SH1605 FAIRCHILD | Alldatasheet

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A Schlumberger Company . . Switching Regulator Hybrid Products sss Description Connection Diagram The SH1605 is a hybrid switching regulator with high 8-Pin TO-3 Type output current capabilities. It incorporates a ERROR temperature-compensated voltage reference, a duty- AMPLIFIER cycle controllable oscillator, error amplifier, high Vaer INPUT current-high voltage output switch, and a power diode. GNO- NS ron The SH1605 can supply 5 A of regulated output = = current over a wide range of output voltage. 7 ys i; § ©©o 7 = STEP DOWN SWITCHING REGULATOR ! © \\ = OUTPUT ADJUSTABLE FROM 3.0 TO 30 V O01 @s! O 3 = 5 A OUTPUT CURRENT \\Pwo@r) = HIGH EFFICIENCY 7 wae @ UP TO 150 W OUTPUT POWER oer == INPUT STEERING NC Absolute Maximum Ratings T, = 25°C unless DIODE (ANODE) otherwise specified Vin - Vourimin) 5V Case = Ground Input Voltage 35 V Max Output Current 6A Order Information Operating Temperature Ty 150°C Internal Power Dissipation 20 W Type Package Code Part No. Storage Temperature Range ~65°C to +150°C SH1605 Metal 8G SH1605S Duty Cycle 20 =D = 80% Vz8 60V Ing 6A Block Diagram a 1, 1 _ | ! 4 T | I l | l | I I | | | | | [ ) > ] | CASE | | I I 4 I ! I 4 1 ! 3 [ee] = | | I ! I I , 327

ee] Electrical Characteristics Tc = 25°C, Vin = 15 V unless otherwise specified. symbol |Characterstce leonaons a 55 [as — um Vout _| Output Voltage Vin= Vot5V,lo=2A [so [| _—i[soo fv ‘7 lout = 5.0 A, v Vs Switch Saturation our = 2.0A y - lout = 5.0 A, Vv Ve Diode On Voltage our = 20A Vv ino Diode Reverse Current Vrp = 25 V rr Ee ee lo Quiescent Current lout = 0.2 A [so | [ma Reference and Oscillator Section Switching Characteristics Symbol [Characteristics [Conditions Min. [Typ [Max [Units . lout = 2.0A 700 ns tr Voltage Rise Time iour = 5.0A 18 hs lout = 2.0A 700 ns tr Voltage Fall Time our = 5.0A 900 te Thermal Characteristics . ceinati lout = 5.0 A Pp Power Dissipation Vour = i0V w Vout = 10V, Notes 1. f¢-a. Typical is 30°C/W for natural convection cooling. 2. For heatsinking requirements see power derating curve. SS 3-28

Power Derating Curve Design Equations * LI Pout X 100 : im Efficiency (n) = “py COCOONS 5 -{ \\ ton ett TOT ATTT T Y Transistor DC Losses (Pr) = lout X Vs Tou + tOee scot a ton + torr Pere tore fe N Diode DC Losses (Pp) = lour X VF toy + torr Poe TNS V2 ton PP rT TyTN] Drive Circuit Losses (DL) = 309 X ion + torr ttl t Tt rity CS CASE TEMPERATURE —“c Switching Losses Transistor: tet ty (Ps) = Vin X lout Bion + tore) . ton Vout Transistor Duty Cycle = Toy toRF = VIN” - torr Vout Diode Duty Cycle = toy 4 torr = 1~ Vy Power Inductor (PL) = lout? X Ri (Winding Resistance) Efficiency: Vout lout () = Vourlout + Pr + Pp + DL + Ps # Py X 100 Denna 329

Design Considerations The output capacitor can now be determined Figure 1 is a typical design of a step-down switching as follows: regulator using the SH1605. Ay c = Bic Vaan Nominal Design Objectives O¢mind * Kein) Vripptevmax)) Vout = +5 V Line Regulation = 2% re ee loutimax) = 5.0 A Load Regulation = 2% = (x77 10) (1X 10") loutimin) = 1.0 A Ripple (max) = 0.1 Vpk-pk Vin = 12 to 18V Efficiency = 70% = 325 uF First, R3 is calculated trom Equation 5: The maximum acceptable ESR is therefore Vrippl (2 109(Vout — 2.5) EsR(max) = BEL _ 4 o250 R3= p52 ‘(max) Normally, the minimum capacitance value should be Since the required lout(min) is 1A to maintain increased considerably if a low ESR capacitor continouous operation, the peak-to-peak current is not used. excursion must be equal to 2 A or less, i.e., As a final step for minimizing switching transients at Aly = 2 loutmin) the device input, a low ESR capacitor must be used for decoupling purposes between the input terminal To calculate the value of the inductor, assume the and ground. nominal on time of the system as 60 us. This value is chosen keeping the efficiency /component-size trade- The SH1605 is a highly versatile building block for off in mind. From Equation 1. high current, step-down switching regulator systems. Vin = Vour 5 However, to attain optimum performance and reliability IN 40 7 the following guidelines should be followed: lia ( an Vso = 2 (6X 10°) = 3004H Keep operating period long, relative to the device switching times, for optimum efficiency. where Vin(nom) = 15 V, ton = 60 us ™ Insure that the inductor stays out of saturation and . minimize the series resistance Aly=2A ™ Use high quality capacitors for input and output to ‘ . minimize ripple and noise. One very important element in achieving the optimum performance in a switching regulator is to insure the inductor is kept below the specified saturation limits. Fig. 1 Design Example 300 Ht Since the timing capacitor controls the 60 us on time, 5 8 Cry can be determined using Equation 7: bm (tond(lc) (6 x 1075)(2.5 x 1075) ones fon 1 + [2s ue 2 Vy Cr= ay = Bx 107" = 3000 pF Vw CASE 1000 a where Ic = 25 uA nominal per data sheet. | 9003 wr ‘ | | Taek Y The final step is to determine the requirements for the — output capacitor Co to obtain the desired value of a ripple voltage. Consideration must be given to the = absolute value of Co as well as the internal effective Note series resistance (ESR). Since the capacitor size is Circuit Performance inversely proportional to the operating frequency, the Vin = 12-18 V lowest frequency of operation must be calculated. Vour = 5.06 V Minimum operating frequency can be determined by Load Reg. = 50 mV (1 A =< Ioyt S 5A) using Aly(max) VS Ali(nom) in Equation 9. Line Reg. = 50 mV (12 V < Vin 18 V)

1 SH1605 must be mounted on a heat sink with a maximum thermal

Minimum Frequency = +5 qgua = 7-7 kHz resistance of ga = 4° C/W. TS 3-30