and a 6-bit (64-step) ±50% correction register. All controls
are programmable via a simple serial data interface. Three
banks of 16-channels each can be configured such that
they operate 120° out-of-phase with each other.
The LT8500 features two diagnostic information flags:
synchronization error and open LED. The flags are sent,
with additional state information, on the serial data interface
during status read back. The 50MHz cascadable serial data
interface includes buffering and skew-balancing, making
the chip suitable for PWM intensive applications such
as large screen LCD dynamic backlighting and mono-,
multi- and full-color LED displays. The LT8500 is also
ideally suited to control three LT3595A LED drivers.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
n
n
n
n
n
3V to 5.5V Input Voltage
48 Independent PWM Outputs
TTL/CMOS Logic 50MHz Serial Data Interface
12-Bit (4096 Steps) PWM Width Resolution
6-Bit (64 Steps) PWM Correction
(±50% of Programmed PWM Width)
Up to 6.1kHz PWM Frequency (PWMCK = 25MHz)
Phase-Shift Option Reduces Switching Noise
Directly Controls Three LT3595A 16-Channel
LED Drivers
Diagnostic Information: Sync Error/Open LED Flags
56-Pin (5mm
×
9mm
×
0.75mm) QFN Package
applicaTions
n
n
n
n
n
n
n
Large Screen Display LED Backlighting
Mono-, Multi-, Full-Color LED Displays
LED Billboards and Signboards
Motor Control
Industrial Control
Automated Test Equipment
Robotics
Typical applicaTion
48 PWM OUTPUTS
• • • • •
5-WIRE
SERIAL
DATA
INTERFACE
OSC
PWM[48:1]
SDI
SDO
SCKI
SCK0
LDIBLANK
LT8500 (1)
PWMCK
OPENLED
48 PWM OUTPUTS
• • • • •
PWM[48:1]
SDI
SDO
SCKI
SCK0
LDIBLANK
LT8500 (2)
PWMCK
OPENLED
••••
••••
48 PWM OUTPUTS
• • • • •
PWM[48:1]
SDI
SDO
SCKI
SCK0
LDIBLANK
LT8500 (N)
PWMCK
OPENLED
DIAGNOSTIC
CIRCUIT
••••
••••
••••
8500 TA01a
8500f
1
LT8500
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
PWM13
PWM14
PWM15
PWM16
PWM10
PWM47
PWM11
46 PWM12
45 PWM5
44 PWM6
43 PWM7
42 PWM8
41 LDIBLANK
40 SDI
39 PWMCK
57
GND
38 SCKO
37 VCC
36 SCKI
35 SDO
34
OPENLED
33 PWM33
32 PWM34
31 PWM35
30 PWM36
29 PWM45
19 20 21 22 23 24 25 26 27 28
PWM39
PWM38
PWM37
PWM44
PWM43
PWM42
PWM41
PWM48
PWM46
PWM2
PWM3
PWM4
PWM9
V
CC
............................................................... –0.3V to 6V
SDI, SCKI, PWMCK,
OPENLED,
LDIBLANK ......... –0.3V to Lesser of 6V and (V
CC
+ 0.3V)
Operating Junction Temperature Range
(Note 2) .................................................. –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
56 55 54 53 52 51 50 49 48 47
PWM1 1
PWM24 2
PWM23 3
PWM22 4
PWM21 5
PWM28 6
PWM27 7
PWM26 8
PWM25 9
PWM32 10
PWM31 11
PWM30 12
PWM29 13
PWM20 14
PWM19 15
PWM18 16
PWM17 17
PWM40 18
UHH PACKAGE
56-LEAD (5mm × 9mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 35°C/W,
θ
JC
= 5°C/W
EXPOSED PAD (PIN 57) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LT8500EUHH#PBF
LT8500IUHH#PBF
TAPE AND REEL
LT8500EUHH#TRPBF
LT8500IUHH#TRPBF
PART MARKING*
8500
8500
PACKAGE DESCRIPTION
56-Lead (5mm
×
9mm) Plastic QFN
56-Lead (5mm
×
9mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
8500f
2
LT8500
elecTrical characTerisTics
SYMBOL
Supply
V
CC
V
CC
Operating Voltage
Input Logic Levels
High Level Voltage
Low Level Voltage
Input Current
OPENLED
Pull-Up Resistor
Input Capacitance (Note 4)
SDO, SCKO Output Voltages
High Level Voltage
Low Level Voltage
PWM [48:1] Output Voltages
