM duty cycle [%]
80
100
0
20
40
60
80
100
DIM duty cycle [%]
13/43
Typical operating characteristics
PM6600
Figure 14. Efficiency
vs Vin @ DIM duty cycles = 50 %
100
100
90
90
80
80
70
70
Efficiency [%]
Efficiency [%]
Figure 13. Efficiency
vs Vin @ DIM duty cycles = 10 %
60
50
fDIM = 200Hz
40
fDIM = 500Hz
fDIM = 1kHz
30
60
fDIM = 200Hz
50
fDIM = 500Hz
40
fDIM = 1kHz
30
fDIM = 5kHz
fDIM = 5kHz
20
fDIM = 10kHz
20
fDIM = 10kHz
10
fDIM = 20kHz
10
fDIM = 20kHz
0
0
6
12
18
6
24
12
Figure 15. Efficiency
vs Vin @ DIM duty cycles = 75 %
96
95
94
94
93
Efficiency [%]
90
fDIM = 200Hz
fDIM = 500Hz
88
fDIM = 1kHz
86
fDIM = 5kHz
92
fDIM = 200Hz
91
fDIM = 500Hz
90
fDIM = 1kHz
fDIM = 5kHz
89
fDIM = 10kHz
84
fDIM = 10kHz
88
fDIM = 20kHz
82
fDIM = 20kHz
87
6
12
18
Vin [V]
14/43
24
Figure 16. Efficiency
vs Vin @ DIM duty cycles = 100 %
92
Efficiency [%]
18
Vin [V]
Vin [V]
24
6
12
18
Vin [V]
24
PM6600
Typical operating characteristics
Figure 17. Working waveforms @
fDIM = 100 Hz, D = 1 %
Figure 18. Working waveforms @
fDIM = 100 Hz, D = 10 %
Figure 19. Working waveforms @
fDIM = 100 Hz, D = 50 %
Figure 20. Working waveforms @
fDIM = 100 Hz, D = 80 %
15/43
Typical operating characteristics
PM6600
Figure 21. Working waveforms @
fDIM = 200 Hz, D = 1 %
Figure 22. Working waveforms @
fDIM = 200 Hz, D = 20 %
Figure 23. Working waveforms @
fDIM = 200 Hz, D = 50 %
Figure 24. Working waveforms @
fDIM = 200 Hz, D = 80 %
16/43
PM6600
Typical operating characteristics
Figure 25. Working waveforms @
fDIM = 500 Hz, D = 1 %
Figure 26. Working waveforms @
fDIM = 500 Hz, D = 50 %
Figure 27. Working waveforms @
fDIM = 1 kHz, D = 1%
Figure 28. Working waveforms @
fDIM = 1 kHz, D = 50 %
17/43
Typical operating characteristics
PM6600
Figure 29. Working waveforms @
fDIM = 10 kHz, D = 1 %
Figure 30. Working waveforms @
fDIM = 10 kHz, D = 50 %
Figure 31. Working waveforms @
fDIM = 20 kHz, D = 1 %
Figure 32. Working waveforms @
fDIM = 20 Hz, D = 50 %
18/43
PM6600
Typical operating characteristics
Figure 33. Output voltage ripple @
fDIM = 200 Hz, D = 1 %
Figure 34. Output voltage ripple @
fDIM = 200 Hz, D = 20 %
Figure 35. Output voltage ripple @
fDIM = 200 Hz, D = 50 %
Figure 36. Output voltage ripple @
fDIM = 200 Hz, D = 80 %
19/43
Typical operating characteristics
PM6600
Figure 37. Shorted LED protection
@ fDIM = 200 Hz
All WLEDs connected
Figure 38. Shorted LED protection
@ fDIM = 200 Hz
1 WLED shorted
Figure 39. Shorted LED protection
@ fDIM = 200 Hz
2 WLEDs shorted
Figure 40. Shorted LED protection
@ fDIM = 200 Hz
3 WLEDs shorted - ROW disabled
20/43
PM6600
Typical operating characteristics
Figure 41. Open ROW detection @
fDIM = 200 Hz
21/43
Block diagram
6
PM6600
Block diagram
Figure 42. Simplified block diagram
VIN
SLOPE
Current Sense
LDO5
+5V
LDO
Ramp
Generator
+ +
+
UVLO
Detector
Boost
Control
Logic
_
UVLO
+
gm
_
COMP
LX
ZCD
0.4V
PGND
Boost_EN
BILIM
SS
Current Limit
_
FRD
+
_
OVP
Min Voltage
Selector
Soft Start
CTRL6
÷2
1.235V
Current
Generator 6
ROW6
Current
Generator 5
ROW5
Current
Generator 4
ROW4
Current
Generator 3
ROW3
Current
Generator 2
ROW2
VROW5
CTRL5
Ext Sync
Detector
OVSEL
VROW6
Prot_EN
SYNC
1.143V
+
VROW4
OSC
CTRL4
VROW3
FSW
CTRL3
VROW2
Prot_EN
CTRL2
Boost_EN
AVCC
EN
MODE
UVLO
CONTROL
LOGIC
CTRL6
CTRL5
CTRL4
CTRL3
CTRL2
8.2V
VTH,FLT
CTRL1
LOGIC
VROW1
