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LT1611 Inverting 1.4MHz Switching Regulator in SOT-23
FEATURES
s s s s s s s s s s
DESCRIPTIO
Very Low Noise: 1mVP-P Output Ripple - 5V at 150mA from a 5V Input Better Regulation Than a Charge Pump Effective Output Impedance: 0.14 Uses Tiny Capacitors and Inductors Internally Compensated Fixed Frequency 1.4MHz Operation Low Shutdown Current: <1A Low VCESAT Switch: 300mV at 300mA Tiny 5-Lead SOT-23 Package
The LT(R)1611 is the industry's first inverting 5-lead SOT-23 current mode DC/DC converter. Intended for use in small, low power applications, it operates from an input voltage as low as 1.1V and switches at 1.4MHz, allowing the use of tiny, low cost capacitors and inductors 2mm or less in height. Its small size and high switching frequency enable the complete DC/DC converter function to consume less than 0.25 square inches of PC board area. Capable of generating - 5V at 150mA from a 5V supply or - 5V at 100mA from a 3V supply, the LT1611 replaces nonregulated "charge pump" solutions in many applications. The LT1611 operates in a dual inductor inverting topology which filters the input side as well as the output side of the DC/DC converter. Fixed frequency switching ensures a clean output free from low frequency noise typically present with charge pump solutions. No load quiescent current of the LT1611 is 3mA, while in shutdown quiescent current drops to 0.5A. The 36V switch allows VIN to VOUT differential of up to 33V. The LT1611 is available in the 5-lead SOT-23 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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MR Head Bias Digital Camera CCD Bias LCD Bias GaAs FET Bias Positive-to-Negative Conversion
TYPICAL APPLICATIO
VIN 5V VIN L1A 22H
C2 1F
L1B 22H
D1 SW LT1611 NFB GND R2 10k R1 29.4k 1200pF SHDN C1 22F
+
VOUT -5V 150mA C3 22F
VOUT 20mV/DIV AC COUPLED
LOAD CURRENT C1: AVX TAJB226M010 C2: TAIYO YUDEN LMK212BJ105MG C3: TAIYO YUDEN JMK325BJ226MM (1210 SIZE) D1: MBR0520 L1: SUMIDA CLS62-220 OR 2x MURATA LQH3C220 (UNCOUPLED)
1611 TA01
150mA 50mA 100s/DIV
1611 F10
Figure 1. 5V to - 5V, 150mA Low Noise Inverting DC/DC Converter
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Transient Response
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LT1611
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW SW 1 GND 2 NFB 3 4 SHDN 5 VIN
VIN Voltage .............................................................. 10V SW Voltage ................................................- 0.4V to 36V NFB Voltage ............................................................. - 3V Current into NFB Pin ............................................. 1mA SHDN Voltage .......................................................... 10V Maximum Junction Temperature .......................... 125C Operating Temperature Range Commercial ............................................. 0C to 70C Extended Commercial (Note 2) ........... - 40C to 85C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER LT1611CS5 S5 PART MARKING LTES
S5 PACKAGE 5-LEAD PLASTIC SOT-23
TJMAX = 125C, JA = 256C/W
Consult factory for Industrial and Military grade parts.
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 1.5V, VSHDN = VIN unless otherwise noted.
PARAMETER Minimum Operating Voltage Maximum Operating Voltage NFB Pin Bias Current Feedback Voltage Quiescent Current Quiescent Current in Shutdown Reference Line Regulation Switching Frequency Maximum Duty Cycle Switch Current Limit Switch VCESAT Switch Leakage Current SHDN Input Voltage High SHDN Input Voltage Low SHDN Pin Bias Current VSHDN = 3V VSHDN = 0V 25 0 (Note 3) ISW = 300mA VSW = 5V 1 0.3 50 0.1 VSHDN = 1.5V, Not Switching VSHDN = 0V, VIN = 2V VSHDN = 0V, VIN = 5V 1.5V VIN 10V
q q
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
TYP 0.9
MAX 1.1 10 - 6.7 - 1.255 4.5 0.5 1.0 0.2 1.8
UNITS V V A V mA A A %/V MHz % mA
VNFB = -1.23V
q q
- 2.7 - 1.205
- 4.7 - 1.23 3 0.01 0.01 0.02
1.0 82 550
1.4 86 800 300 0.01
350 1
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: C grade device specifications are guaranteed over the 0C to 70C temperature range. In addition, C grade device specifications are assured over the - 40C to 85C temperature range by design or correlation, but are not production tested.