High Level Voltage
Low Level Voltage
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.3V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
3.0
TYP
MAX
5.5
UNIT
V
Digital Inputs: SCKI, SDI, LDIBLANK,
OPENLED,
PWMCK
V
IH
V
IL
I
IN
R
PU
C
IN
V
CC
= 5V
V
CC
= 3.3V
V
CC
= 5V
V
CC
= 3.3V
Pin Voltage = V
CC
or GND Excluding
OPENLED
V
CC
= 5.5V
Pin to GND
l
l
l
l
4.0
2.7
1.0
0.6
1
100
3
130
V
V
V
V
µA
kΩ
pF
–1
70
Digital Outputs: SCKO, SDO, PWM[48:1]
V
OH
V
OL
V
OH
V
OL
I
OUT
= –6mA, V
CC
= 5V
I
OUT
= –3mA, V
CC
= 3.3V
I
OUT
= 6mA, V
CC
= 5V
I
OUT
= 3mA, V
CC
= 3.3V
I
OUT
= –3mA, V
CC
= 5V
I
OUT
= –1.5mA, V
CC
= 3.3V
I
OUT
= 3mA, V
CC
= 5V
I
OUT
= 1.5mA, V
CC
= 3.3V
l
l
l
l
l
l
l
l
4.0
2.7
1.0
0.6
V
V
V
V
V
V
V
V
4.0
2.7
1.0
0.6
TiMing characTerisTics
SYMBOL
f
SCKI
f
PWMCK
t
WH-SCKI
t
WL-SCKI
t
WH-LDI
t
WH-BLANK
t
SU-SDI
t
HD-SDI
t
SU-LDI
t
HD-LDI
t
PD-SDO
t
PD-SCK
t
HD-SDO
t
DC-SCK
PARAMETER
Data Shift Clock Frequency
PWMCK Clock Frequency
Minimum SCKI High Time (Note 3)
Minimum SCKI Low Time (Note 3)
LDIBLANK Pulse Duration
(LDI Function)
LDIBLANK Pulse Duration
(BLANK Function)
SDI-SCKI Setup Time (Note 3)
SCKI-SDI Hold Time (Note 3)
SCKI-LDIBLANK Setup Time (Note 3)
LDIBLANK-SCKI Hold Time (Note 3)
SCKI-SDO Propagation Delay (Note 3)
SCKI-SCKO Propagation Delay (Note 3)
SCKO-SDO Hold Time (Note 3)
SCKI-SCKO Duty Cycle Change (Note 4)
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.3V, and all inputs are rail-to-rail unless otherwise noted.
CONDITIONS
SCKI
↑
– SCKI
↑
(Figure 4)
PWMCK
↑
– PWMCK
↑
(Figure 5)
SCKI = High
SCKI = Low
LDIBLANK = High (Figure 4)
LDIBLANK = High (Figure 4)
SDI
↑↓
– SCKI
↑
(Figure 4)
SCKI
↑
– SDI
↑↓
(Figure 4)
SCKI
↑
– LDIBLANK
↑
(Figure 4)
SCKI 50% Duty Cycle
LDIBLANK
↓
– SCKI
↑
(Figure 4)
SCKI
↑
– SDO
↑↓
(Figure 4)
SCKI
↑
– SCKO
↑
(Figure 4)
SCKO
↑
– SDO
↑↓
(Figure 4)
Difference Between SCKI = High Time
and SCKO = High Time, C
LOAD
= 25pF
l
l
l
l
l
l
l
l
l
l
l
MIN
TYP
MAX
50
25
UNIT
MHz
MHz
ns
ns
2
2
8
50,000
3
1.75
10
5
15
10
2.75
–0.2
25
20
5,000
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
8500f
3
LT8500
TiMing characTerisTics
SYMBOL
t
PD-PWM
t
R-SDO
t
F-SDO
t
R-PWM
t
F-PWM
PARAMETER
PWMCK-PWM[48:1] Propagation Delay
(Note 3)
SDO, SCKO Rise Time (Note 4)
SDO, SCKO Fall Time (Note 4)
PWM[48:1] Rise Time (Note 4)
PWM[48:1] Fall Time (Note 4)
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.3V, and all inputs are rail-to-rail unless otherwise noted.
CONDITIONS
PWMCK
↑
– PWM
↑↓
(Figure 5)
C
LOAD
= 25pF 30% to 70%
,
C
LOAD
= 25pF 70% to 30%
,
C
LOAD
= 25pF 30% to 70%
,
C
LOAD
= 25pF 70% to 30%
,
l
MIN
TYP
32
2
2
12
12
MAX
50
UNIT
ns
ns
ns
ns
ns
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LT8500E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT8500I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 3:
Propagation delays, setup/hold times and hi times are measured
from 50% to 50%.
Note 4:
This parameter is correlated to lab measurements and is not
subject to production testing.
TiMing DiagraM
t
WH-LDI
t
SU-SDI
t
HD-SDI
1/f
SCKI
t
SU-LDI
t
HD-LDI
t
WH-SCKI
t
WL-SCKI
SCKI
SDI
LDIBLANK
SCKO
SDO
8500 TD01
t
PD-SDO
t
PD-SCK
t
HD-SDO
8500f
4
LT8500
For the I
CC
vs V
CC
Graphs, the Following Conditions
Apply: 23pF Load on SCKO. PWM Outputs Enabled: Duty Cycle = 1365/4096, 10pF Average Load on PWMs.
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