ROW1
OVP
FAULT
FRD
I to V
+
_
DIM
I to V
Thermal
Shutdown
Current
Generator 1
1.2V
RILIM
22/43
SGND
PM6600
Operation description
7
Operation description
7.1
Boost section
7.1.1
Functional description
The PM6600 is a monolithic LEDs driver for the backlight of LCD panels and it consists of a
boost converter and six PWM-dimmable current generators.
The input voltage range is from 4.7 V up to 28 V.
The boost section is based on a constant switching frequency, Peak Current-Mode
architecture. The boost output voltage is controlled such that the lowest ROWs' voltage,
referred to SGND, is equal to an internal reference voltage (400 mV typ.).
In addition, the PM6600 has an internal LDO that supplies the internal circuitry of the device
and is capable to deliver up to 40 mA. The input of the LDO is the VIN pin. The LDO5 pin is
the LDO output and the supply for the power-MOSFET driver at the same time. The AVCC
pin is the supply for the analog circuitry and should be connected to the LDO output through
a simple RC filter, in order to improve the noise rejection.
Figure 43. AVCC filtering
VIN
LDO5
Rfilt
4R7
LDO
PM6600
AVCC
Cavcc
100n
SGND
Two loops are involved in regulating the current sunk by the generators.
The main loop is related to the boost regulator and uses a constant frequency Peak CurrentMode architecture (see Figure 49), while an internal current loop regulates the same current
at each ROW according to the set value (RILIM pin).
A dedicated circuit automatically selects the lowest voltage drop among all the ROWs and
provides this voltage the main loop that, in turn, regulates the output voltage. In fact, once
the reference generator has been detected, the error amplifier compares its voltage drop to
the internal reference voltage and varies the COMP output. The voltage at the COMP pin
determines the inductor peak current at each switching cycle. The output voltage of the
boost regulator is thus determined by the total forward voltage of the LEDs strings:
Equation 1
NROWS mLEDS
VOUT = max (
i=1
Σ
VF,j ) + 400mV
j=1
23/43
Operation description
PM6600
where the first term represents the highest total forward voltage drop over active ROWs and
the second is the voltage drop across the leading generator (400 mV typ.).
The device continues to monitor the voltage drop across all the rows and automatically
switches to the current generator having the lowest voltage drop.
7.2
Over voltage protection
An adjustable Over-Voltage Protection is available. It can be set feeding the OVSEL pin with
a partition of the output voltage. The voltage of the central tap of the divider is thus
compared to a fixed 1.235 V threshold. When the voltage on the OVSEL pin exceeds the OV
threshold, the FAULT pin is tied low (see Section 9 on page 36) and the device is turned off;
this condition is latched and the PM6600 is restarted by toggling the EN pin or by performing
a Power-On Reset (the POR occurs when the LDO output falls below the lower UVLO
threshold and subsequently crosses the upper UVLO threshold during the rising phase of
the input voltage). Normally, the value of the high-side resistors of the divider is in the order
of 100kΩ to reduce the output capacitor discharge when the boost converter is off (during
the off phase of the dimming cycle).