Note 3: Current limit guaranteed by design and/or correlation to static test. Slope compensation reduces current limit at higher duty cycle.
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WW
W
mV A V V A A
LT1611 TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency, VOUT = - 5V
85 80 75 EFFICIENCY (%) 70 65 60 55 50 0 25 50 75 100 LOAD CURRENT (mA) 125 150
1611 G01
VIN = 5V
-1.235
NFB PIN BIAS CURRENT (A) -25 0 25 50 TEMPERATURE (C) 75 100
1611 G02
VNFB (V)
VIN = 3V
Switch VCESAT vs Switch Current
700 600 500 TA = 25C SHDN PIN BIAS CURRENT (A) 40 50
SWITCH CURRENT LIMIT (mA)
VCESAT (mV)
400 300 200 100 0 0 100 200 300 400 500 SWITCH CURRENT (mA) 600 700
Oscillator Frequency vs Temperature
2.00 1.75 VIN = 5V OPERATING CURRENT (mA) 6.0 5.5
SWITCHING FREQUENCY (MHz)
SWITCH CURRENT LIMIT (mA)
1.50 1.25 1.00 0.75 0.50 0.25 0 -50 VIN = 1.5V
-25
0 25 50 TEMPERATURE (C)
* Includes bias current through R1, R2 and Schottky leakage current at T 75C
UW
1611 G04
VNFB vs Temperature
-1.245 -1.240 6 5 4 3 2 1
NFB Pin Bias Current vs Temperature
-1.230 -1.225 -1.220 -1.215 -1.210 -50
0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
1611 G03
SHDN Pin Bias Current vs VSHDN
900 800 700 600 500 400 300 200 100
Switch Current Limit vs Duty Cycle
TA = 25C
30
20
10
0 0 1 2 3 4 SHDN PIN VOLTAGE (V) 5
1611 G05
0 10 20 30 40 50 60 DUTY CYCLE (%) 70 80
1611 G06
No-Load Operating Quiescent Current vs Temperature*
900 800 700 600 500 400 300 200 100
Switch Current Limit vs Temperature (Duty Cycle = 30%)
5.0 4.5 4.0 3.5 3.0 2.5
75
100
1611 G07
2.0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
1611 G08
0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
1611 G09
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LT1611
PIN FUNCTIONS
SW (Pin 1): Switch Pin. Minimize trace area at this pin to keep EMI down. GND (Pin 2): Ground. Tie directly to local ground plane. NFB (Pin 3): Negative Feedback Pin. Minimize trace area. Reference voltage is -1.23V. Connect resistive divider tap here. The suggested value for R2 is 10k. Set R1 and R2 according to:
1.23 + 4.5 * 10- 6 R2 SHDN (Pin 4): Shutdown Pin. Tie to 1V or more to enable device. Ground to shut the device down. R1 = VOUT - 1.23
BLOCK DIAGRAM
VIN 5 R5 40k
-
Q1 VOUT R1 (EXTERNAL) NFB R2 (EXTERNAL) Q2 x10 R3 30k R4 140k 3 NFB
CC A=3 1.4MHz OSCILLATOR SHDN 4 SHUTDOWN
CPL (OPTIONAL)
Figure 2
OPERATIO
The LT1611 combines a current mode, fixed frequency PWM architecture with a -1.23V reference to directly regulate negative outputs. Operation can be best understood by referring to the block diagram of Figure 2. Q1 and Q2 form a bandgap reference core whose loop is closed around the output of the converter. The driven reference point is the lower end of resistor R4, which normally sits at a voltage of -1.23V. As the load current changes, the NFB pin voltage also changes slightly, driving the output of gm amplifier A1. Switch current is regulated directly on a cycle-to-cycle basis by A1's output. The flip-flop is set at the beginning of each cycle, turning on the switch. When the summation of a signal representing switch current and a ramp generator (introduced to avoid subharmonic oscillations at duty factors greater than 50%) exceeds the VC signal, comparator A2 changes stage, resetting the flip-
flop and turning off the switch. Output voltage decreases (the magnitude increases) as switch current is increased. The output, attenuated by external resistor divider R1 and R2, appears at the NFB pin, closing the overall loop. Frequency compensation is provided internally by RC and CC. Transient response can be optimized by the addition of a phase lead capacitor, CPL, in parallel with R1 in applications where large value or low ESR output capacitors are used. As load current is decreased, the switch turns on for a shorter period each cycle. If the load current is further decreased, the converter will skip cycles to maintain output voltage regulation. The LT1611 can work in either of two topologies. The simpler topology appends a capacitive level shift to a
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RC
RAMP GENERATOR
-
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VIN (Pin 5): Input Supply Pin. Must be locally bypassed.
