PCA9745B
16-channel SPI serial bus 57 mA/20 V constant current LED
driver
Rev. 1 — 16 June 2016
Product data sheet
1. General description
The PCA9745B is a daisy-chain SPI-compatible 4-wire serial bus controlled 16-channel
constant current LED driver optimized for dimming and blinking 57 mA
Red/Green/Blue/Amber (RGBA) LEDs in amusement products. Each LED output has its
own 8-bit resolution (256 steps) fixed frequency individual PWM controller that operates at
31.25 kHz with a duty cycle that is adjustable from 0 % to 100 % to allow the LED to be
set to a specific brightness value. An additional 8-bit resolution (256 steps) group PWM
controller has both a fixed frequency of 122 Hz and an adjustable frequency between
15 Hz to once every 16.8 seconds with a duty cycle that is adjustable from 0 % to 99.6 %
that is used to either dim or blink all LEDs with the same value.
Each LED output can be off, on (no PWM control), set at its individual PWM controller
value or at both individual and group PWM controller values. The PCA9745B operates
with a supply voltage range of 3 V to 5.5 V and the constant current sink LED outputs
allow up to 20 V for the LED supply. The output peak current is adjustable with an 8-bit
linear DAC from 225
A
to 57 mA.
Gradation control for all current sources is achieved via the 4-wire serial bus interface and
allows user to ramp current automatically without MCU intervention. 8-bit DACs are
available to adjust brightness levels for each LED current source. There are four
selectable gradation control groups and each group has independently four registers to
control ramp-up and ramp-down rate, step time, hold ON/OFF time and final hold ON
output current. Two gradation operation modes are available for each group, one is single
shot mode (output pattern once) and the other is continuous mode (output pattern repeat).
Each channel can be set to either gradation mode or normal mode and assigned to any
one of these four gradation control groups.
This device has built-in open, short load and overtemperature detection circuitry. The error
information from the corresponding register can be read via the 4-wire serial bus.
Additionally, a thermal shutdown feature protects the device when internal junction
temperature exceeds the limit allowed for the process.
The PCA9745B device is designed to use 4-wire read/write serial bus with higher data
clock frequency (up to 25 MHz).
The active LOW output enable input pin (OE) blinks all the LED outputs and can be used
to externally PWM the outputs, which is useful when multiple devices need to be dimmed
or blinked together without using software control.
NXP Semiconductors
PCA9745B
16-channel SPI serial bus 57 mA/20 V constant current LED driver
2. Features and benefits
16 LED drivers. Each output programmable at:
Off
On
Programmable LED brightness
Programmable group dimming/blinking mixed with individual LED brightness
Programmable LED output delay to reduce EMI and surge currents
Gradation control for all channels
Each channel can assign to one of four gradation control groups
Programmable gradation time and rate for ramp-up and/or ramp-down operations
Programmable step time (6-bit) from 0.5 ms (minimum) to 512 ms (maximum)
Programmable hold-on time after ramp-up and hold-off time after ramp-down (3-bit)
from 0 s to 6 s
Programmable final ramp-up and hold-on current
Programmable brightness current output adjustment, either linear or exponential
curve
16 constant current output channels can sink up to 57 mA, tolerate up to 20 V when
OFF
Output current adjusted through an external resistor (REXT input)
Output current accuracy
4
% between output channels
6
% between PCA9745B devices
Open/short load/overtemperature detection mode to detect individual LED errors
4-wire serial bus interface with 25 MHz data clock rate
256-step (8-bit) linear programmable brightness per LED output varying from fully off
(default) to maximum brightness fully ON using a 31.25 kHz PWM signal
256-step group brightness control allows general dimming (using a 122 Hz PWM
signal) from fully off to maximum brightness (default)
256-step group blinking with frequency programmable from 15 Hz to 16.8 s and duty
cycle from 0 % to 99.6 %
Active LOW Output Enable (OE) input pin allows for hardware blinking and dimming of
the LEDs
8 MHz internal oscillator requires no external components
Internal power-on reset
Noise filter on SDI/SCLK inputs
No glitch on LEDn outputs on power-up
Low standby current
Operating power supply voltage (V
DD
) range of 3 V to 5.5 V
5.5 V tolerant inputs on non-LED pins
40 C
to +105
C
operation
ESD protection exceeds 4 kV HBM per JESD22-A114
Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
Packages offered: HTSSOP28
PCA9745B
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2016. All rights reserved.
