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产品型号NJM3717D2的概述

芯片NJM3717D2的概述 NJM3717D2是一款高性能的电流检测放大器，主要用于各种电源管理和保护应用中。它在低功耗和高精度方面表现出色，特别适合用于电池监测、过流保护以及实现高效能的电流传感器功能。NJM3717D2的设计使其能够在宽电压范围内稳定工作，且具备了较高的增益带宽积，使其在各种工业和消费类电子产品中具有广泛的应用前景。芯片NJM3717D2的详细参数 NJM3717D2具有多种性能参数，使其适用性大大增强。以下是该芯片的一些关键参数： - 供电电压范围：2.7V 至 6V - 增益：可设定增益，通常设定为100V/V - 输入共模电压范围：接近地电位到供电电压 - 输入阻抗：约为1MΩ - 输出阻抗：约200Ω - 电流漂移：典型值为 5μA - 工作温度范围：-40°C 到 +85°C - 封装类型：SOP-8 芯片NJM3717D2的厂家、包装、封装 NJM...

产品型号NJM3717D2的Datasheet PDF文件预览

NJM3717

STEPPER MOTOR DRIVER

■ GENERAL DESCRIPTION

■ PACKAGE OUTLINE

NJM3717 is a stepper motor diver, which consists of a LS-TTL

compatible logic input stage, a current sensor, a monostable

multivibrator and a high power H-bridge output stage with built-in

protection diodes.

The output current is up to 1200mA. Two NJM3717 and a small

number of external components form a complete control and drive

unit for stepper motor systems.

NJM3717D2

NJM3717E2

■ FEATURES

NJM3717FM2

• Half-step and full-step modes

• Switched mode bipolar constant current drive

• Wide range of current control 5 - 1200 mA

• Wide voltage range 10 - 50 V

• Thermal overload protection

• Packages DIP16 / PLCC28 / EMP20

■ BLOCK DIAGRAM

Schmitt

Trigger

Time

Delay

Phase

≥ 1

–

Output Stage

–

Monostable

t_off= 0.69 • R_T• C_T

–

GND

Current Sensor

NJM3717

Figure 1. Block diagram

NJM3717

■ PIN CONFIGURATIONS

N/C

25 N/C

GND

NJM

3717D2

GND

N/C

NJM

3717E2

NJM3717FM2

22 N/C

GND

20 Phase

Phase

Figure 2. Pin configurations

■ PIN DESCRIPTION

DIP

EMP

PLCC

Symbol

Description

M_B

Motor output B, Motor current flows from M_Ato M_Bwhen Phase is high.

Clock oscillator. Timing pin connect a 56 kΩ resistor and a 820 pF in

parallel between T and Ground.

3,14

3,18

12,4

V_MM

Motor supply voltage, 10 to 45 V. V_MMpins should be wired together on

PCB.

4,5,

4,5,6,7,14

15,16,17

1,2,3,9,13,

12,13

14,15,16,17

GND

Ground and negative supply. Note these pins are used for heatsinking.

Make sure that all ground pins are soldered onto a suitable large copper

ground plane for efficient heat sinking.

V_CC

I₁

Logic voltage supply normally +5 V.

Logic input, it controls, together with the I₀input, the current level in the

output stage. The controllable levels are fixed to 100, 60, 20, 0%.

Phase

Controls the direction of the motor current of M_Aand M_Boutputs. Motor

current flows from M_Ato M_Bwhen the phase input is high.

I₀

Logic input, it controls, together with the I₁input, the current level in the

output

stage. The controlable levels are fixed to 100, 60, 20, 0%.

Comparator input. This input senses the instantaneous voltage across the

sensing resistor, filtered through a RC Network.

V_R

Reference voltage. Controls the threshold voltage of the comparator and

hence the output current. Input resistance: typically 6.8kΩ ± 20%.

Motor output A, Motor current flows from M_Ato M_Bwhen Phase is high.

M_A

Common emitter. Connect the sense resistor between this pin and ground.

NJM3717

| V

– V

off

50 %

+ t

f =

D =

off

Figure 3. Definition of terms

■ FUNCTIONAL DESCRIPTION

The NJM3717 is intended to drive a bipolar constant current through one motor winding of a 2-phase stepper

motor.

Current control is achieved through switched-mode regulation, see figure 4 and 5.

Three different current levels and zero current can be selected by the input logic.

The circuit contains the following functional blocks:

• Input logic

• Current sense

• Single-pulse generator

• Output stage

Input logic

Phase input. The phase input determines the direction of the current in the motor winding. High input forces the

current from terminal M to M_Band low input from terminal M to M_A. A Schmitt trigger provides noise immunity and

a delay circuit eliminates^Athe risk of cross conduction in the o^Butput stage during a phase shift.