The OVSEL divider should be a compensated one, with the capacitors C10 (typically in the
100 pF-330 pF range) that improves noise rejection at the OVSEL pin (see Figure 44) and
C13 (typically 22 pF) that avoids OVP fault detection when a row is open.
The following formula permits to properly select the OVP threshold, according to the VOUT
value and considering the worst case:
Equation 2
VOUT < VOVP < VOUT + (VROWx,FAULT − VROW _ MAX )
where
Equation 3
VOUT = n WLED _ series ⋅ VF _ WLED + 0.4V
VOVP is the Over-Voltage Protection threshold
VROWx,FAULT is the Shorted LED threshold
VROW_MAX is the maximum voltage drop across the current generators, measured in the
ROWx pin with the leds' series with minimum VF_WLED: Forward Voltage of the single LED.
24/43
PM6600
Operation description
Figure 44. OVP threshold setting
VIN
VOUT
C13
LX
PM6600
R1
COUT
OVSEL
R2
C10
SGND
7.3
Switching frequency selection and synchronization
The switching frequency of the boost converter can be set in the 200 kHz-1 MHz range by
connecting the FSW pin to ground through a resistor. Calculation of the setting resistor is
made using equation 3 and should not exceed the 80 kΩ-400 kΩ range.
Equation 4
RFSW =
fSW
2 .5
In addition, when the FSW pin is tied to AVCC, the PM6600 uses a default 660 kHz fixed
switching frequency, allowing to save a resistor in minimum components-count applications.
Figure 45. Multiple device synchronization
SLAVE
MASTER
AVCC
Sync Out
FSW
SYNC
PM6600
RFSW
SGND
FSW
SYNC
SYNC
PM6600
SGND
The FSW pin can also be used as a synchronization input, allowing the PM6600 to operate
both as master or slave device. If a clock signal with a 210 kHz minimum frequency is
applied to this pin, the device locks synchronized (300 mV threshold). An Internal timeout
allows synchronization as long as the external clock frequency is greater than 210 kHz.
Keeping the FSW pin voltage lower than 300 mV for more than 1/210 kHz ≈ 5 µs results in
the device turn off. Normal operation is resumed as soon as FSW rises above the
mentioned threshold and the Soft-Start sequence is repeated.
25/43
Operation description
PM6600
The SYNC pin is a synchronization output and provides a 34 % (typ.) duty-cycle clock when
the PM6600 is used as master or a replica of the FSW pin when used as slave. It is used to
connect multiple devices in a daisy-chain configuration or to synchronize other switching
converters running in the system with the PM6600 (master operation).
When an external synchronization clock is applied to the FSW pin, the internal oscillator is
overdriven: each switching cycle begins at the rising edge of clock, while the slope
compensation ramp starts at the falling edge of the same signal. Thus, the external
synchronization clock is required to have a 40 % maximum duty-cycle when the boost
converter is working in Continuous-Conduction Mode (CCM). The minimum pulse width
which allows the synchronizing pulses to be detected is 270 ns.
Figure 46. External sync waveforms
270ns minimum
FSW pin voltage (ext. sync)
300mV threshold
Slave SYNC pin voltage
Slave LX pin voltage
26/43
PM6600
7.4
Operation description
System stability
The boost section of the PM6600 is a Fixed Frequency, Peak Current-Mode converter.
During normal operation, a minimum voltage selection circuit compares all the voltage drops
across the active current generators and provides the minimum one to the error amplifier.
The output voltage of the error amplifier determines the inductor peak current in order to
keep its inverting input equal to the reference voltage (400 mV typ). The compensation
network consists of a simple RC series (RCOMP - CCOMP) between the COMP pin and
ground.
The calculation of RCOMP and CCOMP is fundamental to achieve optimal loop stability and
dynamic performance of the boost converter and is strictly related to the operating
conditions.