Product data sheet
Rev. 1 — 16 June 2016
2 of 48
NXP Semiconductors
PCA9745B
16-channel SPI serial bus 57 mA/20 V constant current LED driver
3. Applications
Amusement products
RGB or RGBA LED drivers
LED status information
LED displays
LCD backlights
Keypad backlights for cellular phones or handheld devices
Fade-in and fade-out for breathlight control
Automotive lighting (PCA9745BTW/Q900)
4. Ordering information
Table 1.
Ordering information
Topside mark
PCA9745BTW
Package
Name
PCA9745BTW
HTSSOP28
Description
Version
plastic thermal enhanced thin shrink small
SOT1172-3
outline package; 28 leads; body width 4.4 mm;
lead pitch 0.65 mm; exposed die pad
plastic thermal enhanced thin shrink small
SOT1172-3
outline package; 28 leads; body width 4.4 mm;
lead pitch 0.65 mm; exposed die pad
Type number
PCA9745BTW/Q900
[1]
PCA9745BTW
HTSSOP28
[1]
AEC-Q100 compliant.
4.1 Ordering options
Table 2.
Ordering options
Orderable part
number
PCA9745BTWJ
Package
Packing method
Minimum
order
quantity
Temperature
Type number
PCA9745BTW
HTSSOP28 Reel 13" Q1/T1
2500
*Standard mark SMD
T
amb
=
40 C
to +105
C
T
amb
=
40 C
to +105
C
PCA9745BTW/Q900 PCA9745BTW/Q900J HTSSOP28 Reel 13" Q1/T1
2500
*Standard mark SMD
PCA9745B
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2016. All rights reserved.
Product data sheet
Rev. 1 — 16 June 2016
3 of 48
NXP Semiconductors
PCA9745B
16-channel SPI serial bus 57 mA/20 V constant current LED driver
5. Block diagram
REXT
I/O
REGULATOR
LED0
LED1
LED14
LED15
PCA9745B
DAC0
SCLK
SDI
CS
SDO
INPUT FILTER
individual LED
current setting
8-bit DACs
DAC1
4-WIRE
SERIAL BUS
CONTROL
POWER-ON
RESET
DAC
14
DAC
15
V
DD
V
SS
RESET
OUTPUT DRIVER, DELAY CONTROL,
AND THERMAL SHUTDOWN
INPUT
FILTER
PWM
REGISTER X
BRIGHTNESS
CONTROL
LED STATE
SELECT
REGISTER
GRADATION
CONTROL
÷ 256
8 MHz
OSCILLATOR
31.25 kHz
GRPFREQ
REGISTER
MUX/
CONTROL
GRPPWM
REGISTER
'0' – permanently OFF
'1' – permanently ON
DIM CLOCK
OE
aaa-019148
Dim repetition rate = 122 Hz
Blink repetition rate = 15 Hz to every 16.8 seconds
Fig 1.
Block diagram of PCA9745B
PCA9745B
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2016. All rights reserved.
Product data sheet
Rev. 1 — 16 June 2016
4 of 48
NXP Semiconductors
PCA9745B
16-channel SPI serial bus 57 mA/20 V constant current LED driver
6. Pinning information
6.1 Pinning
REXT
V
SS
SDO
CS
OE
LED0
LED1
LED2
LED3
1
2
3
4
5
6
7
8
9
(1)
28 V
DD
27 SDI
26 SCLK
25 RESET
24 V
SS
23 LED15
22 LED14
21 LED13
20 LED12
19 V
SS
18 LED11
17 LED10
16 LED9
15 LED8
aaa-019149
PCA9745BTW
V
SS
10
LED4 11
LED5 12
LED6 13
LED7 14
(1) Thermal pad; connected to V
SS
.
Fig 2.
Pin configuration for HTSSOP28
6.2 Pin description
Table 3.
Symbol
REXT
SDO
CS
OE
LED0
LED1
LED2
LED3
LED4
LED5
LED6
LED7
LED8
LED9
LED10
LED11
LED12
LED13
PCA9745B
Pin description
Pin
1
3
4
5
6
7
8
9
11
12
13
14
15
16
17
18
20
21
Type
I
O
I
I
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Description
current set resistor input; resistor to ground
serial data output
active LOW chip select
active LOW output enable for LEDs
LED driver 0
LED driver 1
LED driver 2
LED driver 3
LED driver 4
LED driver 5
LED driver 6
LED driver 7
LED driver 8
LED driver 9
LED driver 10
LED driver 11
LED driver 12
LED driver 13
© NXP B.V. 2016. All rights reserved.
All information provided in this document is subject to legal disclaimers.
Product data sheet
Rev. 1 — 16 June 2016
5 of 48
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