M61880FP Laser Diode Driver/Controller REJ03F0068-0100Z Rev.1.0 Sep.19.2003 Description The M61880FP is a laser diode driver/controller that performs drive and laser power control of a type of semiconductor laser diode in which the semiconductor laser diode anode and monitoring photodiode cathode are connected to the stem. The M61880FP has a sink type laser drive current output pin, is capable of high-speed switching at up to 200 Mbps, and can drive a laser diode at a maximum drive current of 100 mA (drive current = switching current + bias current). A high-speed sample-and-hold circuit is incorporated, enabling a self-APC* system to be implemented without the need for laser power control from outside. * Automatic Power Control Features • On-chip self-APC sample-and-hold circuit High-speed sampling circuit APC 1% variance response time = 1 µs (C = 0.047 µF) High-impedance hold circuit (1% error or less at C = 0.047 µF, t = 1 ms) • High-speed switching (200 Mbps max.) • High drive current (100 mA max.) • Bias current settable (40 mA max.) • 5 V single power supply Application Semiconductor laser diode application systems (LBPs, PPCs, optical communications, measuring instruments, etc.) Pin Configuration (Top View) Switching current setting resistance connection pin Ground 1 RS 1 20 VCC2 Power supply 2 Laser current load output 19 RB 3 18 NC VB 4 17 Reference voltage output Vref 5 Reference voltage input Vr 6 Hold capacitance connection pin CH 7 Sample-and-hold control input S/H 8 Power supply 1 M61880FP GND1 2 Bias current setting resistance connection pin Bias current setting voltage input RO LD Laser current output 16 GND2 Ground 2 15 PD Monitoring photodiode current input 14 DATA Switching data input 13 ENB Laser current enable input 9 12 2RM NC 10 11 1RM VCC1 Monitoring load resistance connection pins Package: 20P2N-A NC: Not connected Rev.1.0, Sep.19.2003, page 1 of 20 M61880FP Block Diagram Monitoring photodiode current input Monitoring load resistance connection pins Laser current output 1RM 2RM PD LD 11 12 15 17 Reference voltage output Laser current load resistance Vref RO 5 19 IPD Vr 6 Comparator Sample-and-hold control input S/H 8 Sample-and-hold circuit Hold capacitance connection pin CH 7 Switching current setting resistance connection pin RS 1 Bias current setting voltage input VB 4 Bias current setting resistance connection pin RB 3 Reference voltage input Reference voltage source Current switching circuit Switching current source (Isw) 100mA max∗ Bias current source (IB) 40mA max∗ 14 DATA Switching data input 9 VCC1 Power supply 1 20 VCC2 Power supply 2 2 GND1 Ground 1 16 GND2 Ground 2 13 ENB Laser current enable control input ∗ISW+IB=100mA (max) VCC1, GND1: For IC internal analog system VCC2, GND2: For IC internal digital system Function Overview The M61880FP is a semiconductor laser diode driver/controller that automatically performs drive and laser power control of a type of semiconductor laser diode in which the semiconductor laser diode (LD) anode and monitoring photodiode (PD) cathode are connected to the stem. Laser power control operation is performed by connecting an external capacitance to the CH pin and applying a reference voltage to the Vr pin. The PD current resulting from LD light emission flows to a resistance connected between 1RM and 2RM, and generates a voltage (VM). This VM voltage is compared