7.4.1
Loop compensation
The compensation network can be quickly calculated using equations 4 through 9. Once
both RCOMP and CCOMP have been determined, a fine-tuning phase may be required in
order to get the optimal dynamic performance from the application.
The first parameter to be fixed is the switching frequency. Normally, a high switching
frequency allows reducing the size of the inductor but increases the switching losses and
negatively affects the dynamic response of the converter. For most of applications, the fixed
value (660 kHz) represents a good trade-off between power dissipation and dynamic
response, allowing to save an external resistor at the same time. In low-profile applications,
the inductor value is often kept low to reduce the number of turns; an inductor value in the
4.7 µH-15 µH range is a good starting choice.
Even if the loop bandwidth of the boost converter should be chosen as large as possible, it
should be set to 20 % of the switching frequency, taking care not to exceed the CCM-mode
Right Half-Plane Zero (RHPZ).
Equation 5
fU ≤ 0.2 ⋅ fSW
Equation 6
2
⎛ VIN,min ⎞ ⎛ VOUT
⎟ ⎜
⎜⎜
2
VOUT ⎟⎠ ⎜⎝ IOUT
M R
⎝
fU ≤ 0.2 ⋅
= 0 .2 ⋅
2π ⋅ L
2π ⋅ L
⎞
⎟⎟
⎠
Where VIN,min is the minimum input voltage, IOUT is the overall output current,
M=
VIN,min
VOUT
R=
VOUT
IOUT
Note that, the lower the inductor value (or the lower the switching frequency) the higher the
bandwidth can be achieved. The output capacitor is directly involved in the loop of the boost
converter and must be large enough to avoid excessive output voltage drop in case of a
sudden line transition from the maximum to the minimum input voltages (∆VOUT should not
exceed 50-100 mV):
27/43
Operation description
PM6600
Equation 7
∆VOUT =
V
IOUT ⎛⎜
1 − IN _ MIN
⎜
2π ⋅ fU ⋅ C ⎝
VIN _ MAX
⎞
⎟
⎟
⎠
Once the output capacitor has been chosen, the RCOMP can be calculated as:
Equation 8
R COMP =
2π ⋅ fU ⋅ C
GM ⋅ gEA ⋅ M
Where GM = 2.7 S and gEA = 375 µS.
The CCOMP capacitor is determined to place the frequency of the compensation zero 5
times lower than the loop bandwidth:
Equation 9
C COMP =
1
2π ⋅ fZ ⋅ R COMP
Where fZ = fU / 5.
The close loop gain function (GLOOP) is thus given by equation 10:
Equation 10
GLOOP = GM ⋅ gEA
⎛
1
⋅ ⎜⎜ R COMP +
sC COMP
⎝
L
1− s 2
⎞
M R
⎟⎟ ⋅ RM
1 + sRC
⎠
A simple technique to optimize different applications is to replace RCOMP with a 20kΩ
trimmer and adjust its value to properly damp the output transient response. Insufficient
damping will result in excessive ringing at the output and poor phase margin. Figures 5a and
5b give an example of compensation adjustment for a typical application.
Figure 47. Poor phase margin (a) and properly damped (b) load transient responses
28/43
PM6600
Operation description
Figure 48. Load transient response measurement set-up
6.8μH
VIN= 6V
VBST=30÷36V
CIN
4.7μF
MLCC
FSW
OVSEL
LX
LDO5
SLOPE
VIN
AVCC
+5V
ROW1
PM6600
RILIM
PGND
ROW6
MODE
SGND
SYNC
ROW5
EN
ROW4
COMP
FAULT
VBST
50mA
ROW3
SS
DIM
7.4.2
RL =
ROW2
BILIM
500Hz
Up to 10 WLEDs per row
Slope compensation
The Constant Frequency, Peak Current-Mode topology has the advantage of very easy loop
compensation with output ceramic capacitors (reduced cost and size of the application) and
fast transient response. In addition, the intrinsic peak-current measurement simplifies the
current limit protection, avoiding undesired saturation of the inductor.
