ZN423 ABSOLUTE MAXIMUM RATINGS Reference current per: Operating temperature range Storage temperature range 20mA Oto +70C -55 to +125C -65 to +165C ELECTRICAL CHARACTERISTICS (at T,,,,= 25C unless otherwise specified). Parameter Symbol] Min. | Typ. | Max. | Unit Note Output voltage Vrer 1.2 | 1.26] 1.32] V Slope resistance Rrer - 0.5 1.0 | Q 1 Reference current lree 1.5 - 12 mA Temperature coefficient - 30 - ppm/C Shaping capacitance Cs 0.1 - - pF External resistance Rexr 100 - - Q 2 R.M.S. noise voltage 1Hz to 10kHz - 6 ~ pV Power supply rejection ratio PSRR - 60 - dB 3 Vaer = 1.26V lagp = 2.5mMA Veco = 5.0V Veer drift at 125C oVReF - 10 = ppm/1000 hours - 100 - ppm/year Note 1) Ipep =5mA Note 2) Rext = (Voc 1Vper)/Irer Note 3. PSRR= Rex /RrerZN423 Derating curve Reference current Ipep (max.) v operating temperature. {2 They (Max) mA 0 -55 -40 -20 0 +20 +40 +60 +80 +100 +125 Operating temperature C Slope resistance v frequency (Igg = 5MA). _ S OUTPUT RESISTANCE .n oa o wt ~ 2 o Frequency - Hz 3-11ZN423 APPLICATIONS 1. 5V, 0.5A power supply. 01 O+5V ZS170 F 100uF R2| [620 cs +8k R3 10V ZN423 D3 {_"} a 4N4) \ ov + 6 N424 ZNL2 at ca Loa 6 2 i R q 7-SpF Q 330 2N3055 : Tr2 No g {28170 02 Z7x108 r + 33k 1 2200uF S=c1 Rs] }1 2 10 T I ] WATT ZN423/06/86 Fig. 1 This circuit is essentially a constant current source modified by the feedback components Ry and R3 to give a constant voltage output. The output of the ZN424E need only be 2V above the negative rail, by placing the load in the collector of the output transistor Tro. Current circuit is achieved by Tr, and Rs. This 3-12 simple circuit has the following performance characteristics: Output noise and ripple (full load) = 1mMV r.m.s. Load regulation (0 to 0.5A)=0.1%. Temperature coefficient = + 100ppm/C. Current limit =0.65A.2. 5V, 1.0A power supply ZN423 N C3 47uF uaF 2N423/06 /86 Fig. 2 The circuit detailed in Fig. 2 provides improved The output voltage is given by: (Rg + Ra). Vrer performance over that in Fig. 1. This is achieved R by feeding the ZN423 reference and the ZN424E error amplifier from a rnore stable source, derived from the emitter-follower stage (Tr,}. The supply rejection ratio is improved by the factor R,/R,, where R, is the slope resistance of D3. 3 and may adjusted by replacing R3 with a 220 and a 5000 preset potentiometer. The output is protected against short circuits by Tr2 setting a current limit of 1.6A.ZN423 3. Oto 12V, 1A power supply N C4 07 Oe RI] /2-2k ZTX500 Tri R7 1k ZN424E cs output contra. | OF * 727x500 Fig. 3 ZTX108 Te2 CURRENT 2N3055 TTr R8 0:47 100 2 WATTS c 47uF 8 OTE *c7 ie 2N423/06 /86 The above circuit provides a continuously variable, highly stable voltage for load currents up to 1A. The output voltage is given by: (Vas + Vee) Vo = Vrer: 4 and is controlled by Vag and Vag which should be high quality components (preferably wire wound}. The emitter follower stages Tr, and Tr, buffer the bias and reference from the output stage. The negative rail allows the output to operate down to OV. The current limit stage monitors output current through R,5. As the potential across Ris increases due to load current, Tr, conducts and supplies base current for Tr3, thus diverting part of the output from the ZN424E, via Tr3 to Trg. Shaping is achieved by the network Cz, Rg together with the output decoupling capacitors which also maintain low output resistance at frequencies above 100kHz. The power supply has the following performance characteristics: Output noise and ripple (full load) < 100nV rm.s. Qutput resistance (0 to 1A) 1mQ Temperature coefficient + 100ppm/C4. Variable current source, 100mA to 2A. ZN423 > g 20V MAX R2{ {680 R 6V MIN 0-5] F---] 10 s SET CURRENT - zNz3 a + ue ou = 2N 423/06 /86 Fig. 4 In this circuit the output current is set by the resistor R in the collector of Tr2, which may be switched to offer a range of output currents from 100mA to 2A with fine control by means of VR3 which varies the reference voltage to the non- inverting input of the ZN424E. The feedback path from the output to the inverting input of the ZN424 maintains a constant voltage across R, equal to (Vcc V,,) and hence a constant current to the load given by (Vec Vin)/R.ZN423Precision voltage reference source ZN423 FEATURES Low voltage Low temperature coefficient Very good long term stability Low slope resistance Low RMS noise Tight tolerance High power supply rejection ratio Two pin package DESCRIPTION The ZN423 is a monolithic integrated circuit utilising the energy bandgap voltage of a base- emitter junction to produce a precise, stable, regulator source of 1.26V. This is derived via an external dropping resistor for supply voltages of 1.5V upwards. The temperature coefficient of the ZN423, unlike conventional Zener diodes, remains constant with reference current. The noise figure associated with breakdown mechanisms is also considerably reduced. pVRer BAND GAP REFERENCE o -ve J 0 -ve 2N423/06/66 Circuit diagram Note: on special requests this device is also available in E-Line package Package outline 5,620,258 4,720,158 6,8:0,5 2,5PC0 OK. . o ase +Ve-(0::2.}+ Ve x 7 Wry, See 2 lead TO-18 Pinning configuration Dimensions in millimetres