with the voltage applied to the Vr pin, and if VM < Vr, the current from the CH pin is taken as a source current and an external capacitance is charged. If VM > Vr, the current from the CH pin is taken as a sink current and the external capacitance charge is discharged. This operation is performed when S/H input = “L” and DATA input = “L” (sampling). When S/H input = “H”, the CH pin goes to the high-impedance state (hold) irrespective of the state of VM, Vr, and the DATA input. The LD drive current is composed of switching current ISW controlled by DATA input and LD bias current IB unrelated to the DATA input state. Rev.1.0, Sep.19.2003, page 2 of 20 M61880FP Pin Description Pin No. Symbol Name Function 1 Rs Switching current setting resistance connection pin Connects switching object current (ISW) setting resistance to GND. 2 GND1 Ground 1 Internal analog GND 3 RB Bias current setting resistance connection pin Connects bias current (IB) setting resistance to GND. Leave this pin open when IB is not used. 4 VB Bias current setting voltage input Bias current value (IB) is set by applying a voltage to this pin. Leave this pin open when IB is not used. 5 Vref Reference voltage output M61880 internal reference voltage (1.5 V typ.) output pin 6 Vr Reference voltage input 7 CH Hold capacitance connection pin Connected to non-reversed input pin of comparator in sample-andhold circuit. Connect this pin to Vref pin when using M61880 internal reference voltage. Connects hold capacitance to GND. This pin is connected to sample-and-hold circuit output and ISW current source input in M61880. 8 S/H 9 Vcc1 Sample-and-hold control input Power supply 1 10 11, 12 NC 1RM 2RM NC Monitoring load resistance connection pins Not connected to internal circuitry. Connects load resistance for converting monitor photodiode current to voltage between 1RM and 2RM. (1RM pin is connected to GND in IC.) 13 ENB Laser current enable input 14 DATA Switching data input When “H”, LD drive current source circuit is turned off. Also, CH pin is forcibly fixed at “L” level. ISW+IB current flows to laser diode when “+”, and IB current when “H”. 15 PD 16 GND2 Monitoring photodiode current input Ground 2 Internal digital GND 17 18 LD NC Laser current output NC Connects semiconductor laser diode cathode. Not connected to internal circuitry. 19 20 RO Vcc2 Laser current load output Power supply 2 Connects laser current load resistance to Vcc. Internal digital power supply. Connected to positive power supply (+5 V). Sampling when “H”, hold when “L” Internal analog power supply. Connected to positive power supply (+5 V). Connects monitor photodiode anode. Operation 1. Laser drive current setting method The laser drive current consists of switching current ISW + bias current IB. (1) Switching current ISW setting method a. Decide the maximum current value ILD(MAX) to flow in the laser diode (LD). This is decided taking account of the LD type, dispersion, temperature changes, secular changes, etc. b. Find ISW (initial set value) from the following equation. ISW (initial set value) = ILD(MAX)/1.9 c. Find switching current setting resistance RS from the following equation. RS [kΩ] 30 × Vref (1.5V) [V] / ISW (initial set value) [mA] In this case the LD current can be controlled in a range of 10% to 90% of ISW (initial set value). Rev.1.0, Sep.19.2003, page 3 of 20 M61880FP (2) Bias current