AN1041

```Application Note 1041
The Design Guide for AM4962
Prepared by Zhihong Zhang
Design Engineering Dept.
1. Introduction
3.3 Measure Parameter
Solder D1, C1, C2, C3 and hall sensor onto the PCB
(R1, R2, R3, R4, R5, R6 open); Measure the fan
rotating speed vs. input duty, and draw a curve figure
accordingly (Step=5%), as Figure 4.
The AM4962 is a full wave driver IC with direct
PWM control function, which features as below:
• Motor Speed Directly Controlled by PWM Pulse
• Built-in Triangle Wave Circuit without Extra
Oscillation Capacitors
• Built-in Hall Bias Circuit
• Built-in Minimal Speed Setup Circuit
• Rotation Speed Indication (FG)
• Rotation or Lock State Indication (RD)
• Built-in Thermal Shutdown Circuit
• Lock Protection and Auto-restart
• Output Current Limit
Adjust the maximum speed vs. input duty to
approximately match the target specification via R3
and R4; Measure the fan rotating speed vs. input
duty, as shown in Table 3. And draw a curve figure
accordingly (Step=5%), as Figure 5.
Adjust Slope K of the fan rotating speed vs. input
duty to approximately match the target specification
via R5 and R6; Measure the fan rotating speed vs.
input duty, as shown in Table 4. And draw a curve
figure accordingly, as shown in Figure 6.
* Slope K is the slope of output PWM duty vs. input
PWM duty
This application note involves the general description,
recommended application steps and typical
application examples, which may be helpful to
designers in product development process.
Adjust the minimum speed vs. input duty to
approximately match the target specification via R2
(R1=15kΩ). Measure the fan rotating speed and the
input duty, as shown in Table 5. And draw a curve
figure accordingly, as shown in Figure 7.
2. General Description
The AM4962 is capable of speed control by PWM
pulse. It can be used in applications such as CPU
cooler fan in PC and brushless DC motor driver.
Note 1:
1) Mutual affections may occur when implementing
3.3 and 3.4. So, repeated adjustments may be needed.
2) About how R1, R2, R3, R4, R5 affect the
maximum speed, slope K and minimum speed, please
refer to the AM4962 Data Sheet (Page 12 to 13) for
details.
The AM4962 is available in HTSSOP-14 and
SSOP-16 packages.
3. Recommended Application Steps
3.1 Set Up Specification
Create a specification for the fan rotating speed vs.
input duty (Table 1.), and draw a curve figure
accordingly (Figure 1.).
3.2 Create PCB Drawing
Make a PCB drawing in accordance with the
recommended application circuit, as shown in
Figure 2. The soldering pad area contacted with the
power ground pin should be as large as possible to
ensure good heat dissipation ability. D2 and D3 are
recommended to be used when the current in coil L1
is higher than 300mA. A typical PCB application
example is shown in Figure 3.
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
1
Application Note 1041
Input
Duty
(%)
Lower
Limit
(RPM)
Target
(RPM)
Upper
Limit
(RPM)
Input
Duty
(%)
Lower
Limit
(RPM)
Target
(RPM)
Upper
Limit
(RPM)
Rotating
Speed
(RPM)
0
730
1110
1479
0
730
1110
1479
840
5
730
1110
1479
5
730
1110
1479
861
10
730
1110
1479
10
730
1110
1479
898
15
730
1110
1479
15
730
1110
1479
979
20
730
1110
1479
20
730
1110
1479
1060
25
730
1110
1479
25
730
1110
1479
1180
30
730
1110
1479
30
730
1110
1479
1300
35
929
1306
1673
35
929
1306
1673
1445
40
1128
1505
1867
40
1128
1505
1867
1590
45
1372
1701
2063
45
1372
1701
2063
1745
50
1525
1896
2255
50
1525
1896
2255
1900
55
1724
2092
2451
55
1724
2092
2451
