Scalable Evaluation Board with NCV7685 Twelve Channels LED Linear Current Drivers User's Manual
NCV7685 Variants
- NCV7685LOWR1GEVB
- NCV7685MIDR1GEVB
- NCV7685HIGH1GEVB
- NCV7685BCMR1GEVB
Introduction
The Scalable reference design kit / evaluation board demonstrates the Rear Combination Lamp Application with the multiple NCV7685 LED linear current drivers. Three different variants (Low, Mid, High−End) represent different target platforms. Using the same LED display for every variant, different performance can be attained.
On−board buck converter creates constant voltage on the top of the LEDs to minimize power dissipation on the devices. The boards contain four to six NCV7685 drivers, which are used for four different functions: Tail, Stop, Turn, and Reverse. The amber color of the LEDs emulates TAIL / STOP functionality. Yellow color is for the TURN signal and white color for Reverse function.
The scalable boards have to be controlled/powered via BCM (Body Control Module) NCV7685BCMR1GEVB. The BCM module can activate the appropriate function and the eventual diagnostic can be read−back. The BCM is compatible with all three EVB variants.
Evaluation Board Features
- Wide range of supply voltage: 6 to 18 V
- LED display with 5 x 12 + 4 LEDs
- V voltage 4.3 - 4.9 V
- VSTRING voltage 4.3 - 4.9 V
- Default LED string current: 10 mA (Nominal current for TAIL), 50 mA (Nominal current for STOP), 50 mA (Nominal current for TURN), 3 x 25 mA (Nominal current for REV)
- Fail Safe capability emulated by CONF pin
- One LED Open−load, emulation jumper
- Supply Diagnostic LEDs
- Test points for every signal
Table 1. ABSOLUTE MAXIMUM RATINGS
| Rating | Value | Unit |
|---|---|---|
| Supply Voltage(VBAT) | -28 to +28 | V |
| LED Strings Current | 3.3 | A |
| Junction Temperature(NCV7685) | -40 to +150 | ℃ |
| Junction Temperature(Advanced Power TOPLED OSRAM LED) | -40 to +125 | ℃ |
| Ambient Temperature | -40 to +105 | ℃ |
Table 2. RECOMMENDED BOARD OPERATING CONDITIONS
| Rating | Value | Unit |
|---|---|---|
| Supply Voltage(Vbat) | 6 to 18 | V |
| Rated LED string currents per one LED | 10/50/75 | mA |
| Auxiliary Circuits Consumption | ≈32-47 | mA |
| Ambient Temperature | -40 to +105 | ℃ |
Table 3. INTERFACE FUNCTION DESCRIPTION
| Connector Name | Connector Type | Description/Function |
|---|---|---|
| Supply | DC POWER,2.5MM | Input supply connector, DC 6-18V |
| CON-FCN | 1x6 header | Function activation connector |
| CON-KEY | 1x2 header | Key Switch Connector |
| CON_DIAG | 1x5 header | Diagnostic connector |
| OL1 | 1x2 header | Open Load emulation jumper |
| ISET | Test Point | Iset pin of the IC10 |
| DgEN | Test Point | DiagEN pin of IC10 |
| DIAG | Test Point | DIAG pin of IC10 |
| SDA | Test Point | I2C Data test point |
| SCL | Test Point | I2C Clock test point |
| VDD | Test Point | VDD supply test point |
| GND | Test Point | GND test point |
| VCC | Test Point | Output VCC reference of the IC10 |
| VS | Test Point | VS supply of the IC10 |
| SW | Button | MCU reset button |
| ScopeGND1, ScopeGND2 | Wire Bridge | Ground wire |
| JRLS | 10pin JTAG header | JTAG header for RSL10 programming |
Getting Started
The Scalable Evaluation board platform contains three variants controlled by one BCM module. The BCM module is universal and can be connected to every EVB variant: Low−End, Mid−End, or High−End EVB.
The BCM board is supplied through a standard 5.5 x 2.5 mm DC connector. Supply voltage range must be from 6 to 18 V. Below 6 V, the current through the LEDs starts decreasing. For supply voltage above 18 V, board temperature can be a limitation. The Function and Diagnostic connectors must be connected. For the High−End version, the Key connector must also be interconnected with the EVB board. Onboard activation switches (or button for STOP) activate the appropriate function. The green indication LED shows the status of the switches. The red LEDs indicate any faults reported from the EVB boards.
NCV7685LOWR1GEVB
The Low−end variant comes with four NCV7685 devices. Each device controls an individual function (TAIL, TURN, REVERSE, STOP). The REVERSE contains only four white LEDs, each requiring three outputs of 25 mA to drive.
Low-End Control Overview
| TAIL | STOP | REVERSE | TURN |
|---|---|---|---|
| OFF | ON | OFF | ON |
| 1 segment | 1 segment | ||
| 12 LED/segm. | 12 LED/segm. |
NCV7685MIDR1GEVB
The Mid−end variant is similar to the Low−end variant, with the addition of an RSL10 microcontroller to control the TURN LED driver. When the TURN signal is activated, an animated turn indicator effect is played.
Mid-End Control Overview
| TAIL | STOP | REVERSE | TURN |
|---|---|---|---|
| OFF | ON | OFF | ON |
| PWM | |||
| 1 segment | 1 segment | ||
| 12 LED/segm. | 12 LED/segm. |
NCV7685HIGHGEVB
The High−end variant contains six NCV7685 devices, each controlling an individual LED. If the MCU is reset or is not responding, all devices will switch to standalone mode operation from I2C mode. In Fail Safe mode, the board performs as the Low−end variant.
Schematic Diagrams
- Figure 12: Schematic of the NCV7685LOWR1GEVB Variant Part A
- Figure 13: Schematic of the NCV7685LOWR1GEVB Part B
- Figure 14: Schematic of the NCV7685MIDR1GEVB Part A
- Figure 15: Schematic of the NCV7685MIDR1GEVB Part B
- Figure 16: Schematic of the NCV7685HIGH1GEVB Part A
- Figure 17: Schematic of the NCV7685HIGH1GEVB Part B
- Figure 18: Schematic of the NCV7685BCMR1GEVB Board
PCB Preview
- Figure 19: NCV7685LOWR1GEVB EVB PCB Top Side View
- Figure 20: NCV7685MIDR1GEVB EVB PCB Top Side View
- Figure 21: NCV7685HIGH1GEVB EVB PCB Top Side View
- Figure 22: NCV7685BCMR1GEVB EVB PCB Top Side View
References
- ON Semiconductor, NCV7685 Rev.2, October 2020
- ON Semiconductor, NCV8853: Automotive Grade Non−Synchronous Buck Controller Rev.5, October 2016
- ON Semiconductor, AND9764/D: NCV7685 I2C programming Guide, May 2020 Rev.2