IB setting method Bias current IB [A] is set by deciding bias current setting resistance RB and bias current setting voltage VB. IB [A] VB [A] / RB [Ω] where 1.2 V ≤ VB ≤ Vcc - 2.7V, IB (max.) = 40mA 2. Switching operation When DATA = “L”, the LD drive current is ISW+IB, and when DATA = “H”, the LD drive current is IB. 3. ENB input In laser drive current control by DATA input, the drive current to the laser is controlled when the M61880 internal current source is on, while control by ENB turns LD drive current source operation on/off. Power is turned on when ENB = “H”, and the current secure is turned off when ENB = “L”. When ENB = “H”, the CH pin is forcibly fixed at the “L” level, and the capacitor connected to the CH pin is forcibly discharged. When changing the ENB pin from “H” to “L”, in order to prevent an abnormal current from flowing in the LD, drive the DATA pin to the “H” state, then wait 10 µsec or more after the ENB pin changes from “H” to “L” before changing the DATA pin from “H” to “L”. 4. Internal reset operation The M61880 incorporates a reset circuit for preventing an overcurrent in the laser when power is turned on. In the range VCC < 3.5 V (typ.), the internal current source is turned off and the CH pin is forcibly fixed at the “H” level. 5. RO pin The RO pin connects the drive current load resistance, and a currently virtually equal to ISW flows from this pin. The load resistance is connected between this pin and VCC, thereby reducing power consumption in the IC. For reasons relating to circuit operation, the voltage at this pin must be 2.5 V or higher. Therefore, if the maximum value of ISW is designated ISW(max.), maximum value RO(max.) of load resistance RO is as follows: RS (max.) [Ω] = Vcc (min.) [V] - 2.5 [V] ISW (max.) [A] For example, if VCC(min.) = 4.75 V and ISW(max.) = 100 mA, RO(max.) = 22 Ω. That is to say, when the RS value is set so that ISW is a maximum of 100 mA, RO must not exceed 22Ω. 6. Sample-and-hold circuit (1) Overview of circuit operation The operation of the sample-and-hold circuit incorporated in the M61880 is outlined below. The PD current resulting from LD light emission flows to resistance RM connected between 1RM and 2RM, and generates a voltage (VM). This VM voltage is compared with the voltage applied to the Vr pin, and if VM < Vr, the current from the CH pin is taken as a source current and an external capacitance is charged. If VM > Vr, the current from the CH pin is taken as a sink current and the external capacitance charge is discharged. This operation is performed when S/H input = “L” and DATA input = “L” (sampling). When S/H input = “H”, the CH pin goes to the high-impedance state (hold) irrespective of the state of VM, Vr, and the DATA input. Rev.1.0, Sep.19.2003, page 4 of 20 M61880FP Charging constantcurrent source Comparator Reference voltage input SW1 Output (CH pin) RM resistance generation voltage Control circuit S/H Sample-and-hold control input SW2 CH External capacitance Discharging constantcurrent source ENB Tr1 Conceptual Diagram of Sample-and-Hold Circuit Operation Function Table Input ENB Switch State S/H DATA VM, Vr SW1 SW2 Tr1 Output (CH Pin) H X X X OFF OFF ON Fixed at “L” L L H L X H X X OFF OFF OFF OFF OFF OFF High-impedance state (hold) High-impedance state (hold) L VM < Vr ON OFF OFF Current source (sample) VM > Vr OFF ON OFF Current sink (sample) X: Don’t Care (2) APC timing chart An example of a timing chart of APC operation by means of the sample-and-hold control signals is shown below. In this example, a case is shown in which the direction of the CH pin leakage current in the hold state is assumed to be the direction of flow to the M61880 (forward direction). Power supply ENB input Sample S/H input Sample Hold Hold Sample DATA input ∆ILD Laser drive current Example of Sample-and-Hold Type APC Circuit Operation Timing Chart Rev.1.0, Sep.19.2003, page 5 of 20 Hold M61880FP 7. VCC and GND pins Power supply related pins are the VCC1 and VCC2 pins and the GND1 and GND2 pins. In terms of the internal circuitry , these are connected as follows. (Basically, a single power supply should be used.) VCC1, GND1: Connected to analog system. VCC2, GND2: Connected to digital system. The main points to be noted with regard to actual wiring are as follows. (1) Make the wiring as wide as possible and avoid lengthy, circuitous wiring. (2) Locate an electrolytic capacitor for voltage stabilization close to VCC1 and GND1. (3) Locate a bypass capacitor close to VCC2 and GND2. Also ensure that M61880 power is supplied while laser diode power is being supplied. Note on Wiring of Peripheral Elements Peripheral elements necessary for M61880 operation should be located as close as possible to the M61880. Power Consumption Calculation Method M61880 power consumption P is given approximately by the following equation: P = Icc.×.Vcc.+.I(RO) ×.V(RO) +.I(LD) ×V(LD) where V(RO): RO pin voltage V(LD): LD pin voltage I(RO): RO pin load current I(LD): LD pin load current For example, when VCC = 5.25 V, V(RO) = V(LD) = 2.5 V, and I(RO) = I(LD) = 100 mA, the power consumption values when the laser is on and off are as follows. (1) When laser is on, (DATA = “L”, ICC = 55 mA) PON = 55.×.5.25.+.0 + 100 ×.2.5 = 538.8 (mW) (2) When laser is off, (DATA = “H”, ICC = 55 mA) PON = 55.×.5.25.+.100 ×.2.5 = 538.8 (mW) Rev.1.0, Sep.19.2003, page 6 of 20 M61880FP Absolute Maximum Ratings Item Symbol Ratings Unit Power supply voltage VCC -0.3 to +5.5 V Input voltage CH, Vr VI -0.3 to Vcc V Output voltage DATA, ENB, S/H RO V Vo -0.3 to Vcc -0.3 to Vcc Switching current Bias current Isw IB 120 50 mA mA Power consumption Pd 980 mW Storage temperature Tstg -60 to +150 °C Conditions When mounted on board. When Ta = 25°C (Note) Note: When Ta ≥ 25°C, 9.8 mW/°C derating should be applied. Recommended Operating Conditions (Unless otherwise noted, Ta = -20ºC to +70ºC)Absolute Maximum Ratings Limits Item Symbol Min. Typ. Max. Unit Power supply voltage Vcc 4.75 5.0 5.25 V Switching current Bias current Isw IB 100 40 mA mA Operating ambient temperature Topr 70 °C Note: ISW+IB ≤ 100 mA Rev.1.0, Sep.19.2003, page 7 of 20 −20 M61880FP Electrical Characteristics (Unless specified otherwise noted, VCC = 5 V ±5%, Ta = -20ºC to +70ºC) Limits Item Symbo l Min. 2.0 2.0 Typ. Max. Unit Test Conditions “H” input voltage DATA ENB, S/H VIH “L” input voltage DATA ENB, S/H VIL Reference voltage input Reference voltage output Vr Vr 0.35 Vref Vref 1.4 Operating voltage range Effective voltage upper limit LD VLD 2.5 CH VI 2.7 “H” output voltage “L” output voltage CH VOH Vcc−1.6 CH VOL Input voltage DATA, ENB II Switching current (Note) Bias current (Note) LD Isw LD IB Load charge current Load discharge current CH Icg −0.2 −0.1 CH Idg 0.66 1.0 Off-state