2035
60
1922
2287
2642
60
1922
2287
2642
2170
65
2121
2483
2838
65
2121
2483
2838
2325
70
2319
2678
3030
70
2319
2678
3030
2480
75
2518
2874
3224
75
2518
2874
3224
2650
80
2717
3069
3418
80
2717
3069
3418
2820
85
2916
3265
3612
85
2916
3265
3612
2995
90
3114
3460
3806
90
3114
3460
3806
3179
95
3114
3460
3806
95
3114
3460
3806
3350
100
3114
3460
3806
100
3114
3460
3806
3500
Table 1. Specification for Rotating Speed
Dec. 2009
Table 2. Test Data
(R1, R2, R3, R4, R5, R6 open)
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
2
Application Note 1041
Input
Duty
(%)
Lower
Limit
(RPM)
Target
(RPM)
Upper
Limit
(RPM)
Rotating
Speed
(RPM)
Input
Duty
(%)
Lower
Limit
(RPM)
Target
(RPM)
Upper
Limit
(RPM)
Rotating
Speed
(RPM)
0
730
1110
1479
1453
0
730
1110
1479
850
5
730
1110
1479
1483
5
730
1110
1479
871
10
730
1110
1479
1524
10
730
1110
1479
908
15
730
1110
1479
1523
15
730
1110
1479
994
20
730
1110
1479
1552
20
730
1110
1479
1070
25
730
1110
1479
1616
25
730
1110
1479
1180
30
730
1110
1479
1695
30
730
1110
1479
1272
35
929
1306
1673
1823
35
929
1306
1673
1406
40
1128
1505
1867
1965
40
1128
1505
1867
1572
45
1372
1701
2063
2120
45
1372
1701
2063
1736
50
1525
1896
2255
2280
50
1525
1896
2255
1952
55
1724
2092
2451
2473
55
1724
2092
2451
2146
60
1922
2287
2642
2655
60
1922
2287
2642
2328
65
2121
2483
2838
2820
65
2121
2483
2838
2522
70
2319
2678
3030
3005
70
2319
2678
3030
2707
75
2518
2874
3224
3169
75
2518
2874
3224
2864
80
2717
3069
3418
3320
80
2717
3069
3418
3120
85
2916
3265
3612
3364
85
2916
3265
3612
3264
90
3114
3460
3806
3380
90
3114
3460
3806
3380
95
3114
3460
3806
3416
95
3114
3460
3806
3416
100
3114
3460
3806
3428
100
3114
3460
3806
3428
Table 3. Test Data　(R1, R2, R3, R5, R6 open, R4=200kΩ)
Dec. 2009
Table 4. Test Data　(R1, R2, R3, R6 open, R4=R5=200kΩ)
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
3
Application Note 1041
Input
Duty
(%)
Lower
Limit
(RPM)
Target
(RPM)
Upper
Limit
(RPM)
Rotating
Speed
(RPM)
0
730
1110
1479
1182
5
730
1110
1479
1186
10
730
1110
1479
1194
15
730
1110
1479
1188
20
730
1110
1479
1224
25
730
1110
1479
1228
30
730
1110
1479
1272
35
929
1306
1673
1406
40
1128
1505
1867
1572
45
1372
1701
2063
1736
50
1525
1896
2255
1952
55
1724
2092
2451
2146
60
1922
2287
2642
2328
65
2121
2483
2838
2522
70
2319
2678
3030
2707
75
2518
2874
3224
2864
80
2717
3069
3418
3120
85
2916
3265
3612
3264
90
3114
3460
3806
3350
95
3114
3460
3806
3416
100
3114
3460
3806
3428
Table 5. Test Data (R1=15kΩ, R2=5.125kΩ, R4=R5=200kΩ, R3, R6 open,)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
4
Application Note 1041
4000
Lower Limit
Target
Upper Limit
Rotating Speed (RPM)
3500
3000
2500
2000
1500
1000
500
0
20
40
60
80
100
Input Duty (%)
Figure 1. Curves of Rotating Speed vs. Input Duty (Example)
VCC
D1
L1
V+
D2
D3
AM4962
1 (1)
C1
1 F
2 (3)
R1
3 (4)
4 (5)
R2
R3
5 (6)
R4
C3
F
OUT2
VCC
VMIN
PWM
OUT1
GND
CT
CF
HIN-
6 (7)
FG
HB
7 (8)
RD
PGND HIN+
14 (15)
V+
13 (14)
12 (13)
R5
11 (12)
10 (11)
9 (10)
R6
Hall
8 (9)
C2
0.47 F
Typical Application (Slope K and Minimum/Maximum Duty Adjustable)
Figure 2. Recommended Application Circuit
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
5
Application Note 1041
Figure 3. AM4962 PCB Layout (Example)
4000
4000
Lower Limit
Target
Upper Limit
AM4962
3000
Lower Limit
Target
Upper Limit
AM4962
3500
Rotating Speed (RPM)
Rotating Speed (RPM)
3500
2500
2000
1500
1000
3000
2500
2000
1500
1000
500
0
20
40
60
80
500
100
0
Input Duty (%)
40
60
80
100
Input Duty (%)
Figure 4. Curves of Rotating Speed vs.