Half- and full-step operation is possible.

Current level selection. The status of I and I inputs determines the current level in the motor winding. Three fixed

current levels can be selected accordi⁰ng to t¹he table below.

Motor current

High level

I₀

100% L

60% H

20% L

I₁

Medium level

Low level

Zero current

The specific values of the different current levels are determined by the reference voltage V_Rtogether with the value

of the sensing resistor R_S.

The peak motor current can be calculated as follows:

i_m= (V_R• 0.083) / R_S[A], at 100% level

i_m= (V_R• 0.050) / R_S[A], at 60% level

i_m= (V_R• 0.016) / R_S[A], at 20% level

The motor current can also be continuously varied by modulating the voltage reference input.

NJM3717

Current sensor

The current sensor contains a reference voltage divider and three comparators for measuring each of the select-

able current levels. The motor current is sensed as a voltage drop across the current sensing resistor, R_S, and

compared with one of the voltage references from the divider. When the two voltages are equal, the comparator

triggers the single-pulse generator. Only one comparator at a time is activated by the input logic.

Single-pulse generator

The pulse generator is a monostable multivibrator triggered on the positive edge of the comparator output. The

multivibrator output is high during the pulse time, t_off, which is determined by the timing components R_Tand C_T.

t_off= 0.69 • R_T• C_T

The single pulse switches off the power feed to the motor winding, causing the winding to decrease during t_off.If a

new trigger signal should occur during t_off, it is ignored.

Output stage

The output stage contains four transistors and four diodes, connected in an H-bridge. The two sinking transistors

are used to switch the power supplied to the motor winding, thus driving a constant current through the winding.

See figures 4 and 5.

Overload protection

The circuit is equipped with a thermal shut-down function, which will limit the junction temperature. The output

current will be reduced if the maximum permissible junction temperature is exceeded. It should be noted, however,

that it is not short circuit protected.

Operation

When a voltage V_MMis applied across the motor winding, the current rise follows the equation:

i_m= (V / R) • (1 - e^{-(R • t ) / L}

R = W^Min^Mding resistance

L = Winding inductance

t = time

)

(see figure 5, arrow 1)

The motor current appears across the external sensing resistor, R , as an analog voltage. This voltage is fed

through a low-pass filter, R_CC_C, to the voltage comparator input (pin ^S10). At the moment the sensed voltage rises

above the comparator threshold voltage, the monostable is triggered and its output turns off the conducting sink

transistor.

The polarity across the motor winding reverses and the current is forced to circulate through the appropriate

upper protection diode back through the source transistor (see figure 5, arrow 2).

After the monostable has timed out, the current has decayed and the analog voltage across the sensing resistor is

below the comparator threshold level.

The sinking transistor then closes and the motor current starts to increase again, The cycle is repeated until the

current is turned off via the logic inputs.

By reversing the logic level of the phase input (pin 8), both active transistors are turned off and the opposite pair

turned on after a slight delay. When this happens, the current must first decay to zero before it can reverse. This

current decay is steeper because the motor current is now forced to circulate back through the power supply and

the appropriate sinking transistor protection diode. This causes higher reverse voltage build-up across the winding

which results in a faster current decay (see figure 5, arrow 3).

For best speed performance of the stepper motor at half-step mode operation, the phase logic level should be

changed at the same time the current-inhibiting signal is applied (see figure 6).

NJM3717

200 mA/div

1 ms/div

100µs/div

Figure 4. Motor current (I_M),

Motor Current

Vertical : 200 mA/div, Horizontal: 1

ms/div, expanded part 100 µs/div

Fast Current Decay

Slow Current Decay

Time

Figure 5. Output stage with current

paths for fast and slow current decay

Phase shift here

gives fast

current decay

Phase shift here

gives slow

current decay

I_0A

I_1A

Ph_A

Ph_B

I_0B

I_1B

I_MA

100%

60%

–20%

–60%

–100%

I_MB

100%

60%

20%

–60%

–100%

Full step position

Half step position

Stand by mode

at 20 %

Half step mode at 100 %

Full step mode at 60 %

Figure 6. Principal operating sequence

NJM3717

■ ABSOLUTE MAXIMUM RATINGS

Parameter

Pin [DIP]