output current Off output current CH Ioz −0.5 LD LOFF 50 µA ENB = “L”, DATA = “H”, Isw = 50mA Icc 43 50 63 µA mA 43 63 ENB = “H”, DATA = “L”, Isw = 50mA Vcc = 5.25V, ENB = DATA = 0V 0V, CH = 2.5V, DATA = 4.5V VB = 1.5V, Rs = 820Ω, RB = 75 Ω Ro = LD = 5.0V Temperature coefficient V V 0.8 0.8 V V 1.5 2.0 V 1.5 1.6 V Io = ±10µA mV/°C Ta = −20 to 25°C Ta = 25 to 70°C V ILD = 75mA 0.1 −0.1 Vcc 3.0 V V ENB = “L”, IOH = (−0.6mA) 0.6 V ENB = “L”, IOL = (0.6mA) 20 µA mA VI = 2.7V VI = 0.4V 75 mA CH = 3.5V, Rs = 1.2kΩ, VLD = 3V 20 mA VB = 1.4V, RB = 70kΩ, VLD = 3V −0.66 mA ENB = “L”, Vo = (0.6 to Vcc−1.6V) 2.0 mA ENB = “L”, Vo = (0.6 to Vcc−1.6V) 0.5 µA Vo = 2.0 to 3.0V, hold state −0.2 Power supply current * Reference values are values when Ta = 25ºC and VCC = 5 V. Note: These items indicate input voltage/output current conversion characteristics. The M61880 should be used with ISW and IB within the Specification Value range given in “Recommended Operating Conditions.” Rev.1.0, Sep.19.2003, page 8 of 20 M61880FP Switching Characteristics (Unless specified otherwise noted, Ta = 25ºC and VCC = 5 V) Test Pins Item Symbol Operating frequency LD current rise time (*) fop tr LD current fall time (*) APC circuit response time 1 Limits Input Output DATA voltage LD current tf DATA voltage LD current 1.0 nsec tRP1 Vr voltage LD current 1 µsec tRP2 Vr voltage LD current 3 µsec Circuit on time tON ENB voltage LD current 350 µsec Circuit off time tOFF ENB voltage LD current 5 µec (1% variance response time) APC circuit response time 2 (50% variance response time) Rev.1.0, Sep.19.2003, page 9 of 20 Min. Typ. Max. Unit 100 1.0 2.0 2.0 Mbps nsec Test Conditions ILD (H) = 50mA, ILD (L) = 0mA Rs = 840Ω, CH = 0.047µF, APC adjustment; RM = adjustment (CH = 2.5V), Vr = 1.5V (Note 1) ILD (H) = 50mA, Rs = 840Ω, CH = 0.047µF, DATA = 0V APC adjustment; RM = adjustment (CH = 2.5V), Vr = 1.5V ± 0.5% (Note 1) ILD (H) = 50mA (Note 2) ILD (H) = 50mA (Note 2) M61880FP Note 1: Test Circuit 20Ω Oscilloscope (input) VCC 0.047µF CH P.G. RO Vr PD RS LD PD Oscilloscope (output) ILD 840Ω 50Ω LD Current probe Oscilloscope (input) DATA S/H ENB 1RM RM 2RM GND Other pins open P.G. 50Ω DATA voltage LD voltage 1.5V 90% 90% 10% tr 10% tf 0% ILD (H) ILD (L) 1.5 V ± variance amount Vr voltage TRP1 (TRP2) TRP1 (TRP2) ILD (H) 90% LD current 10% Rev.1.0, Sep.19.2003, page 10 of 20 ILD (L) M61880FP Note 2: Test Circuit 20Ω VCC CH RO PD LD Oscilloscope (output) 0.047µF 1.5V Vr PD RS LD ILD 840Ω Current probe S/H DATA 1RM RM 2RM Other pins open Oscilloscope (input) ENB GND P.G. 50Ω tr=tf=6ns 3V EBN voltage 1.5V 1.5V 0V TON TOFF ILD (H) 90% LD current Rev.1.0, Sep.19.2003, page 11 of 20 10% ILD (L) M61880FP Application Example 1. Example of sample-and-hold type self-APC circuit Connected to prevent overshoot and undershoot when LD current rises and falls. Optimal values depend on the type of laser used and the board pattern. 5V VCC 100pF 36Ω 5V 10Ω Vcc2 Digital 20 RO NC 19 18 GND2 Digital LD 17 16 PD 15 DATA ENB 14 13 2RM 1RM 12 11 TTL input COMP ISW Charge/ discharge control circuit 2.5V IB Reference voltage 50k 1.5V 1 2 RS 1.5kΩ 3 GND1 Analog 4 RB 150Ω 5 VB 6 Vref 7 Vr 8 CH 9 S/H 10 Vcc1 NC Analog 0.047µF 5V 2. Example of controlling sample-and-hold circuit by means of DATA signal When the M61880 is used in optical communications, etc., (when the S/H signal cannot be supplied), the DATA signal can be used as a sample-and-hold control signal. In this case, the S/H pin should be fixed at “L”. If value CH of the hold capacitor connected to the CH pin is 0.047µF, switching at around 20 Mbps is possible. 