On the other side, this topology has a drawback: there is inherent open loop instability when
operating with a duty-ratio greater than 0.5. This phenomenon is known as "Sub-Harmonic
Instability" and can be avoided by adding an external ramp to the one coming from the
sensed current. This compensating technique, based on the additional ramp, is called
"Slope Compensation". In figure 11, where the switching duty-cycle is higher than 0.5, the
small perturbation ∆IL dies away in subsequent cycles thanks to the slope compensation
and the system reverts to a stable situation.
Figure 49. Main loop and current loop diagram
VIN
ROWx
LX
SGND
PWM
COMP
gm
Minimum voltage drop
selector
RILIM
0.4V
29/43
Operation description
PM6600
The SLOPE pin allows to properly set the amount of slope compensation connecting a
simple resistor RSLOPE between the SLOPE pin and the output. The compensation ramp
starts at 35 % (typ.) of each switching period and its slope is given by the following equation:
Equation 11
⎛V
− VIN − VBE
SE = K SLOPE ⎜⎜ OUT
R
SLOPE
⎝
⎞
⎟⎟
⎠
Where KSLOPE, VBE = 2 V (typ.) and SE is the slope ramp in [A/s].
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 RSLOPE can be calculated according to equation 9.
Equation 12
R SLOPE ≤
2 ⋅ K SLOPE ⋅ L ⋅ (VOUT − VIN − VBE )
(VOUT − VIN )
Figure 50. Effect of slope compensation on small inductor current perturbation
(D > 0.5)
Inductor current (CCM)
Programmed inductor peak current with
slope compensation (SE)
0.35·TSW
ITRIP
∆IL
Inductor current
perturbation
TSW
30/43
t
PM6600
7.5
Operation description
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
nominal value to permit to use inductors with lower saturation current value; the nominal
switching frequency is restored after the SS pin voltage has crossed 0.8 V. In this mode, the
current runaway is avoided.
Figure 51. Soft-start sequence waveforms in case of floating ROWs
OVP
Floating ROWs detection
93% of OVP
Output voltage
SS pin voltage
AVCC
Protections turn active
2.4V
1.2V
0.8V
Nominal switching
frequency release
tss
Current limit
100%
EN pin voltage
t
During the soft-start phase it is also performed the floating ROWs detection. In presence of
one or more floating ROWs, the error amplifier is unbalanced and the output voltage
increases; when it reaches the Floating ROW Detection (FRD) threshold (93 % of the OVP
threshold), the floating ROWs are managed according to Table 3 (see Section 9 on page 36).
After the SS voltage reaches a 2.4 V threshold, the start-up finishes and all the protections
turn active. The soft-start capacitor CSS can be calculated according to equations 12.
Equation 13
C SS ≅
ISS t SS
2 .5
C SS ≅ 12 ⋅ 10 −6 ⋅ C OUT ⋅ (VOUT,max − VIN,min )
Where ISS = 5 µA and tSS is the desired Soft-start duration.
31/43
Operation description
7.6
PM6600
Boost current limit
The design of the external components, especially the inductor and the flywheel diode, must
be optimized in terms of size relying on the programmable peak current limit. The PM6600
improves the reliability of the final application giving the way to limit the maximum current
flowing into the critical components. A simple resistor connected between the BILIM pin and
ground sets the desired value. The voltage at the BILIM pin is internally fixed to 1.2 V and
the current limit is proportional to the current flowing through the setting resistor, according
to the following equation:
Equation 14
IBOOST,PEAK =
KB
RBILIM
where K B = 6.7 ⋅ 10 5 V ± 15% .
The maximum allowed current limit is 5 A, resulting in a minimum setting resistor
RBILIM > 120 kΩ. The maximum guaranteed RMS current in the power switch is 2 Arms. The
current limitation works by clamping the COMP pin voltage proportionally to RBILIM. Peak
inductor current is limited to the above threshold decreased by the slope compensation
contribution.
In a boost converter the r.m.s. current through the internal MOSFET depends on both the
input and output voltages, according to equations 15a (DCM) and 15b (CCM).