VIN R6 40k 1 SW COMPARATOR A1 gm FF S DRIVER Q Q3
+
A2
R
+
0.15
-
2 GND
1611 BD
LT1611
OPERATIO
boost converter, generating a negative output voltage, which is directly regulated. The circuit schematic is detailed in Figure 3. Only one inductor is required, and the two diodes can be in a single SOT-23 package. Output noise is the same as in a boost converter, because current is delivered to the output only during the time when the LT1611's internal switch is off. If D2 is replaced by an inductor, as shown in Figure 4, a higher performance solution results. This converter topology was developed by Professor S. Cuk of the California Institute of Technology in the 1970s. A low ripple voltage results with this topology due to inductor L2 in series with the output. Abrupt changes in output capacitor current are eliminated because the output inductor delivers current to the output during both the off-time and the on-time of the LT1611 switch. With proper layout and high quality output capacitors, output ripple can be as low as 1mVP-P. The operation of Cuk's topology is shown in Figures 5 and 6. During the first switching phase, the LT1611's switch, represented by Q1, is on. There are two current loops in operation. The first loop begins at input capacitor C1, flows through L1, Q1 and back to C1. The second loop flows from output capacitor C3, through L2, C2, Q1 and back to C3. The output current from RLOAD is supplied by L2 and C3. The voltage at node SW is VCESAT and at node SWX the voltage is -(VIN + |VOUT|). Q1 must conduct both L1 and L2 current. C2 functions as a voltage level shifter, with an approximately constant voltage of (VIN + |VOUT|) across it.
C2 1F D2
VIN
+
C1
SHUTDOWN
GND
R2 10k
GND
R2 10k
1611 F03
Figure 3. Direct Regulation of Negative Output Using Boost Converter with Charge Pump
Figure 4. L2 Replaces D2 to Make Low Output Ripple Inverting Topology. Coupled or Uncoupled Inductors Can Be Used. Follow Phasing If Coupled for Best Results
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When Q1 turns off during the second phase of switching, the SW node voltage abruptly increases to (VIN + |VOUT|). The SWX node voltage increases to VD (about 350mV). Now current in the first loop, begining at C1, flows through L1, C2, D1 and back to C1. Current in the second loop flows from C3 through L2, D1 and back to C3. Load current continues to be supplied by L2 and C3. An important layout issue arises due to the chopped nature of the currents flowing in Q1 and D1. If they are both tied directly to the ground plane before being combined, switching noise will be introduced into the ground plane. It is almost impossible to get rid of this noise, once present in the ground plane. The solution is to tie D1's cathode to the ground pin of the LT1611 before the combined currents are dumped into the ground plane as drawn in Figures 4, 5 and 6. This single layout technique can virtually eliminate high frequency "spike" noise so often present on switching regulator outputs. Output ripple voltage appears as a triangular waveform riding on VOUT. Ripple magnitude equals the ripple current of L2 multiplied by the equivalent series resistance (ESR) of output capacitor C3. Increasing the inductance of L1 and L2 lowers the ripple current, which leads to lower output voltage ripple. Decreasing the ESR of C3, by using ceramic or other low ESR type capacitors, lowers output ripple voltage. Output ripple voltage can be reduced to arbitrarily low levels by using large value inductors and low ESR, high value capacitors.
L1 L1 VIN D1 VIN LT1611 SHDN NFB SW -VOUT R1 C3 C2 1F L2
+
C1
D1 VIN LT1611 NFB SW -VOUT R1 C3
1611 F04
5
LT1611
OPERATIO
VIN
+
C1
Figure 5. Switch-On Phase of Inverting Converter. L1 and L2 Current Have Positive dI/dt
VIN + VOUT+ VD L1 VIN SW C2
VD SWX L2 -VOUT
+
C1
Q1
D1 C3 RLOAD
Figure 6. Switch-Off Phase of Inverting Converter. L1 and L2 Current Have Negative dI/dt
Transient Response The inverting architecture of the LT1611 can generate a very low ripple output voltage. Recently available high value ceramic capacitors can be used successfully in LT1611 designs with the addition of a phase lead capacitor, CPL (see Figure 7). Connected in parallel with feedback resistor R1, this capacitor reduces both output perturba-
tions due to load steps and output ripple voltage to very low levels. To illustrate, Figure 7 shows an LT1611 inverting converter with resistor loads RL1 and RL2. RL1 is connected across the output, while RL2 is switched in externally via a pulse generator. Output voltage waveforms are pictured in subsequent figures, illustrating the performance of output capacitor type and the effect of CPL connected across R1.
