and a 6-bit (64-step) ±50% correction register. All con-
trols 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 inter-
face during status read back. The 50MHz cascadable serial
data interface includes buffering and skew-balancing, mak-
ing 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.
All registered trademarks and trademarks are the property of their respective owners.
n
n
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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 (6mm
×
6mm
×
0.78mm) TLA 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
Rev C
Document Feedback
For more information
www.analog.com
1
LT8500
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
PWM915
PWM13
PWM14
PWM16
PWM10
PWM11
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
PWM2
PWM24
PWM22
PWM23
PWM26
PWM25
PWM31
PWM20
PWM29
PWM17
PWM40
PWM1
PWM21
PWM27
PWM28
PWM32
PWM30
PWM19
PWM18
A1 A40 A39 A38 A37 A36 A35 A34 A33 A32 A31
A2
A3
A4
A5
A6
A7
A8
A9
A10
B1
B2
B3
B4
B5
B6
B7
B8
57
GND
B16
B15
B14
B13
B12
B11
B10
B9
A30
A29
A28
A27
A26
A25
A24
A23
A22
PWM5
PWM8
SDI
SDKO
SCKI
OPENLED
PWM35
PWM45
PWM12
PWM7
PWM6
LDIBLANK
PWMCK
V
CC
SDO
PWM33
PWM34
PWM36
PWM46
A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21
PWM39
PWM37
PWM38
PWM44
PWM43
PWM42
PWM41
PWM48
PWM47
TJ PACKAGE
56-LEAD PLASTIC TLA QFN (6mm × 6mm)
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
LT8500ETJ#PBF
LT8500ITJ#PBF
TAPE AND REEL
LT8500ETJ#TRPBF
LT8500ITJ#TRPBF
PART MARKING*
LT8500TJ
LT8500TJ
PACKAGE DESCRIPTION
56-Lead (6mm
×
6mm) Plastic TLAQFN
56-Lead (6mm
×
6mm) Plastic TLAQFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult ADI Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
Rev C
2
For more information
www.analog.com
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
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.
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
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)
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)
l
l
l
l
l
l
l
l
l
l
l
TIMING CHARACTERISTICS
MIN
TYP
MAX
50
25
UNIT
MHz
MHz
ns
ns
2
2
8
50,000
3
1.75
10
5
15
10
2.75
25
20
5,000
ns
ns
ns
ns
ns
ns
ns
ns
ns
Rev C
For more information
www.analog.com
3
LT8500
TIMING CHARACTERISTICS
SYMBOL
t
DC-SCK
t
PD-PWM
t
R-SDO
t
F-SDO
t
R-PWM
t
F-PWM
PARAMETER
SCKI-SCKO Duty Cycle Change (Note 4)
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
Difference Between SCKI = High Time
and SCKO = High Time, C
LOAD
= 25pF
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
–0.2
32
2
2
12
12
MAX
UNIT
ns
50
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
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