The LTC4015 synchronous step-down battery charger controller from Linear Technology offers charge current of up to 20 A, multiple-chemistry operation, and onboard digital telemetry. The controller transfers power from a variety of input sources, such as wall adapters and solar panels, to a Li-Ion polymer, LiFePO4, or lead-acid battery stack with system load up to 35 V.
Operating over an input voltage range of 4.5 V to 35 V, the LTC4015 provides ±5% charge-current regulation up to 20 A and ±0.5% charge-voltage regulation. While a host microcontroller is required to access the most advanced features of the LTC4015, the use of an I2C port is optional.
When working with discrete JFETs, designers may need to accommodate a large variation in device parameters for a given transistor type. A square-law equation is usually used as an approximate model for the drain-current characteristic of the JFET: ID=β(VGS−VP)2, where ID is the drain current, VGS is the gate-to-source voltage, β is the transconductance parameter, and VP is the gate pinch-off voltage. With this approximation, the following equation yields the zero-bias drain current at a gate-to-source voltage of 0V: IDSS=βVP 2, where IDSS is the zero-bias drain current.
Simple circuit lets you characterize JFETs – [Link]
Tiny Board has been designed around LV8772 IC from On-Semi. This driver is capable of micro-step drive and supports 4W 1-2 phase excitation. It has Low on Resistance with motor current selectable in four steps. The board is equipped with unusual condition warning LED and input Pulse Monitor LED. It is most suitable for the drive of a stepping motor for OA, amusements, hobby CNC, 3D printers, automatic machines, linear guides, motion control systems, XY gantry, Camera focus and zoom controller, Mini camera Pan Tilt Head.
2.5A BIPOLAR STEPPER MOTOR DRIVER LV8772E – [Link]
I/O Expander Board offers a convenient way to interface upto 16 I/O pins in your project using SPI/I2C bus. This kit uses the famous MCP23S17 IO chip from Microhip.
Specifications
Supply sourced through the interfacing Box Header connector
The kit has 2 separate Box Header type connector for the 16 pins of I/O port and 1 Box Header for interfacing of the PCB with the host controlling circuit
Jumper selectable address option is also available for this kit
Tiny Board has been designed around LV8772 IC from On-Semi. This driver is capable of micro-step drive and supports 4W 1-2 phase excitation. It has Low on Resistance with motor current selectable in four steps. The board is equipped with unusual condition warning LED and input Pulse Monitor LED. It is most suitable for the drive of a stepping motor for OA, amusements, hobby CNC, 3D printers, automatic machines, linear guides, motion control systems, XY gantry, Camera focus and zoom controller, Mini camera Pan Tilt Head.
Specifications
Power Supply input 9V to 30V (Max 32V)
Output Current 2.5Amps
Very low noise and smooth operations
Very low noise in slow speed
Low on resistance (Total of upper and lower: 0.55ohms)
Micro-Step mode can be set to Full-Step, 1/2 Step,1/4,1/16 Steps
Motor Current selectable in four steps
Output short circuit protection circuit incorporated (IC)
Current Setting via onboard Preset (Potentiometer)
Attenuation ATT1 and ATT2 by Jumpers
Two Jumpers for Micro-Step settings
On-Board Fault Warning LED
On-Board Pulse Input indication LED
Applications
Slot Machine
Vending Machine
Cash Machine
PPC (Plain Paper Copier)
LBP (Laser Beam Printer)
Scanner
CNC
3D Printers
Textile
Camera Pan Tilt Head
Camera Focus and Zoom Controller
Chip Enable Functions (Default this pin set to high for normal operation)
ST Pin High Operation Mode, Low Disable the drive
This IC is switched between standby and operating mode by setting the ST pin, In standby mode, the IC is set to power-save mode and all logic is reset. In addition, the internal regulator circuit and charge pump circuit do not operate in standby mode.
Position detection monitoring function (LED MO, D2)
When the excitation position is in the initial position, the Monitor output LED MO D2 placed in the ON State
Setting constant-current control reference current (PR1 Potentiometer)
Potentiometer PR1 is to set the Current
RESET Function (Default this pin set to normal operation using pull down resistor R10)
Reset Pin Low = Normal Operation, Reset Pin High = Reset State
When The RST pin is set to High, the excitation position of the output is forcibly set to the initial state, and the Moni -D2 LED is in ON state, When RST is set to low , the excitation position is advanced by the next STEP input
Output Short Circuit
Output Short-Circuit protection type of IC is latch type to turn off when the output current exceeds the detection current and the state is maintained. The output short-circuit protection circuit is activated in and event of short-circuit in the output pin. When the short-circuit state continues for a period of time set by the internal timer (approximately 4uS), the output in which short-circuit was first detected are switched to the standby mode, And if the short-circuit state is still detected, all the outputs of the channel are switched to the standby mode, and the state is held, this state is released by setting ST to low.
EMO Unusual condition warning output pin (Fault LED D1)
This board is provided with EMO (Fault LED) which notifies the CPU of an unusual condition if the protection circuit operates by detecting an unusual condition of the IC, When an unusual condition is detected , the Fault LED D1 is placed in the ON (EMO=Low)
Chopping Frequency
F-Chop 10uA/180PF/).5VX2=55Khz
Connections
CN1: Power Supply In
CN2: Bipolar Stepper Motor Connections
CN6: Control Signal Inputs ( All inputs are TTL Level)
Pin1 5V : DC Aux ( Output)
Pin 2 ENB : Enable ( Default set to Enable , Required low input (Pull Down) to disable)
Pin3 CK : Clock input to excite the motor ( Pulse Inputs)
Pin 4 : GND Ground Signal
Pin5 : RS : Reset input
PR1: Onboard Preset (Potentiometer) to set the Current
A1,A2: To Set the Motor Holding Current (A1=ATT1, A2=ATT2)
MICRO-STEP SETTINGS
SR
M1
M2
Micro-Step RESOLUTION
1
LOW
LOW
FULL STEP
2
HIGH
LOW
HALF STEP
3
LOW
HIGH
QUARTER STEP
4
HIGH
HIGH
1/16 STEP
JUMPER CLOSED=LOW I JUMPER OPEN= HIGH
Current Setting Reference Voltage Attenuation Ratio (A1 & A2 Closed= Low, Open=High)
ATT1-A1 Low I ATT2-A2 Low = 100%
ATT1-A1 High I ATT2-A2 Low = 80%
ATT1-A1 Low I ATT2-A2 High = 50%
ATT1-A1 High I ATT2-A2 High = 20%
The formula used to calculate the output current when using the function for attenuating the VREF input voltage is giving bellow
I out+(VREF/%)X(Attenuation Ratio)/RF resistance
Example: At VREF of 1.0V, a reference voltage setting of 100% (ATT1-A1=Low ATT2-A2=Low) and an RF resistance of 0.5 Ohms, the output current is set as shown bellow,
I-Out=1.0VX5X100%/0.22Ohms=0.91A
If, in this state (ATT1-A1=High, ATT2-A2=High), I-Out will be as follows:
I-Out =0.91AX50%=455Ma
In this way, the output current is attenuated when the motor holding current is supplied so that power can be conserved.
I/O Expander Board offers a convenient way to interface upto 16 I/O pins in your project using SPI/I2C bus. This kit uses the famous MCP23S17 IO chip from Microhip.
Specifications
Supply sourced through the interfacing Box Header connector
The kit has 2 separate Box Header type connector for the 16 pins of I/O port and 1 Box Header for interfacing of the PCB with the host controlling circuit
Jumper selectable address option is also available for this kit
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