ON Semiconductor NCL30105G1EVB VCSEL Driver with Buck PWM Controller Evaluation Board User Manual

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EVAL BOARD USER’S MANUAL
VCSEL Driver with Buck PWM Controller Evaluation Board
User’s Manual
NCL30105G1EVB

Overview

This manual covers the specification, theory of operation, testing, and construction of the NCL30105G1EVB evaluation board. This evaluation board uses NCL30105 as a high pulse current low duty cycle VCSEL driver. The expected duty cycle is less than 5% in typical applications. The NCL30105 is an inverted buck converter design with constant off-time control.

Features

The key features of this evaluation board include:

• High Peak Current
• Small Size
• Fast Rise/Fall Time
• PWM Control

SPECIFICATIONS

THEORY OF OPERATION

Overview
The NCL30105G1EVB drives a low voltage high current VCSEL for camera illumination for the automotive market.

Current Control
The NCL30105 is a peak current mode control with constant off time. Peak current control provides accurate current regulation. The value of R7 sets the peak current as follows:

The soft-start pin controls the peak current at turn-on. A capacitor on this pin is charged up by a 20 or internal current source. For PWM operation this capacitor is very small to allow for fast rise times. Analog dimming can be done by programming the voltage on the soft-start pin. The connection for this option is not brought out on this demo board although this control method is still available. The off-time is held constant in operation. R5 programs the off time. Constant off-time control eliminates sub-harmonic oscillation in buck converters where the duty cycle exceeds 50%. The on-time is determined by the input voltage, the output voltage, and the inductor value.

Consequently, the switching frequency will vary over the line and load conditions even though the off time is constant. The NCL30105 has a maximum on-time ~34us which is set internally.
Vcc
Q1 is an emitter follower that limits Vcc to ~14 V. The NCL30105 has an upper Vcc limit of 22 V. Some automotive applications exceed the 22 V limit, especially in the case of
load dump.
Current Sense
The current sense pin has a Leading Edge Blanking (LEB) function to avoid false triggering of the current sense comparator. The LEB is ~500 ns.
Dimming
The demo board is set up for PWM dimming through J3 (SMA). A 0−5 V square wave signal will provide PWM dimming. In the absence of a signal to J3, the output defaults
to off.
The output current (green trace) follows the PWM input signal (yellow trace). The output filter affects the rise and fall times.

The rise and fall times are affected by the output filter values. Raising the FSW will reduce the size requirement for the output capacitor which reduces rise and fall times.
Reducing the off time will increase the switching frequency and reduce the current ripple for a given output inductor.

SCHEMATIC

BILL OF MATERIAL

Qty

| Reference| Part| Distributor| Dist. PIN| Manufacturer| Mfr_PN| Insert|

Safety
Controlled

---|---|---|---|---|---|---|---|---
5| C1, C2,
C3, C4,
C6| 4.7 pF 25 V| Digikey| 1276-3178-1-ND| Samsung| CL31B475KAHN
NEW| Yes| No
2| C5, C7| 220 pF| Digikey| 311-1416-1-ND| Yageo| CC0402JRNP09
BN221| Yes| No
1| D1| FSV530AF| ON
Semiconductor| FSV530AFCT-ND| ON
Semiconductor| FSV530AF| Yes| No
1| D2| SZMM3Z15V
T1G| ON
Semiconductor| SZMM3Z15VT1GOS
CT-ND| ON
Semiconductor| SZMM3Z15VT1G| Yes| No
1| J1| CONN JACK
PWR| Digikey| 732-5929-1-ND| Wurth| 694106106102| Yes| No
1| J2| OSTTA024163| Digikey| ED2580-ND| On Shore| OSTTA024163| Yes| No
1| J3| SMA| Digikey| WM5525-ND| Molex| 731000114| Yes| No
1| L1| 4.7 RH| Digikey| 587-1624-1-ND| Taiyo Yuden| CBC3225T4R7MR| Yes| No
1| L2| 15 pH| Digikey| 732-1242-1-ND| Wurth| 7447709150| Yes| No
1| Q1| MMBT3904W
T1G| ON
Semiconductor| MMBT3904WT1G| ON
Semiconductor| MMBT3904VVT1G| Yes| No
1| Q2| NVMFS5C46
8NT1G| ON
Semiconductor| NVMFS5C468NT1G
OSCT-ND| ON
Semiconductor| NVMFS5C468NT
1G| Yes| No
1| R1| 10k| Digikey| 311-10.0KLRCT-ND| Yago| RC0402FR-0710
KL| Yes| No
2| R2, R3| 49.9| Digikey| 311-49.9LRCT-ND| Yago| RC0402FR-0749
R9L| Yes| No
2| R4, R6| 100| Digikey| 311-100LRCT-ND| Yago| RC0402FR-0710
ORL| Yes| No
1| R5| 30k| Digikey| 311-30.0KLRCT-ND| Yago| RC0402FR-0730
KL| Yes| No
1| R7| 220m| Digikey| 408-1608-1-ND| Susumu| KRL2012E-M-R2
20-F-T5| Yes| No
1| U1| NCL30105DR
2G| ON
Semiconductor| NCL30105DR2GOS
CT-ND| ON
Semiconductor| NCL30105DR2G| Yes| No