Equation 15 a
IMOS,rms =
VIN ⋅ D D
FSW ⋅ L 3
Equation 15 b
IMOS,rms = IOUT
32/43
2
⎛ D
⎞
⎞
VOUT
1⎛
3⎟
⎜
⎜
⎟
(
(
)
)
+
−
D
1
D
⎟
⎜ (1 − D)2 12 ⎜ I
⎟
⎝ OUT ⋅ fSW ⋅ L ⎠
⎝
⎠
PM6600
7.7
Operation description
Enable function
The PM6600 is enabled by the EN pin. This pin is active high and, when forced to SGND,
the device is turned off. This pin is connected to a permanently active 2 µA current source;
when sudden device turn-on at power-up is required, this pin must be left floating or
connected to a delay capacitor. When turned off, the PM6600 quickly discharges the SoftStart capacitor and turns off the power-MOSFET, the current generators and the LDO. The
power consumption is thus reduced to 20 µA only.
The proper startup sequence is DIM ' VIN ' EN, or VIN ' DIM ' EN. If the dimming signal is
applied after the EN pin, the device will not perform the soft start again, in fact it will start
switching with the maximum current limit in order to recover the output voltage.
In applications where the dimming signal is used to turn on and off the device, the EN pin
can be connected to the DIM pin as shown in Figure 52.
Figure 52. fDIM enabling schematic
DIM
PM6600
BAS69
EN
220k
100n
SGND
7.8
Thermal protection
In order to avoid damage due to high junction temperature, a thermal shutdown protection is
implemented. When the junction temperature rises above 150 °C (typ.), the device turns off
both the control logic and the boost converter and holds the FAULT pin low.
In order to turn on the device again, it is possible to perform a POR (Power On Reset) once
the junction temperature has been reduced by 30 °C.
33/43
Backlight driver section
PM6600
8
Backlight driver section
8.1
Current generators
The PM6600 is a LEDs driver with six channels (ROWs); each ROW is able to drive multiple
LEDs in series (max. 40 V) and to sink up to 32 mA maximum current, allowing to manage
different kinds of LEDs.
The LEDs current can be set by connecting an external resistor (RRILIM ) between the RILIM
pin and ground. The voltage across the RILIM pin is internally set to 1.2 V and the ROWs
current is proportional to the RILIM current according to the following equation:
Equation 16
IROWx =
KR
RRILIM
Where KR = 998 ± 21 V (± 2.1 %).
The current accuracy between the ROWs of more than one device is, consequently:
Equation 17
∆IROW,MAX =
∆IROW,MIN =
IROW _ KR =1019 − IROW _ KR =998
IROW _ KR =998
IROW _ KR =977 − IROW _ KR =998
IROW _ KR =998
≤ + 2 . 1%
≥ − 2. 1 %
In the table below there are the maximum, typical and minimum IROW values versus the
RRILIM:
Table 7.
IROW values versus RRILIM
RRILIM
IROW @ KR=977
IROW @ KR=998
IROW @ KR=1019
47.0 kΩ
20.79 mA
21.68 mA
21.68 mA
49.9 kΩ
19.58 mA
20.00 mA
20.42 mA
51.0 kΩ
19.16 mA
19.57 mA
19.98 mA
The maximum current mismatch between the ROWs of one device is
± 2 % @ IROWx = 20 mA, according to the formula:
34/43
PM6600
Backlight driver section
Equation 18
∆IROWx,max =
∆IROWx,min =
IROW _ max − IROW _ mean
IROW _ mean
IROW _ min − IROW _ mean
IROW _ mean
≤ + 2%
≥ − 2%
6
IROW _ mean =
∑ IROWi
i=1
6
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 Table 3).
8.2
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 19
DDIM,min = 500ns ⋅ fDIM
For example, at a dimming frequency of 20 kHz, 1% of dimming duty-cycle can be
managed.
The device can manage the condition fDIM = 0 Hz. However, in order to avoid any flickering
issue due to the human eye cutoff frequency, we recommend to use fDIM > 100 Hz (condition
verified with discrete smd leds without any ligth guide).
