PCA9685
16-channel, 12-bit PWM Fm+ I
2
C-bus LED controller
Rev. 02 — 16 July 2009
Product data sheet
1. General description
The PCA9685 is an I
2
C-bus controlled 16-channel LED controller optimized for LCD
Red/Green/Blue/Amber (RGBA) color backlighting applications. Each LED output has its
own 12-bit resolution (4096 steps) fixed frequency individual PWM controller that operates
at a programmable frequency from a typical of 40 Hz to 1000 Hz with a duty cycle that is
adjustable from 0 % to 100 % to allow the LED to be set to a specific brightness value.
All outputs are set to the same PWM frequency.
Each LED output can be off or on (no PWM control), or set at its individual PWM controller
value. The LED output driver is programmed to be either open-drain with a 25 mA current
sink capability at 5 V or totem pole with a 25 mA sink, 10 mA source capability at 5 V. The
PCA9685 operates with a supply voltage range of 2.3 V to 5.5 V and the inputs and
outputs are 5.5 V tolerant. LEDs can be directly connected to the LED output (up to
25 mA, 5.5 V) or controlled with external drivers and a minimum amount of discrete
components for larger current or higher voltage LEDs.
The PCA9685 is in the new Fast-mode Plus (Fm+) family. Fm+ devices offer higher
frequency (up to 1 MHz) and more densely populated bus operation (up to 4000 pF).
Although the PCA9635 and PCA9685 have many similar features, the PCA9685 has
some unique features that make it more suitable for applications such as LCD backlighting
and Ambilight:
•
The PCA9685 allows staggered LED output on and off times to minimize current
surges. The on and off time delay is independently programmable for each of the
16 channels. This feature is not available in PCA9635.
•
The PCA9685 has 4096 steps (12-bit PWM) of individual LED brightness control. The
PCA9635 has only 256 steps (8-bit PWM).
•
When multiple LED controllers are incorporated in a system, the PWM pulse widths
between multiple devices may differ if PCA9635s are used. The PCA9685 has a
programmable prescaler to adjust the PWM pulse widths of multiple devices.
•
The PCA9685 has an external clock input pin that will accept user-supplied clock
(50 MHz max.) in place of the internal 25 MHz oscillator. This feature allows
synchronization of multiple devices. The PCA9635 does not have external clock input
feature.
•
Like the PCA9635, PCA9685 also has a built-in oscillator for the PWM control.
However, the frequency used for PWM control in the PCA9685 is adjustable from
about 40 Hz to 1000 Hz as compared to the typical 97.6 kHz frequency of the
PCA9635. This allows the use of PCA9685 with external power supply controllers. All
bits are set at the same frequency.
•
The Power-On Reset (POR) default state of LEDn output pins is LOW in the case of
PCA9685. It is HIGH for PCA9635.
NXP Semiconductors
PCA9685
16-channel, 12-bit PWM Fm+ I
2
C-bus LED controller
The active LOW Output Enable input pin (OE) allows asynchronous control of the LED
outputs and can be used to set all the outputs to a defined I
2
C-bus programmable logic
state. The OE can also be used to externally ‘pulse width modulate’ the outputs, which is
useful when multiple devices need to be dimmed or blinked together using software
control.
Software programmable LED All Call and three Sub Call I
2
C-bus addresses allow all or
defined groups of PCA9685 devices to respond to a common I
2
C-bus address, allowing
for example, all red LEDs to be turned on or off at the same time or marquee chasing
effect, thus minimizing I
2
C-bus commands. Six hardware address pins allow up to
62 devices on the same bus.
The Software Reset (SWRST) General Call allows the master to perform a reset of the
PCA9685 through the I
2
C-bus, identical to the Power-On Reset (POR) that initializes the
registers to their default state causing the outputs to be set LOW. This allows an easy and
quick way to reconfigure all device registers to the same condition via software.
2. Features
I
16 LED drivers. Each output programmable at:
N
Off
N
On
N
Programmable LED brightness
N
Programmable LED turn-on time to help reduce EMI
I
1 MHz Fast-mode Plus compatible I
2
C-bus interface with 30 mA high drive capability
on SDA output for driving high capacitive buses
I
4096-step (12-bit) linear programmable brightness per LED output varying from fully
off (default) to maximum brightness
I
LED output frequency (all LEDs) typically varies from 40 Hz to 1000 Hz (Default of 1Eh
in PRE_SCALE register results in a 200 Hz refresh rate with oscillator clock of
25 MHz.)
I
Sixteen totem pole outputs (sink 25 mA and source 10 mA at 5 V) with software
programmable open-drain LED outputs selection (default at totem pole). No input
function.
I
Output state change programmable on the Acknowledge or the STOP Command to
update outputs byte-by-byte or all at the same time (default to ‘Change on STOP’).
I
Active LOW Output Enable (OE) input pin. LEDn outputs programmable to logic 1,
logic 0 (default at power-up) or ‘high-impedance’ when OE is HIGH.
