NXP Semiconductors PCA9959HN-ARD, Руководство пользователя, Страница: 10 / 32

NXP Semiconductors
UM11623
PCA9959HN-ARD evaluation board
Figure 5. Location of the 0 Ω resistors R278 to R281 on the MIMXRT1050-EVK board
5.7 Control bus
The control bus contains three additional control lines (purple color in Figure 4 ): OE
(Output Enable), RESET, and I MAX. OE and RESET are routed to the OE and RESET
inputs of the DUT, directly from Arduino port for the first (or base daughter board) and
through Fuji connectors for the additional boards (pin 5, and pin 7).
The I MAX line controls the switch U4. When U4 is open, the resistor R83 is connected
between the REXT input of the PCA9959HN (pin 39) and ground. R83 sets the maximum
current delivered at the outputs of the DUT at 20 mA. When U4 is closed, R79 is
paralleled with R83, the resulting maximum current increases to 50 mA. For more details
regarding control lines, see the PCA9959 data sheet Table 1 and Table 2.
5.8 LED section
The PCA9959HN features 24 LED drivers (PWM controlled, current sink sources). Four
RGB LEDs are allocated to the first outputs (LED0 to LED11). The outputs LED12 to
LED23 drives white LEDs. The LEDs can be disconnected from the IC outputs with
jumpers.
The RGB LED D16 has jumpers connected in parallel for short testing. The jumpers J76
to J81 allow the user to redirect the corresponding output lines of D16 and D17 RGB
LEDs from the onboard LEDs to the RGB LED external connectors (J21 and J26). Using
the connectors, the user can easily attach external LEDs for testing. In the same manner,
the corresponding lines of white LEDs D14 and D15 can be redirected with J82 and J83
jumpers to white LED external connectors J23 and J25.
5.9 Power distribution
The power supply is provided from the EVK mother board for the first card, and through
the Fuji connectors for all additional cards. There are two power rails: 3.3 V and 5.0 V.
The main power consumption is from the 5.0 V power rail. The necessary current for one
daughter board when all LEDs are turned ON is 1.2 A (I MAX: 50 mA). Due to current
limitations, the number of boards installed in the stack is limited. The limitation depends
UM11623 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2021. All rights reserved.
User manual Rev. 1 — 21 May 2021
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