Input Duty (R1, R2, R3, R4, R5, R6 open)
Dec. 2009
20
Figure 5. Curves of Rotating Speed vs.
Input Duty (R1, R2, R3, R5, R6 open, R4=200kΩ)
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
6
Application Note 1041
4000
4000
Lower Limit
Target
Upper Limit
AM4962
3000
Lower Limit
Target
Upper Limit
AM4962
3500
Rotating Speed (RPM)
Rotating Speed (RPM)
3500
2500
2000
1500
1000
3000
2500
2000
1500
1000
500
500
0
20
40
60
80
100
0
Input Duty (%)
Figure 6. Curves of Rotating Speed vs. Input Duty
(R1, R2, R3, R6 open, R4=R5=200kΩ)
Dec. 2009
20
40
60
80
100
Input Duty (%)
Figure 7. Curves of Rotating Speed vs. Input Duty
(R1=15 kΩ, R2=5.125 kΩ, R4=R5=200kΩ, R3, R6 open)
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
7
Application Note 1041
4. Typical Application Examples
4.1 Application Example 1
4.1.1 Requirement of Customer’s Target Product:
(1) Rotating speed remain unchanged under the condition: input duty≤20%
(2) When input duty linearly increases from 20% to 100%, the rotating speed linearly increases accordingly.
4.1.2 Customer’s Specification Data
Input Duty
(%)
Lower Limit
(RPM)
Target
(RPM)
Upper Limit
(RPM)
0
500
750
1000
5
500
750
1000
10
500
750
1000
15
500
750
1000
20
500
750
1000
25
662
917.5
1173
30
822
1083
1344
35
980
1248.5
1515
40
1142
1414
1686
45
1302
1579.5
1857
50
1462
1745
2028
55
1622
1910.5
2199
60
1781
2076
2371
65
1941
2241.5
2542
70
2101
2407
2713
75
2261
2572
2884
80
2421
2738
3055
85
2581
2903.5
3226
90
2740
3069
3398
95
2900
3234.5
3569
100
3060
3400
3740
Table 6. Customer’s Specification Data (Application Example 1)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
8
Application Note 1041
4000
Rotating Speed (RPM)
3500
Lower Limit
Target
Upper Limit
3000
2500
2000
1500
1000
500
0
20
40
60
80
100
Input Duty (%)
Figure 8. Specification Curves of Rotating Speed (Application Example 1)
4.1.3 Recommended Application Circuit
Application Example 1 (Slope K and Minimum/Maximum Duty Adjustable)
Figure 9. Recommended Application Circuit (R1=15kΩ ,R2=5.53kΩ, R5=200kΩ, R3, R4, R6 open, C3=0.22µF)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
9
Application Note 1041
4.1.4 Test Data and Curve Figure
Input Duty
(%)
Lower
Limit
(RPM)
Target
(RPM)
Upper
Limit
(RPM)
FAN1
Rotating
Speed
(RPM)
FAN2
Rotating
Speed
(RPM)
0
500
750
1000
672
669
5
500
750
1000
675
672
10
500
750
1000
678
675
15
500
750
1000
720
705
20
500
750
1000
765
780
25
662
917.5
1173
870
882
30
822
1083
1344
1005
1020
35
980
1248.5
1515
1164
1197
40
1142
1414
1686
1371
1410
45
1302
1579.5
1857
1542
1587
50
1462
1745
2028
1716
1734
55
1622
1910.5
2199
1845
1884
60
1781
2076
2371
2025
2085
65
1941
2241.5
2542
2202
2286
70
2101
2407
2713
2376
2430
75
2261
2572
2884
2592
2610
80
2421
2738
3055
2811
2877
85
2581
2903.5
3226
3030
3120
90
2740
3069
3398
3180
3186
95
2900
3234.5
3569
3210
3270
100
3060
3400
3740
3345
3345
Table 7. Test Data (Application Example 1)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
10
Application Note 1041
4000
Lower Limit
Target
Upper Limit
Fan 1
Fan 2
Rotating Speed (RPM)
3500
3000
2500
2000
1500
1000
500
0
20
40
60
80
100
Input Duty (%)
Figure 10. Curves of Rotating Speed (Application Example 1)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
11
Application Note 1041
4.2 Application Example 2
4.2.1 Requirement of Customer’s Target Product:
(1) Rotating speed remains unchanged under the condition: input duty≤30%
(2) When input duty linearly increases from 30% to 90%, the rotating speed linearly increases accordingly.