TEST PROCEDURE

1. Require Equipment
   a. DC Power Supply 12 V @ 2 A
   b. Function Generator
   c. LED Load similar to Luminus
   CBT−90−B−L11−J101 (observe the correct polarity)

2. Connector the LED Load to J2

3. Apply 12 V to J1 (2.1 x 5.5 Power Connector)

4. Connect a function generator and set it as follows:
   a. Frequency – 100 Hz
   b. Duty Cycle – 5%
   c. Vin – 0−5 V (into a 50 Ω load)

5. Observe that the output current transitions from 0 to ~4 A in sync with the function generator output.

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The evaluation board/kit (research and development board/kit) (hereinafter the “board”) is not a finished product and is as such, not available for sale to consumers. The board is only intended for research, development, demonstration, and evaluation purposes and should as such only be used in laboratory/development areas by persons with engineering/technical training and familiar with the risks associated with handling electrical/mechanical components, systems, and subsystems. This person assumes full responsibility/liability for proper and safe handling.

Any other use, resale, or redistribution for any other purpose is strictly prohibited. The board is delivered “AS IS” and without warranty of any kind including, but not limited to, that the board is production−worthy, that the functions contained in the board will l meet your requirements, or that the operation of the board will be uninterrupted or error-free. ON Semiconductor expressly disclaims all warranties, express, implied, or otherwise, including without limitation, warranties of fitness for a particular purpose and non−infringement of intellectual property rights.

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You are responsible for determining whether the board will be suitable for your intended use or application or will achieve your intended results. Prior to using or distributing any systems that have been evaluated, designed, or tested using the board, you agree to test and validate your design to confirm the functionality of your application. Any technical, applications or design information or advice, quality characterization, reliability data, or other services provided by ON Semiconductor shall not constitute any representation or warranty by ON Semiconductor, and no additional obligations or liabilities shall arise from ON Semiconductor having provided such information or services.

The boards are not designed, intended, or authorized for use in life support systems, or any FDA Class 3 medical devices or medical devices with a similar or equivalent classification in a foreign jurisdiction, or any devices intended for implantation in the human body. Should you purchase or use the board for any such unintended or unauthorized application, you shall indemnify and hold ON Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that ON Semiconductor was negligent regarding the design or manufacture of the board.

This evaluation board/kit does not fall within the scope of the European Union directives regarding electromagnetic compatibility, restricted substances (RoHS), recycling (WEEE), FCC, CE, or UL, and may not meet the technical requirements of these or other related directives.
FCC WARNING – This evaluation board/kit is intended for use for engineering development, demonstration, or evaluation purposes only and is not considered by ON Semiconductor to be a finished end-product fit for general consumer use. It may generate, use, or radiate radio frequency energy and has not been tested for compliance with the limits of computing devices pursuant to part 15 of FCC rules, which are designed to provide reasonable protection against radio frequency interference. Operation of this equipment may cause interference with radio communications, in which case the user shall be responsible, at its expense, to take whatever measures may be required to correct this interference.
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