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.
35/43
Fault management
9
PM6600
Fault management
The main loop keeps the ROW having the lowest voltage drop regulated to about 400 mV.
This value slightly depends on the voltage across the remaining active ROWs. After the softstart sequence, all protections turn active and the voltage across the active current
generators is monitored to detect shorted LEDs.
9.1
FAULT pin
The FAULT pin is an open-collector output, active low, which gives information regarding
faulty conditions eventually detected. This pin can be used either to drive a status LED (with
a series resistor to not exceed 4 mA current) or to warn the host system. The FAULT pin
status is strictly related to the MODE pin setting (see Table 3 for details).
9.2
MODE pin
The MODE pin is a digital input and can be connected to AVCC or SGND in order to choose
the desired fault detection and management. The PM6600 can manage a faulty condition in
two different ways, according to the application needs. Table 3 summarizes how the device
detects and handles the internal protections related to the boost section (Over-Current,
Over-Temperature and Over-Voltage) and to the current generators section (open and
shorted LEDs).
Table 8.
36/43
Faults management summary
FAULT
MODE to GND
MODE to VCC
Internal MOSFET over
current
FAULT pin HIGH
Power-MOS turned OFF
FAULT pin HIGH
Power-MOS turned OFF
Output over voltage
FAULT pin LOW
Device turned OFF Latched
FAULT pin LOW
Device turned OFF Latched
Thermal shutdown
FAULT pin LOW
Device turned OFF Latched
FAULT pin LOW
Device turned OFF Latched
Shorted LEDs on a single
row
FAULT pin LOW
Faulty ROW DISABLED
VTH,FAULT = 8.2 V
FAULT pin LOW
Faulty ROW DISABLED
VTH,FAULT = 8.2 V
Shorted LEDs on more rows
FAULT pin LOW
Device Latched OFF
VTH,FAULT = 8.2 V
FAULT pin LOW
Faulty ROWs DISABLED
VTH,FAULT = 8.2 V
Open row
FAULT pin LOW
Faulty ROW DISABLED
FAULT pin HIGH
Faulty ROW DISABLED
More than one
open rows
FAULT pin LOW
Device Latched OFF
FAULT pin HIGH
Faulty ROWs DISABLED
Open rows plus shorted led
(different rows)
FAULT pin LOW
Device Latched OFF
VTH,FAULT = 8.2 V
FAULT pin LOW
Faulty ROWs DISABLED
VTH,FAULT = 8.2 V
PM6600
9.3
Fault management
Open LED fault
In case a ROW is not connected or a LED fails open, the device has two different behaviors
according to the MODE pin status.
If the MODE pin is high (connected to AVCC), the open ROW is excluded from the control
loop and the device continues to work properly with the remaining ROWs, without asserting
the FAULT pin.
Connecting the MODE pin to SGND, the PM6600 behaves in a different manner: as soon as
one open ROW is detected, the FAULT pin is tied low. In case a second open ROW is
detected, the device is turned off. The internal logic latches this status: to restore the normal
operation, the device must be restarted by toggling the EN pin or performing a Power On
Reset (POR occurs when the voltage at the LDO5 pin falls below the lower UVLO threshold
and subsequently rises above the upper one).
As a consequence, If less than six ROWs are used in the application, the MODE pin must be
set high.
9.4
Shorted LED fault
When a LED is shorted, the voltage across the related current generator increases of an
amount equal to the missing voltage drop of the faulty LED. Since the feedback voltage on
each active generator is constantly compared with a fixed fault threshold VTH,FAULT = 8.2 V,
the device detects the faulty condition and acts according to the MODE pin status.
In case the MODE pin is connected to AVCC, the PM6600 disconnects the ROWs whose
voltage is higher than the threshold and the FAULT pin is tied low. This option is also useful
to avoid undesired triggering of the shorted-LED protection simply due to the high voltage
drop spread across the LEDs.
