Allied Motion's BL 21 series of 24 mm dia., 2 W small brushless DC motors are extremely compact, yet incorporate integrated drive electronics. BL series motors are also available as motor-only models without drive electronics onboard (EE models). The BL 21 series employ an external rotor and iron core stator to minimize cogging and maximize output torque. High quality components ensure BL motor life exceeds 20,000 hours. The BL 21 series are a good choice for many types of small pumps, laser scanners, gas analyzers and small high performance fans and blowers. Features & Benefits As simple to control as a DC motor: 2-wire brushless design requires only a DC voltage to operate Reverse supply voltage protection Low EMI: Comply with EN55011, EN55022, EN500821 (with supply filter capacitor ) Low audible noise — ideal for use in noise sensitive applications Options Special shaft diameter and machining Customized mounting flange  Protection class up to IP54 5-wire versions for speed adjustment, speed output and direction change

Small precision 24 mm dia. brushless DC motors with integrated drive electronics (EB models) Rated up to 2 W continuous power output and 2500 RPM nominal speed Motor-only models without drive electronics available (EE models)

Model	CW CCW	4322 016+ 4322 016+	21511 21521	21531 21541
Construction Type			Outer rotor, rare-earth magnet, wound iron-core stator
Nominal Voltage		V	12	24
Voltage Range		V	5 - 17	9 - 28
Max. Output Power1		W	2	2
Nominal Torque		mNm (oz-in)	4 (0.57)
Maximum Continuous Torque1		mNm (oz-in)	6 (0.85)
Nominal Speed		RPM	2500
No-Load Speed		RPM	4500
Nominal Current		mA	205	108
Maximum Continuous Current1, 2		mA	280	150
No-Load Current		mA	40	30
Torque Constant		mNm/A (oz-in/A)	27.6 (3.91)	56.2 (7.96)
Rotor Inertia		kgm2 (oz-in-s2)	0.77E-6 (1.09E-4)
Mechanical Time Constant		ms	36
Thermal Resistance Winding-Housing		°C/W	5.3
Thermal Resistance Housing-Ambient		°C/W	25.5
Weight		g (oz)	30 (1.06)
Protection		-	IP42
Compatible Gearboxes (option)3		-	P22A, S22A
Notes: Values valid for nominal voltage and Tamb = 22 ºC 1) Motor mounted to heatsink 2) At Tamb = 50ºC, 230 mA, 125 mA, respectively 3) Requires 2 mm dia. motor shaft

Wiring Connections
Color	Function
Red	Supply
Blu	Common
Wire size: AWG 26

BL 21 EB 12V (two wire version)




BL 21 EB 24V (two wire version)

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Model	Type	Dimensions mm (in)	Torque Nm (lb-in)	Ratio
P22A	Planetary	22 (0.87)	0.7 (6.2)	4:1 - 1140:1
S22A	Spur	20.3 (0.8)	0.1 (0.88)	8:1 - 648:1

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Item No.	Description	Type	Size
N/A	BL Series Precision BLDC Motors Specifications Brochure	PDF	518 kB
N/A	BL 21 EB Dimension Drawing	DWG	103 kB
TO-BLO01	Technology Overview: Outer Rotor Brushless DC Motors (BLO Series)	PDF	355 kB