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VCESAT L1 SW -(VIN + VOUT) C2 SWX L2 -VOUT Q1 D1 C3 RLOAD
1611 F05 1611 F06
LT1611
OPERATIO
VIN 5V VIN L1A 22H
+
C1
SHDN LT1611 NFB GND R2 10k R1 CPL C3 RL1 100
C1: AVX TAJB226M010 C2: TAIYO YUDEN LMK212BJ105MG C3: SEE TEXT D1: MBR0520 L1A, L1B: SUMIDA CLS62-220
Figure 7. Switching RL2 Provides 50mA to 150mA Load Step for LT1611 5V to - 5V Converter
VOUT 50mV/DIV AC COUPLED
LOAD CURRENT
150mA 50mA 100s/DIV
1611 F08
Figure 8. Load Step Response of LT1611 with 22F Tantalum Output Capacitor
VOUT 10mV/DIV
SWITCH VOLTAGE 5V/DIV LOAD = 150mA 200ns/DIV
Figure 10. 22F "B" Case Tantalum Capacitor (AVX TAJ "B" Series) Has ESR Resulting in 20mVP-P Voltage Ripple at Output
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C2 1F L1B 22H D1 SW -VOUT RL2 50
1611 F07
Figure 8 shows the output voltage with a 50mA to 150mA load step, using an AVX TAJ "B" case 22F tantalum capacitor at the output. Output perturbation is approximately 100mV as the load changes from 50mA to 150mA. Steady-state ripple voltage is 20mVP-P, due to L1's ripple current and C3's ESR. Step response can be improved by adding a 3.3nF capacitor (CPL) as shown in Figure 9. Settling time improves from 150s to 40s, although steady-state ripple voltage does not improve. Figure 10 pictures the output voltage and switch pin voltage at 200ns per division. Note the absence of high frequency spikes at the output. This is easily repeatable with proper layout, described in the next section.
VOUT 20mV/DIV AC COUPLED
LOAD CURRENT
150mA 50mA 20s/DIV
1611 F09
Figure 9. Addition of CPL to Figure 7's Circuit Improves Load Step Response. CPL = 3.3nF
1611 F10
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LT1611
OPERATIO
In Figure 11 (also shown on the first page), output capacitor C3 is replaced by a ceramic unit. These large value ceramic capacitors have ESR of about 2m and result in very low output ripple. At the 20mV/division scale, output voltage ripple cannot be seen. Figure 12 pictures the output and switch nodes at 200ns per division. The output voltage ripple is approximately 1mVP-P. Again, good layout is mandatory to achieve this level of performance.
VOUT 20mV/DIV AC COUPLED SWITCH VOLTAGE 5V/DIV
150mA LOAD CURRENT 50mA 100s/DIV
1611 F11
Figure 11. Replacing C3 with 22F Ceramic Capacitor (Taiyo Yuden JMK325BJ226MM) Improves Output Noise. CPL = 1200pF Results in Best Phase Margin
GND
Figure 13. Suggested Component Placement. Note Cut in Ground Copper at D1's Cathode
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Layout The LT1611 switches current at high speed, mandating careful attention to layout for best performance. You will not get advertised performance with careless layout. Figure 13 shows recommended component placement. Follow this closely in your printed circuit layout. The cut ground copper at D1's cathode is essential to obtain the low noise achieved in Figures 11 and 12's oscillographs. Input bypass capacitor C1 should be placed close to the LT1611 as shown. The load should connect directly to output capacitor C2 for best load regulation. You can tie the local ground into the system ground plane at C3's ground terminal.