If the MODE pin is low, when the voltage across one ROW is higher than VTH,FAULT
threshold, the FAULT pin is set low and that ROW is disabled. If the voltage of a second
ROW becomes higher than VTH,FAULT threshold, the device is turned off. The internal logic
latches this status until the EN pin is toggled or a POR is performed.
9.5
Intermittent connection
For intermittent connection it is intended the condition where the flat cable connector from
the leds backlight driver to the leds can have some issues on moving the panel of the
notebook. This kind of issue is represented as an intermittent connection, that means the
physical electrical connection between the ROWx pins of the PM6600 device and the White
LEDs can be open for a while.
The device will detect an open row fault.
There is one possible solution to determine whether the fault is due to the intermittent
connection or to a broken persistent electrical connection (open circuit). Since the device
disables the open rows during the intermittent connection, one possible solution is, on the
customer side, to toggle the EN pin and verify if the fault condition is still present.
In fact, once you disconnect one row, it will result as a off-row (Fault -> open row, latched).
When you connect it again, it is as a shorted led (Vrow higher than the threshold).
This is because the short led detection is still active.
37/43
Fault management
PM6600
If the fault disappears after toggling the EN pin, it means that the connection is again on and
the problem can be detected as a previous intermittent connection.
If the fault persists also after toggling the EN pin, it means that the problem is on the leds
(one or more open leds) or on the flat cable or the cable connector (broken wire).
The resultant Fault Management table will be:
Table 9.
38/43
Intermittent connection faults management summary
FAULT
MODE to GND
MODE to VCC
Internal MOSFET over
current
FAULT pin HIGH
Power-MOS turned OFF
FAULT pin HIGH
Power-MOS turned OFF
Output over voltage
FAULT pin LOW
Device turned OFF Latched
FAULT pin LOW
Device turned OFF Latched
Thermal shutdown
FAULT pin LOW
Device turned OFF Latched
FAULT pin LOW
Device turned OFF Latched
Shorted LED on a single
row
FAULT pin LOW
Faulty ROW DISABLED
VTH,FAULT = 8.2 V
FAULT pin LOW
Faulty ROW DISABLED
VTH,FAULT = 8.2 V
Shorted LEDs on more row
FAULT pin LOW
Device Latched OFF
VTH,FAULT = 8.2 V
FAULT pin LOW
Faulty ROWs DISABLED
VTH,FAULT = 8.2 V
Open row
FAULT pin LOW
Faulty ROW DISABLED
FAULT pin LOW
Faulty ROW DISABLED
More than one
open rows
FAULT pin LOW
Device Latched OFF
FAULT pin LOW
Faulty ROWs DISABLED
Open row plus shorted LED
(different rows)
FAULT pin LOW
Device Latched OFF
VTH,FAULT = 8.2 V
FAULT pin LOW
Faulty ROWs DISABLED
VTH,FAULT = 8.2 V
PM6600
10
Package mechanical data
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a Lead-free second level interconnect. The category of
second Level Interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com.
Table 10.
VFQFPN-24 mechanical data
Dim.
Min
Typ
Max
A
0.80
0.90
1.00
A1
0.00
0.02
0.05
A3
0.20
b
0.18
0.25
0.30
D
3.85
4.00
4.15
D2
2.40
2.50
2.60
E
3.85
4.00
4.15
E2
2.40
2.50
2.60
e
L
ddd
0.50
0.30
0.40
0.50
0.08
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Package mechanical data
Figure 53. VFQFPN-24 mechanical data
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PM6600
PM6600
Package mechanical data
Table 11.
VFQFPN-24 footprint
Dim.
Min
Typ
X
0.28
Y
0.69
ADmax = AEmax
GDmin = GEmin
Max
2.78
2.93
ZDmax = ZEmax
4.31
D2’ = E2’
2.63
Figure 54. VFQFPN-24 footprint
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Revision history
11
PM6600
Revision history
Table 12.
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Document revision history
Date
Revision
Changes
07-Dec-2007
1
Initial release
21-Jan-2008
2
Updated Table 4, Table 5 and Table 6 on page 9
07-Apr-2008
3
Updated Section 3.3 on page 8 and Section 8.2 on page 35
PM6600
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