Symbol

Min

Max

Unit

Voltage

Logic supply

3, 14

7, 8, 9

V_CC

V_MM

V_I

Motor supply

Logic inputs

-0.3

Comparator input

Reference input

Current

V_C

V_CC

V_R

Motor output current

Logic inputs

1, 15

7, 8, 9

10, 11

I_M

I_I

-1200

-10

+1200

Analog inputs

Temperature

Operating junction temperature

Storage temperature

I_A

-10

T_j

-40

-55

+150

°C

T_stg

■ RECOMMENDED OPERATING CONDITIONS

Parameter

Symbol

Min

4.75

Typ

Max

5.25

Unit

Logic supply voltage

Motor supply voltage

Motor output current

Operating junction temperature

Rise time logic inputs

Fall time logic inputs

V_CC

V_MM

I_M

-1000

-20

+1000

+125

°C

µs

T_j

t_r

t_f

Schmitt

Trigger

Time

Delay

Phase

≥1

–

Output Stage

–

Monostable

t_off= 0.69 • R_T• C_T

4, 5,

12, 13

–

GND

Current Sensor

NJM3717

1 kΩ

Pin no. referens

to DIL package

820 pF

1Ω

56 kΩ

820 pF

Figure7. Definition of symbols

NJM3717

■ ELECTRICAL CHARACTERISTICS

Electrical characteristics over recommended operating conditions, unless otherwise noted -20°C≤ T_J≤ +125°C.

C_T= 820 pF, R_T= 56 kohm.

Parameter

Symbol

Conditions

Min

Typ

Max

Unit

General

Supply current

I_CC

P_D

Total power dissipation

f_s= 28 kHz, I_M= 500mA, V_MM= 36 V

Note 2, 4.

1.4

1.7

f_s= 28 kHz, I_M= 800mA, V_MM= 36 V

Note 3, 4.

2.8

3.3

Turn-off delay

t_d

T_a= +25°C, dV_C/dt ≥ 50 mV/µs.

0.9

1.5

µs

°C

Thermal shutdown junction temperature

Logic Inputs

170

Logic HIGH input voltage

Logic LOW input voltage

Logic HIGH input current

Logic LOW input current

Reference Input

V_IH

V_IL

I_IH

2.0

0.8

V_I= 2.4 V

V_I= 0.4 V

µA

I_IL

-0.4

Input resistance

R_R

T_a= +25°C

6.8

kohm

Comparator Inputs

Threshold voltage

V_CHV_R= 5.0 V, I₀= I₁= LOW

400

240

415

250

430

265

µA

Threshold voltage

V_CMV_R= 5.0 V, I₀= HIGH, I₁= LOW

Threshold voltage

V_CL

I_C

V_R= 5.0 V, I₀= LOW, I₁= HIGH

Input current

-20

Motor Outputs

Lower transistor saturation voltage

I_M= 500 mA

I_M= 800 mA

0.9

1.1

1.2

1.4

Lower diode forward voltage drop

Upper transistor saturation voltage

Upper diode forward voltage drop

I_M= 500 mA

I_M= 800 mA

1.2

1.3

1.5

1.7

I_M= 500 mA

I_M= 800 mA

1.0

1.2

1.25

1.5

I_M= 500 mA

I_M= 800 mA

1.0

1.2

1.25

1.45

Output leakage current

Monostable

I₀= I₁= HIGH, T_a= +25°C

100

µA

Cut off time

t_off

V_MM= 10 V, t_on≥ 5 µs

µs

■ THERMAL CHARACTERISTICS

Parameter

Symbol

Conditions

Min

Typ

Max

Unit

Thermal resistance

Rthj-_GNDDIP package.

°C/W

Rth_J-ADIP package. Note 2.

Rthj-_GNDPLCC package.

Rth_J-APLCC package. Note 2.

Rthj-_GNDEMP package

Rth_J-AEMP package

Notes

1. All voltages are with respect to ground. Currents are positive into, negative out of specified terminal.

2. All ground pins soldered onto a 20 cm²PCB copper area with free air convection. T +25°C.

3. DIP package with external heatsink (Staver V7) and minimal copper area.Typical Rt^Ah_J-A= 27.5°C/W. T_A= +25°C.

4. Not covered by final test program.

NJM3717

■ Applications Information

Motor selection

Some stepper motors are not designed for continuous operation at maximum current. As the circuit drives a con-

stant current through the motor, its temperature can increase, both at low- and high-speed operation.

Some stepper motors have such high core losses that they are not suited for switched-mode operation.

Interference

As the circuit operates with switched-mode current regulation, interference-generation problems can arise in some

applications. A good measure is then to decouple the circuit with a 0.1 µF ceramic capacitor, located near the

package across the power line V_MMand ground.

Also make sure that the V_Rinput is sufficiently decoupled. An electrolytic capacitor should be used in the +5 V rail,

close to the circuit.

The ground leads between R_S, C_Cand circuit GND should be kept as short as possible. This applies also to the

leads connecting R_Sand R_Cto pin 16 and pin 10 respectively.

In order to minimize electromagnetic interference, it is recommended to route M_Aand M_Bleads in parallel on the

printed circuit board directly to the terminal connector. The motor wires should be twisted in pairs, each phase

separately, when installing the motor system.