VOUT 5mV/DIV AC COUPLED LOAD = 150mA 200ns/DIV
1611 F12
Figure 12. 22F Ceramic Capacitor at Output Reduces Ripple to 1mVP-P. Proper Layout Is Essential to Achieve Low Noise
L1B -VOUT D1 C3 C2
L1A C1
+
VIN
1 2 3
5
4
SHUTDOWN
R2 R1
1611 F13
LT1611
OPERATIO
Start-Up/Soft-Start The LT1611, starting from VOUT = 0V, reaches final voltage in approximately 450s after SHDN is pulled high, with COUT = 22F, VIN = 5V and VOUT = - 5V. Charging the output capacitor at this speed requires an inrush current of over 1A. If a longer start-up time is acceptable, a soft-start circuit consisting of RSS and CSS, as shown in Figure 14, can be used to limit inrush current to a lower value. Figure 15 pictures VOUT and input current, starting into a 33 load, with RSS of 33k and CSS of 33nF. Input current,
CURRENT PROBE VIN 5V L1A 22H
VOUT 2V/DIV
IIN 200mA/DIV VS 5V/DIV LOAD = 150mA 500s/DIV
1611 F15
Figure 15. RSS = 33k, CSS = 33nF; VOUT Reaches - 5V in 750s; Input Current Peaks at 450mA
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measured at VIN, is limited to a peak value of 450mA as the time required to reach final value increases to 700s. In Figure 16, CSS is increased to 0.1F, resulting in a lower peak input current of 240mA with a VOUT ramp time of 2.1ms. CSS can be increased further for an even slower ramp, if desired. Diode D2 serves to quickly discharge CSS when VSS is driven low to shut down the device. D2 can be omitted, resulting in a "soft-stop" slow discharge of the output capacitor.
C2 1F L1B 22H
+
RSS 33k VSS D2 1N4148 CSS 33nF/0.1F VOUT
D1 C1 22F VIN LT1611 SHDN GND NFB R2 10k SW R1 29.4k CP 1200pF VOUT -5V C3 22F
C1: AVX TAJB226M010 C2: TAIYO YUDEN LMK212BJ105MG C3: TAIYO YUDEN JMK325BJ226MM (1210 SIZE) D1: MBR0520 L1: SUMIDA CLS62-220 OR 2x MURATA LQH3C220 (UNCOUPLED)
1611 F14
Figure 14. RSS and CSS at SHDN Pin Provide Soft-Start to LT1611 Inverting Converter
VOUT 2V/DIV
IIN 200mA/DIV VS 5V/DIV LOAD = 150mA 500s/DIV
1611 F16
Figure 16. RSS = 33k, CSS = 0.1F; VOUT Reaches - 5V in 2.1ms; Input Current Peaks at 240mA
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LT1611
OPERATIO
Output Current
The LT1611 will deliver 150mA at - 5V from a 5V 10% input supply. If a higher voltage supply is available, more output current can be obtained. Figure 17's schematic shows how to get more current. Although the LT1611's maximum voltage allowed at VIN is 10V, the SW pin can handle higher voltage (up to 36V). In Figure 17, the VIN pin of the LT1611 is driven from a 5V supply, while input inductor L1A is driven from a separate 12V supply. Figure 18's graph shows maximum recommended output current as the voltage on L1A is varied. Up to 300mA can be delivered when driving L1A from a 12V supply.
D1 VIN SHDN C1 1F LT1611 NFB GND 10k 29.4k 1200pF SW
VOUT -5V UP TO 300mA C3 22F
MAXIMUM RECOMMENDED OUTPUT CURRENT (mA)
5V
C1, C2: TAIYO YUDEN LMK212BJ105MG C3: TAIYO YUDEN JMK325BJ226MM D1: MBR0520 L1A, L1B: SUMIDA CLS62-220
Figure 17. Increase Output Current By Driving L1A from a Higher Voltage
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COMPONENT SELECTION Inductors Each of the two inductors used with the LT1611 should have a saturation current rating (where inductance is approximately 70% of zero current inductance) of approximately 0.25A or greater. If the device is used in "charge pump" mode, where there is only one inductor, then its rating should be 0.5A or greater. DCR of the inductors should be 0.5 or less. A value of 22H is suitable if using a coupled inductor such as Sumida CLS62-220 or Coiltronics CTX20-1. If using two separate inductors, increasing the value to 47H will result in the same ripple current. Inductance can be reduced if operating from a supply voltage below 3V. Table 1 lists several inductors that will work with the LT1611, although this is not an exhaustive list. There are many magnetics vendors whose components are suitable.