I
6 hardware address pins allow 62 PCA9685 devices to be connected to the same
I
2
C-bus
I
Toggling OE allows for hardware LED blinking
I
4 software programmable I
2
C-bus addresses (one LED All Call address and three LED
Sub Call addresses) allow groups of devices to be addressed at the same time in any
combination (for example, one register used for ‘All Call’ so that all the PCA9685s on
the I
2
C-bus can be addressed at the same time and the second register used for three
different addresses so that
1
⁄
3
of all devices on the bus can be addressed at the same
time in a group). Software enable and disable for these I
2
C-bus address.
I
Software Reset feature (SWRST General Call) allows the device to be reset through
the I
2
C-bus
PCA9685_2
© NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 02 — 16 July 2009
2 of 50
NXP Semiconductors
PCA9685
16-channel, 12-bit PWM Fm+ I
2
C-bus LED controller
I
I
I
I
I
I
I
I
I
I
I
I
25 MHz typical internal oscillator requires no external components
External 50 MHz (max.) clock input
Internal power-on reset
Noise filter on SDA/SCL inputs
Edge rate control on outputs
No output glitches on power-up
Supports hot insertion
Low standby current
Operating power supply voltage range of 2.3 V to 5.5 V
5.5 V tolerant inputs
−40 °C
to +85
°C
operation
ESD protection exceeds 2000 V HBM per JESD22-A114, 200 V MM per
JESD22-A115 and 1000 V CDM per JESD22-C101
I
Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
I
Packages offered: TSSOP28, HVQFN28
3. Applications
I
I
I
I
I
RGB or RGBA LED drivers
LED status information
LED displays
LCD backlights
Keypad backlights for cellular phones or handheld devices
4. Ordering information
Table 1.
Ordering information
Topside mark
PCA9685PW
PCA9685PW
PCA9685BS
Package
Name
PCA9685PW
PCA9685PW/Q900
[1]
PCA9685BS
TSSOP28
TSSOP28
HVQFN28
Description
plastic thin shrink small outline package;
28 leads; body width 4.4 mm
plastic thin shrink small outline package;
28 leads; body width 4.4 mm
plastic thermal enhanced very thin quad flat
package; no leads; 28 terminals;
body 6
×
6
×
0.85 mm
Version
SOT361-1
SOT361-1
SOT788-1
Type number
[1]
PCA9685PW/Q900 is AEC-Q100 compliant. Contact
i2c.support@nxp.com
for PPAP.
PCA9685_2
© NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 02 — 16 July 2009
3 of 50
NXP Semiconductors
PCA9685
16-channel, 12-bit PWM Fm+ I
2
C-bus LED controller
5. Block diagram
A0
A1
A2
A3
A4
A5
PCA9685
SCL
SDA
I
2
C-BUS
CONTROL
V
DD
V
SS
LED
STATE
SELECT
REGISTER
PWM
REGISTER X
BRIGHTNESS
CONTROL
MUX/
CONTROL
POWER-ON
RESET
INPUT FILTER
V
DD
PRESCALE
25 MHz
OSCILLATOR
EXTCLK
LEDn
CLOCK
SWITCH
'0' – permanently OFF
'1' – permanently ON
OE
002aac824
Remark:
Only one LED output shown for clarity.
Fig 1.
Block diagram of PCA9685
PCA9685_2
© NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 02 — 16 July 2009
4 of 50
NXP Semiconductors
PCA9685
16-channel, 12-bit PWM Fm+ I
2
C-bus LED controller
6. Pinning information
6.1 Pinning
25 V
DD
24 SDA
28 A2
27 A1
A2
A3
A4
LED0
LED1
LED2
LED3
3
4
5
6
7
8
9
26 SCL
25 EXTCLK
24 A5
23 OE
22 LED15
21 LED14
20 LED13
19 LED12
18 LED11
17 LED10
16 LED9
A3
A4
LED0
LED1
LED2
LED3
LED4
1
2
3
4
5
6
7
LED7 10
V
SS
11
LED8 12
LED9 13
LED10 14
8
9
26 A0
terminal 1
index area
23 SCL
A1
2
22 EXTCLK
21 A5
20 OE
19 LED15
18 LED14
17 LED13
16 LED12
15 LED11
002aad236
A0
1
28 V
DD
27 SDA
PCA9685PW
PCA9685PW/Q900
PCA9685BS
LED4 10
LED5 11
LED6 12
LED7 13
V
SS
14
002aac825
LED5
15 LED8
Transparent top view
Fig 2.
Pin configuration for TSSOP28
Fig 3.
Pin configuration for HVQFN28
6.2 Pin description
Table 2.
Symbol
A0
A1
A2
A3
A4
LED0
LED1
LED2
LED3
LED4
LED5
LED6
LED7
V
SS
LED8
LED9
LED10
LED11
PCA9685_2
Pin description
Pin
TSSOP28
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
HVQFN28
26
27
28
1
2
3
4
5
6
7
8
9
10
11
[1]
12
13
14
15
I
I
I
I
I
O
O
O
O
O
O
O
O
power supply
O
O
O
O
address input 0
address input 1
address input 2
address input 3
address input 4
LED driver 0
LED driver 1
LED driver 2
LED driver 3
LED driver 4
LED driver 5
LED driver 6
LED driver 7
supply ground
LED driver 8
LED driver 9
LED driver 10
LED driver 11
© NXP B.V. 2009. All rights reserved.
Type
Description
Product data sheet
Rev. 02 — 16 July 2009
LED6
5 of 50
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