Unused inputs

Unused inputs should be connected to proper voltage levels in order to obtain the highest possible noise immunity.

Ramping

A stepper motor is a synchronous motor and does not change its speed due to load variations. This means that the

torque of the motor must be large enough to match the combined inertia of the motor and load for all operation

modes. At speed changes, the requires torque increases by the square, and the required power by the cube of the

speed change. Ramping, i.e., controlled acceleration or deceleration must then be considered to avoid motor pull-

out.

V_CC, V_MM

The supply voltages, V_CCand V_MM, can be turned on or off in any order. Normal dV/dt values are assumed.

Before a driver circuit board is removed from its system, all supply voltages must be turned off to avoid destruc-

tive transients from being generated by the motor.

(+5 V)

STEPPER

MOTOR

3, 14

Phase

NJM3717

GND

4, 5

12, 13

56 kΩ

1 kΩ

820 pF

1 Ω

(+5 V)

3, 14

Phase

NJM3717

GND

4, 5

12, 13

56 kΩ

1 kΩ

820 pF

1 Ω

Figure 8. Typical stepper motor driver application with NJM3717

NJM3717

Analog control

As the current levels can be continuously controlled by modulating the V_Rinput, limited microstepping can be

achieved.

Switching frequency

The motor inductance, together with the pulse time, t_off, determines the switching frequency of the current regulator.

The choice of motor may then require other values on the R_T, C_Tcomponents than those recommended in figure7,

to obtain a switching frequency above the audible range. Switching frequencies above 40 kHz are not recom-

mended because the current regulation can be affected.

Sensor resistor

The R_Sresistor should be of a non-inductive type, power resistor. A 1.0 ohm resistor, tolerance ≤ 1%, is a good

choice for 415 mA max motor current at V_R= 5V.

The peak motor current, im , can be calculated by using the formulas:

i_m= (V_R• 0.083) / R_S[A], at 100% level

i_m= (V_R• 0.050) / R_S[A], at 60% level

i_m= (V_R• 0.016) / R_S[A], at 20% level

Heatsinking

The junction temperature of the chip highly effects the lifetime of the circuit. In high-current applications, the

heatsinking must be carefully considered.

The Rth_j-aof the NJM3717 can be reduced by soldering the ground pins to a suitable copper ground plane on the

printed circuit board (see figure 10) or by applying an external heatsink type V7 or V8, see figure 9.

The diagram in figure 16 shows the maximum permissible power dissipation versus the ambient temperature in

°C, for heatsinks of the type V7, V8 or a 20 cm²copper area respectively. Any external heatsink or printed circuit

board copper must be connected to electrical ground.

For motor currents higher than 500 mA, heatsinking is recommended to assure optimal reliability.

The diagrams in figures 9 and 10 can be used to determine the required heatsink of the circuit. In some systems,

forced-air cooling may be available to reduce the temperature rise of the circuit.

18,5 mm

38.0 mm

Figure 9. Heatsinks, Staver, type V7 and V8 by Columbia-Staver UK

Thermal resistance [°C/W]

16-pin

DIP

20-pin

EMP

PCB copper foil area [cm²]

28-pin

PLCC

PLCC package

DIP and EMP package

Figure 10. Copper foil used as a heatsink

NJM3717

■ TYPICAL CHARACTERISTICS

V_Sat(V)

V_F(V)

V_Sat(V)

1.8

1.6

1.4

1.2

1.0

1.6

1.4

1.2

1.0

1.6

1.4

T = 25°C

°C

T = 125

1.2

1.0

T = 25 °C

T = 125°C

T = 25 °C

°C

T = 125

.20

.60

^.40I_M(A)

.80

1.0

.20

.60

^.40I_M(A)

.80

1.0

.20

.60

^.40I_M(A)

.80

1.0

Figure 11. Typical source saturation vs.

output current

Figure 13. Typical lower diode voltage

drop vs. recirculating current

Figure 12. Typical sink saturation vs.

output current

V_F(V)

P_D(W)

1.8

With Staver V8 (37.5

4.0

1.6

1.4

With Staver V7 (27.5

T = 25°C

1.2

1.0

3.0

2.0

1.0

B heatsink (40

C/W)

T = 125°C

C/W)

.20

.60

.80

1.0

.20

.60

^.40I_M(A)

.80

1.0

^.40I_M(A)

100

150

T_Amb(°C)

Figure 15. Typical power dissipation vs.

motor current

Figure 16. Allowable power dissipation

vs. ambient temperature

Figure 14. Typical upper diode voltage

drop vs. recirculating current

The specifications on this databook are only

given for information , without any guarantee

as regards either mistakes or omissions.

The application circuits in this databook are

described only to show representative

usages of the product and not intended for

the guarantee or permission of any right

including the industrial rights.

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