LB1694N datasheet(6/8 Pages) SANYO

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Hall input circuit

The Hall input circuit is a differential amplifier with hysteresis (30 mV typ). The operating DC level must be within the

common-mode input voltage range (1.5 V to VCC – 1.8 V). An input level that is at least three times greater than the hysteresis

(from 120 to 160 mVp-p) is recommended to be independent of noise, etc. If the handling capability needs to be considered in

noise evaluation, etc., connect a capacitor (about 0.01 µF) between the Hall inputs IN

+ and IN–.

Protectors

2-1. Reduced voltage protector

If VCC drops below the prescribed voltage (VLVSD), the output transistor on the sink side turns off. This protector prevents

malfunction which may occur when VCC is reduced.

2-2. Thermal shutdown protector

If the junction temperature exceeds the prescribed temperature (TSD), the output transistor on the sink side turns off. This

protector prevents the IC from being damaged by heat. Thermal design must be such that no operation is performed in other

modes than abnormality.

FG output circuit

IN1, IN2, and IN3 Hall input signals are composited and wave shaped to be output. FG1 has the same frequency as for Hall input,

while FG2 3-fold as many.

Forward/reverse controller

No forward/reverse (F/R) switching is assumed to be performed during motor running period. If F/R switching is performed

during motor running period, through current flows to output and ASO needs to be considered. It is recommended that F/R

switching be performed when the VM power supply is off (in motor stop mode).

VCC and VM power supplies

If the supply voltage (VCC,VM) rise rate is fast when power is applied, through current flows to output and ASO needs to be

considered. The supply voltage rise rate must be such that

∆V

CC/∆t = 0.04 V/µs or less and ∆VM/∆t = 0.16 V/µs or less. The

desirable order of applying power is VCC on first and then VM on. The desirable order of turning off power supply is VM off first

and then VCC off after motor stop. If, after VM is turned off, VCC is turned off during motor’s inertial running, some types of

motors have a possibility that VM voltage rises, exceeding the withstand voltage.

Power supply stabilization capacitor

Great fluctuations in the VCC line may cause the reduced-voltage protector, etc. to malfunction. A capacitor (several µF) needs to

be connected to the VCC line (between VCC and GND) for stabilization. Since a large switching current flows in the VM line,

wiring inductance component, etc. fluctuates. Because there are also fluctuations in the GND line, a capacitor needs to be

connected to the VM line (between VM and GND) for stabilization thus preventing malfunction and keeping the withstand voltage

from being exceeded. Especially when the routing of wiring (VM,VCC, or GND) is long, be sure to connect capacitors with

adequate capacity for power line stabilization.

Current limiter

The current limiter turns off the sink side output transistor when the output current-set current value (limiter value) is reached. The

output current is limited by the limit value. The RF pin is used to detect the output current. The output current is detected as

voltage by connecting resistor Rf between RF pin and GND. When the RF pin voltage reaches 0.5 V (typ), the current limiter

operates so that the output current is limited to the 0.5/Rf-set limiter value.

LB1694N

No.5243-6/8

LB1694N Datasheet(PDF) 6 Page - Sanyo Semicon Device

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