3. Examples of varying LD switching drive current by means of external control (1) Varying the monitoring load resistance value (resistance connected between pins 11 and 12) The LD drive current can be varied by varying the resistance between pins 11 and 12 in the circuit in 1. above. (2) Varying the voltage applied to the Vr pin The LD drive current can be varied by applying an external voltage (within the reference voltage input range) to pin 6 in the circuit in 1. above. A maximum multiplication factor of 2/0.35 = 5.7 times can be obtained as the LD drive current ratio in this case. Rev.1.0, Sep.19.2003, page 12 of 20 M61880FP 4. Example of sample-and-hold type self-APC circuit (Controlling two laser diodes) 100pF 36Ω 5V 10Ω RO Vcc2 Digital 20 NC 19 18 GND2 Digital LD 17 16 PD DATA ENB 2RM 1RM 14 13 12 11 15 M61880FP-1 TTL input COMP ISW Charge/ discharge control circuit 2.5V IB Reference voltage 50k 5V VCC 1.5V 1 LD1 2 RS 3 1.5kΩ 4 RB 150Ω GND1 Analog 5 VB 6 7 Vref Vr 8 CH S/H 0.047µF 9 10 Vcc1 NC Analog Rvr1 PD 5V LD2 100pF 36Ω 5V Rm 10Ω RO Vcc2 Digital 20 NC 19 18 GND2 Digital LD 17 16 PD DATA 15 14 ENB 2RM 13 1RM 12 11 M61880FP-2 TTL input COMP Charge/ discharge control circuit ISW 2.5V IB Reference voltage 50k 1.5V 1 2 RS 1.5kΩ 3 GND1 Analog 4 RB 150Ω 5 VB 6 Vref 7 Vr 8 CH S/H 0.047µF 9 Rvr2 5V Sample-and-Hold Timing M61880FP-1 HOLD S/H input HOLD M61880FP-2 S/H input Start of data transfer Sampling Rev.1.0, Sep.19.2003, page 13 of 20 10 Vcc1 NC Analog M61880FP Sample-and-Hold Type APC Operation A timing chart for a case where a sample-and-hold type APC circuit is configured using an M61880FP (Figure 1) is shown in Figure 2 on the following page. The operation of a sample-and-hold type APC circuit will be described here using the timing chart in Figure 2. It is assumed that the laser drive current is set to 50 mA (bias current = 0 mA), and the values shown in Figure 1 are used as constants required for calculation purposes. 5V VCC 100pF 36Ω 5V 10Ω Vcc2 Digital 20 IPD RO NC 19 18 GND2 Digital LD 17 16 PD 15 DATA ENB 14 13 RM 2RM 12 1RM 11 TTL input COMP ISW Charge/ discharge control circuit 2.5V IB Reference voltage 50k 1.5V 1 2 RS 3 GND1 RB Analog 4 VB 5 6 Vref 7 Vr 8 CH 9 S/H 10 Vcc1 NC Analog 0.047µF 5V Figure 1 Example of Sample-and-Hold Type APC Circuit Application 1. Initial sampling period (T1) When sampling starts, the CH pin voltage is 0 V, and therefore the laser diode (LD) is not emitting light. Consequently, the voltage of the COMP input pin (pin 12) is also 0 V. Next, COMP starts charging the hold capacitor connected to CH (current also starts flowing in the LD in proportion to the rise of the CH pin voltage, and the pin 12 voltage also rises), and charging is performed until the pin 12 voltage reaches comparison voltage Vr. In this case, the CH pin voltage rises from 0 V to VCH due to the M61880FP’s CH pin load charge current (Icg). Time t required for this is given by the following equation. t= CH × VCH Icg ............................ Equation (1) In Equation (1), if CH = 0.047µF, VCH = 2.5 V, and Icg = 0.66 mA (*), then t = 178µs. * Minimum Icg specification value in “Electrical Characteristics” in this Specification. Rev.1.0, Sep.19.2003, page 14 of 20 M61880FP 2. Hold periods (T2, T4) In these periods, the CH pin goes to the high-impedance state. However, the charge current does not become absolutely 0, and a slight leakage current is present. The hold capacitor is charged or discharged by the CH pin off-state leakage current (Ioz). Assuming that a leakage current (Ioz) is generated in the direction in which the hold capacitor is discharged, the change in the CH pin current (∆V) is given by the following equation. ∆V = Ioz (0.5µA) × T2 (4) CH × (0.047µF) ............................ Equation (2) (T2(4) is the hold time.) When the CH pin voltage decreases by ∆V, the laser drive current also decreases. 3. Sampling periods (T3, T5) In these periods, the LD light quantity that changed during a hold period (T2, T4) is corrected. Taking only the influence of the CH pin leakage current into consideration (actually, LD temperature variations also have an effect), making substitutions of Ioz = 0.5µA, T = 1 ms, and CH = 0.047µF in Equation (2) gives a result of ∆V = 10 mV. The time required to compensate for this ∆V value (10 mV) is given by the following equation. t= CH × ∆V Icg ............................ Equation (3) From Equation (3), t = 0.7µs. Power supply ENB input S/H input Sample Sample Hold Hold Sample DATA input ∆ILD Laser drive current T1 T2 T3 T4 T5 Figure 2 Sample-and-Hold Type APC Circuit Operation Timing Chart Rev.1.0, Sep.19.2003, page 15 of 20 Hold M61880FP Description of Laser Switching Current Setting Circuit VCC Switching current initial setting circuit 1:1 ISW1 D1 D2 VB ISW2 2XISWO 2XISWO I1 AMP1 1.5V I2 Q1 Q2 ISW2 V1 V2 Vd ISW RS VCC 2.5V 2kΩ Id LD 2XISWO 250µA 250µA Current SW 1:1 Switching current varying circuit Figure 1 Switching Current Setting Equivalent Circuit 1. Switching current initial setting circuit The switching current initial set value is set by switching current setting resistance Rs in a V-I conversion circuit using an op-amp. ISWO [mA] = 30 × Vref (1.5V) [V] RS [kΩ] ............................ (1) 2. Switching current varying circuit If the potential difference between the CH pin voltage and internal reference voltage is designated ∆V (= VCH – 2.5 V), Id flowing in a 2 kΩ resistance due to this ∆V voltage is as follows. Id = ∆V 2kΩ ............................ (2) Therefore, the I1 and I2 currents are given by the following equations. I1 = 250 µA-Id I2 = 250 µA-Id ............................ (3) Next, the relationship between I1, I2, ISW1, and ISW2 due to a Gilbert circuit comprising D1, D2, Q1, and Q2, is given by the following equation. I1 I2 = Isw1 Isw2 ............................ (4) Also, the relationship between ISW1, ISW2, and ISW0 is given by the following equation. Isw1 + Isw2 = 2 • Iswo ............................ (5) Finding ISW2 from Equations (4) and (5), ISW2 = 2 • ISWO × I1 I1 + I2 Rev.1.0, Sep.19.2003, page 16 of 20 ............................ (6) M61880FP Meanwhile, ISW can be expressed as follows. Isw = 2 • Iswo−Isw2 ............................ (7) The relationship between ISW and ∆V is found as shown below. Substituting Equation (6) in Equation (7), ISW = 2 • ISWO ( I2 I1 + I2 ) ............................ (8) and further substituting Equation (3), ISW = ISWO (1+ Id 250µA ) ............................ (9) Next, substituting Equation (2) gives the relationship between ISW and ∆V as follows. ISW = ISWO (1+ ∆V/2kΩ 250µA ) ............................ (10) A characteristic curve of the CH pin voltage and switching current is shown toward the end of “Electrical Characteristic Graphs” following. Rev.1.0, Sep.19.2003, page 17 of 20 M61880FP Electrical Characteristic Graphs Reference Voltage - Temperature Characteristic Thermal Reduction Curve Reference Voltage Vref (V) Power Consumption Pd (mW) VCC=5V 1200 1000 800 600 400 200 1.54 1.52 1.50 1.48 1.46 1.44 0 0 -25 0 25 50 75 -25 100 125 Ambient Temperature Ta (˚C) 0 25 50 75 100 125 Ambient Temperature Ta (˚C) VB Pin Input Voltage - Current Voltage Characteristic Bias Setting Pin Input Voltage Output Characteristic VCC=5V Ta=25˚C 90.0 80.0 60 Input Current (µA) Bias Output Current IB (mA) 100.0 VCC=5V Ta=25˚C RB=51Ω 50 40 30 20 70.0 60.0 50.0 40.0 30.0 20.0 10 10.0 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 1.0 0 Input Voltage (V) VB Pin Input Voltage (V) Switching Current Setting Resistance Current Characteristic VCC=5V Ta=25˚C 60 50 40 30 20 VB=1.5V Switching Current Value ISW (mA) Bias Current Value IB (mA) Bias Current Setting Resistance Current Characteristic 10 2.0 VCC=5V Ta=25˚C 120 100 80 60 40 VCH=2.5V 20 0 0 0 100 200 300 400 Bias Current Setting Resistance Value RB (Ω) Rev.1.0, Sep.19.2003, page 18 of 20 0 1 2 3 4 Switching Current Setting Resistance Value RS (kΩ) M61880FP CH Pin Voltage - Switching Current Characteristic APC Comparator Input Voltage - Offset Voltage Characteristic 10.0 9.0 VCC=5V Ta=25˚C 100 VCC=5V Ta=25˚C 8.0 7.0 80 Voff (mV) Switching Current ISW (mA) 120 60 40 6.0 5.0 4.0 3.0 2.0 20 1.0 RS=820Ω 0 0 1 1.5 2 2.5 3 CH Pin Voltage Vch (V) Rev.1.0, Sep.19.2003, page 19 of 20 3.5 0 1.0 2RM Voltage (V) 2.0 Rev.1.0, Sep.19.2003, page 20 of 20 G Z1 E HE 1 20 EIAJ Package Code SOP20-P-300-1.27 z Detail G e D JEDEC Code − y b x Weight(g) 0.26 M 10 11 F A Detail F A2 Lead Material Cu Alloy L1 MMP c A1 A A1 A2 b c D E e HE L L1 z Z1 x y Symbol e1 b2 e1 I2 b2 Dimension in Millimeters Min Nom Max 2.1 − − 0.2 0.1 0 − 1.8 − 0.5 0.4 0.35 0.25 0.2 0.18 12.7 12.6 12.5 5.4 5.3 5.2 − 1.27 − 8.1 7.8 7.5 0.8 0.6 0.4 − 1.25 − − 0.585 − − − 0.735 − − 0.25 0.1 − − 8˚ 0˚ − − − 0.76 − 7.62 − − 1.27 − Recommended Mount Pad e Plastic 20pin 300mil SOP I2 20P2N-A M61880FP Package Dimensions L Sales Strategic Planning Div. Nippon Bldg., 2-6-2, Ohte-machi, Chiyoda-ku, Tokyo 100-0004, Japan Keep safety first in your circuit designs! 1. Renesas Technology Corp. puts the maximum effort into making semiconductor products better and more reliable, but there is always the possibility that trouble may occur with them. Trouble with semiconductors may lead to personal injury, fire or property damage. Remember to give due consideration to safety when making your circuit designs, with appropriate measures such as (i) placement of substitutive, auxiliary circuits, (ii) use of nonflammable material or (iii) prevention against any malfunction or mishap. Notes regarding these materials 1. These materials are intended as a reference to assist our customers in the selection of the Renesas Technology Corp. product best suited to the customer's application; they do not convey any license under any intellectual property rights, or any other rights, belonging to Renesas Technology Corp. or a third party. 2. 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