(3) Rotating speed remains unchanged when input duty varies from 90% to 100%.
4.2.2 Customer’s Specification Data
Input Duty
(%)
Lower Limit
(RPM)
Target
(RPM)
Upper Limit
(RPM)
0
730
1110
1479
5
730
1110
1479
10
730
1110
1479
15
730
1110
1479
20
730
1110
1479
25
730
1110
1479
30
730
1110
1479
35
929
1306
1673
40
1128
1505
1867
45
1372
1701
2063
50
1525
1896
2255
55
1724
2092
2451
60
1922
2287
2642
65
2121
2483
2838
70
2319
2678
3030
75
2518
2874
3224
80
2717
3069
3418
85
2916
3265
3612
90
3114
3460
3806
95
3114
3460
3806
100
3114
3460
3806
Table 8. Customer’s Specification Data (Application Example 2)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
12
Application Note 1041
4000
Rotating Speed (RPM)
3500
Lower Limit
Target
Upper Limit
3000
2500
2000
1500
1000
500
0
20
40
60
80
100
Input Duty (%)
Figure 11. Specification Curves of Rotating Speed (Application Example 2)
4.2.3 Recommended Application Circuit
Application Example 2 (Slope K and Minimum/maximum Duty Adjustable)
Figure 12. Recommended Application Circuit (R1=15kΩ, R2=5.125kΩ, R4=R5=220kΩ, R3, R6 Open)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
13
Application Note 1041
4.2.4 Test Data and Curve Figure
Input Duty
(%)
Lower
Limit
(RPM)
Target
(RPM)
Upper
Limit
(RPM)
Rotating
Speed
(RPM)
0
730
1110
1479
1182
5
730
1110
1479
1186
10
730
1110
1479
1194
15
730
1110
1479
1188
20
730
1110
1479
1224
25
730
1110
1479
1228
30
730
1110
1479
1272
35
929
1306
1673
1406
40
1128
1505
1867
1572
45
1372
1701
2063
1736
50
1525
1896
2255
1952
55
1724
2092
2451
2146
60
1922
2287
2642
2328
65
2121
2483
2838
2522
70
2319
2678
3030
2707
75
2518
2874
3224
2864
80
2717
3069
3418
3120
85
2916
3265
3612
3264
90
3114
3460
3806
3350
95
3114
3460
3806
3416
100
3114
3460
3806
3428
Table 9. Test Data (Application Example 2)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
14
Application Note 1041
4000
Rotating Speed (RPM)
3500
Lower Limit
Target
Upper Limit
AM4962
3000
2500
2000
1500
1000
500
0
20
40
60
80
100
Input Duty (%)
Figure 13. Curves of Rotating Speed (Application Example 2)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
15
Application Note 1041
4.3 Application Example 3
4.3.1 Requirement of Customer’s Target Product:
(1) When input duty linearly increases from 0% to 100%, the rotating speed linearly rises accordingly.
(2) Slope K=1.
4.3.2 Customer’s Specification Data and Curve Figure.
Input Duty
(%)
Lower Limit
(RPM)
Target
(RPM)
Upper Limit
(RPM)
0
0
0
0
5
0
200
400
10
200
400
600
15
400
600
800
20
600
800
1000
25
787.5
1000
1212.5
30
975
1200
1425
35
1162.5
1400
1637.5
40
1350
1600
1850
45
1537.5
1800
2062.5
50
1725
2000
2275
55
1912.5
2200
2487.5
60
2100
2400
2700
65
2287.5
2600
2912.5
70
2475
2800
3125
75
2662.5
3000
3337.5
80
2850
3200
3550
85
3037.5
3400
3762.5
90
3225
3600
3975
95
3412.5
3800
4187.5
100
3600
4000
4400
Table 10. Customer’s Specification Data (Application Example 3)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
16
Application Note 1041
4500
4000
Lower Limit
Target
Upper Limit
Rotating Speed (RPM)
3500
3000
2500
2000
1500
1000
500
0
-500
0
20
40
60
80
100
Input Duty (%)
Figure 14. Specification Curves of Rotating Speed (Application Example 3)
4.3.3 Recommended Application Circuit
Application Example 3 (Slope K and Minimum/Maximum Duty Adjustable)
Figure 15. Recommended Application Circuit
(R1, R2, R4, R5, R6 open, R3=750kΩ, C1=1µF, C2=0.47µF, C3 open)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