VL (SEE TEXT) L1A 22H
350
C2 1F
L1B 22H
300
250
200
150
100
1611 F17
3
4
5
6
7 8 VL (V)
9
10
11
12
1611 F18
Figure 18. Output Current Increases to 300mA When Driving VL from 12V Supply
LT1611
OPERATIO
Capacitors
As described previously, ceramic capacitors can be used with the LT1611 provided loop stability is considered. For lower cost applications, small tantalum units can be used. A value of 22F is acceptable, although larger capacitance values can be used. ESR is the most important parameter in selecting an output capacitor. The "flying" capacitor (C2 in the schematic figures) should be a 1F ceramic type. An X5R or X7R dielectric should be used to avoid capacitance decreasing severely with applied voltage. The input bypass capacitor is less critical, and either tantalum or
Table 1. Inductor Vendors
VENDOR Sumida Murata Coiltronics PHONE (847) 956-0666 (404) 436-1300 (407) 241-7876 URL www.sumida.com www.murata.com
Table 2. Capacitor Vendors
VENDOR Taiyo Yuden AVX Murata PHONE (408) 573-4150 (803) 448-9411 (404) 436-1300 URL www.t-yuden.com www.avxcorp.com www.murata.com PART Ceramic Caps Ceramic Caps Tantalum Caps Ceramic Caps COMMENT X5R Dielectric
TYPICAL APPLICATIO S
"Charge Pump" Inverting DC/DC Converter
L1 10H 3.3V D1 VIN SHDN C1 1F LT1611 NFB GND 10k 29.4k C3 22F SW D2 -5V 70mA C2 1F
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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ceramic can be used with little trade-off in circuit performance. Some capacitor types appropriate for use with the LT1611 are listed in Table 2. Diodes A Schottky diode is recommended for use with the LT1611. The Motorola MBR0520 is a very good choice. Where the input to output voltage differential exceeds 20V, use the MBR0530 ( a 30V diode). If cost is more important than efficiency, a 1N4148 can be used, but only at low current loads.
PART CLS62-22022 CD43-470 LQH3C-220 CTX20-1 COMMENT 22H Coupled 47H 22H, 2mm Height 20H Coupled, Low DCR www.coiltronics.com
C1, C2: TAIYO YUDEN LMK212BJ105MG C3: TAIYO YUDEN JMK325BJ226MM D1, D2: MBR0520 L1: MURATA LQH3C-100
1611 TA02
11
LT1611
TYPICAL APPLICATIO S
4-Cell to -10V Inverting Converter
L1A 15H VIN C2 1F L1B 15H
C1 22F
EFFICIENCY (%)
+
VIN LT1611 SHDN GND
SW 68.1k NFB 10k VOUT -10V/60mA C3 6.8F
SHUTDOWN
C1: AVX TAJB226M010 (803) 946-0362 C2: TAIYO YUDEN LMK212BJ105MG C3: AVX TAJA685M016 D1: MOTOROLA MBR0520 (800) 441-2447 L1: SUMIDA CL562-150 (847) 956-0666
PACKAGE DESCRIPTION
2.60 - 3.00 (0.102 - 0.118) 1.50 - 1.75 (0.059 - 0.069)
Dimensions in inches (millimeters) unless otherwise noted. S5 Package 5-Lead Plastic SOT-23
(LTC DWG # 05-08-1633)
2.80 - 3.00 (0.110 - 0.118) (NOTE 3)
0.00 - 0.15 (0.00 - 0.006)
0.35 - 0.55 (0.014 - 0.022)
0.09 - 0.20 (0.004 - 0.008) (NOTE 2)
0.35 - 0.50 0.90 - 1.30 (0.014 - 0.020) (0.035 - 0.051) FIVE PLACES (NOTE 2)
NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DIMENSIONS ARE INCLUSIVE OF PLATING 3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 4. MOLD FLASH SHALL NOT EXCEED 0.254mm 5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ)
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Burst Mode is a trademark of Linear Technology Corporation.
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
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4-Cell to -10V Inverting Converter Efficiency
85 80
VIN = 6.5V VIN = 5V
D1
75 70 65 60 55
1611 TA03
VIN = 3.6V
50 0 25 50 75 100 LOAD CURRENT (mA) 125 150
1611 TA04
0.90 - 1.45 (0.035 - 0.057)
1.90 (0.074) REF
0.95 (0.037) REF
S5 SOT-23 0599
COMMENTS 3.3V/75mA from 1V, 600kHz Fixed Frequency 1.5V Minimum VIN, Precise Control of Peak Switch Current 3.3V/200mA from Two Cells, 600kHz Fixed Frequency 42V, 6A/3A Internal Switch, Negative Feedback Regulation 3V/30mA from 1V, 1.7MHz Fixed Frequency, 30A IQ 5V at 200mA from 3.3V Input - 5V at 200mA from 5V Input in MSOP 20A Quiescent Current, VOUT Up to 34V VOUT Up to -34V, 20A Quiescent Current
1611f LT/TP 0999 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1998

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