17
Application Note 1041
4.3.4 Test Data and Curve Figure
Input Duty
(%)
Lower
Limit
(RPM)
Target
(RPM)
Upper
Limit
(RPM)
Rotating
Speed
(RPM)
0
0
0
0
0
5
0
200
400
150
10
200
400
600
360
15
400
600
800
600
20
600
800
1000
870
25
787.5
1000
1212.5
1080
30
975
1200
1425
1290
35
1162.5
1400
1637.5
1530
40
1350
1600
1850
1710
45
1537.5
1800
2062.5
1920
50
1725
2000
2275
2100
55
1912.5
2200
2487.5
2280
60
2100
2400
2700
2490
65
2287.5
2600
2912.5
2670
70
2475
2800
3125
2820
75
2662.5
3000
3337.5
3000
80
2850
3200
3550
3150
85
3037.5
3400
3762.5
3300
90
3225
3600
3975
3450
95
3412.5
3800
4187.5
3600
100
3600
4000
4400
3750
Table 11. Test Data (Application Example 3)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
18
Application Note 1041
4500
4000
Lower Limit
Target
Upper Limit
AM4962
Rotating Speed (RPM)
3500
3000
2500
2000
1500
1000
500
0
-500
0
20
40
60
80
100
Input Duty (%)
Figure 15. Curves of Rotating Speed (Application Example 3)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
19
Application Note 1041
4.4 Application Example 4
4.4.1 Requirement of Customer’s Target Product:
Keep maximum speed regardless of the input duty (0% to 100%)
4.4.2 Customer’s Specification Data and Curve Figure.
Input Duty
(%)
Lower Limit
(RPM)
Target
(RPM)
Upper Limit
(RPM)
0
3014
3360
3706
5
3014
3360
3706
10
3114
3460
3806
15
3114
3460
3806
20
3114
3460
3806
25
3114
3460
3806
30
3114
3460
3806
35
3114
3460
3806
40
3114
3460
3806
45
3114
3460
3806
50
3114
3460
3806
55
3114
3460
3806
60
3114
3460
3806
65
3114
3460
3806
70
3114
3460
3806
75
3114
3460
3806
80
3114
3460
3806
85
3114
3460
3806
90
3114
3460
3806
95
3114
3460
3806
100
3114
3460
3806
Table 12. Customer’s Specification Data (Application Example 4)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
20
Application Note 1041
3800
Rotating Speed (RPM)
3600
3400
3200
3000
Lower Limit
Target
Upper Limit
2800
0
20
40
60
80
100
Input Duty (%)
Figure 16. Specification Curves of Rotating Speed (Application Example 4)
4.4.3 Recommended Application Circuit
Application 4 (Slope K and Minimum/Maximum Duty Adjustable)
Figure 17. Recommended Application Circuit (R1, R2, R3, R5, R6 Open, R4 short)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
21
Application Note 1041
4.4.4 Test Data and Curve Figure
Input Duty
(%)
Lower
Limit
(RPM)
Target
(RPM)
Upper
Limit
(RPM)
Rotating
Speed
(RPM)
0
3014
3360
3706
3410
5
3014
3360
3706
3358
10
3114
3460
3706
3450
15
3114
3460
3806
3390
20
3114
3460
3806
3420
25
3114
3460
3806
3460
30
3114
3460
3806
3380
35
3114
3460
3806
3350
40
3114
3460
3806
3345
45
3114
3460
3806
3390
50
3114
3460
3806
3348
55
3114
3460
3806
3370
60
3114
3460
3806
3390
65
3114
3460
3806
3348
70
3114
3460
3806
3400
75
3114
3460
3806
3390
80
3114
3460
3806
3408
85
3114
3460
3806
3429
90
3114
3460
3806
3360
95
3114
3460
3806
3390
100
3114
3460
3806
3408
Table 13. Test Data (Application Example 4)
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
22
Application Note 1041
3800
Rotating Speed (RPM)
3600
3400
3200
3000
Lower Limit
Target
Upper Limit
AM4962
2800
0
20
40
60
80
100
Input Duty (%)
Figure 18. Curves of Rotating Speed (Application Example 4)
Note 2:
1) D2 and D3 are recommended to be used when the current in coil L1 is higher than 300mA in Figure 2,
Figure 9, Figure 12, Figure 15.
2) VCC=12V, unless otherwise specified.
Dec. 2009
Rev. 1. 0
BCD Semiconductor Manufacturing Limited
23
```