LTC1142HV Linear Technology Corporation, LTC1142HV Datasheet
LTC1142HV
Available stocks
Related parts for LTC1142HV
LTC1142HV Summary of contents
Page 1
... LTC1142/LTC1142L/LTC1142HV Synchronous Step-Down DESCRIPTIO ® The LTC 1142/LTC1142L/LTC1142HV are dual synchro- nous step-down switching regulator controllers featuring automatic Burst Mode cies at low output currents. The devices are composed of two separate regulator blocks, each driving a pair of external complementary power MOSFETs, at switching frequencies up to 250kHz, using a constant off-time current mode archi- tecture providing constant ripple current in the inductor ...
Page 2
... LTC1142/LTC1142L/LTC1142HV ABSOLUTE AXI U RATI GS Input Supply Voltage (Pins 10, 24) LTC1142, LTC1142L-ADJ ..................... 16V to – 0.3V LTC1142HV, LTC1142HV-ADJ ............. 20V to – 0.3V Continuous Output Current (Pins 6, 9, 20, 23) .... 50mA Sense Voltages (Pins 1, 14, 15, 28) V > 13V .............................................. 13V to – 0. < 13V .................................. ( PACKAGE/ORDER I FOR ATIO TOP VIEW – ...
Page 3
... OUT 0V < V < 8V 16V SHDN 10 24 – Regulation OUT SENSE OUT OUT C = 390pF 700mA T LOAD C = 3000pF (Pins 6, 9, 20, 23 CONDITIONS LTC1142HV-ADJ Only LTC1142HV-ADJ Only LTC1142, LTC1142HV I = 700mA LOAD 700mA LOAD 10 LTC1142 4V < < 12V < V < 12V, 6V < V < 12V 2.1V, 4V < < 12V ...
Page 4
... LOAD Note 4: In applications where R time increases approximately 40%. and power Note 5: The LTC1142/LTC1142L/LTC1142HV are guaranteed to meet A specified performance from and are designed, characterized and expected to meet these extended temperature limits, but are not tested at – and 85 C. Guaranteed I-grade parts are available, consult the factory ...
Page 5
... SHDN3 (Pin 2): When grounded, the 3.3V section oper- ates normally. Pulling Pin 2 high holds both MOSFETs off and puts the 3.3V section in micropower shutdown mode. Requires CMOS logic-level signal with t “float” Pin 2. LTC1142/LTC1142L/LTC1142HV Supply Current in Shutdown 20 PER REGULATOR BLOCK 18 PINS 10, 24 ...
Page 6
... Connects to internal resistive divider which sets the output voltage for the 3.3V section. Pin 28 is also the (–) input for the current comparator on the 3.3V section. LTC1142HV-ADJ/LTC1142L-ADJ + SENSE 1 (Pin 1): The (+) Input to the Section 1 Current Comparator. A built-in offset between Pins 1 and 28 in conjunction with R for this section ...
Page 7
... Requires CMOS logic signal with Pin 17. LTC1142/LTC1142L/LTC1142HV SGND2 (Pin 18): The section 2 small-signal ground must be routed separately from other grounds to the (–) termi- nal of the section 2 output capacitor. PGND2 (Pin 19): The section 2 driver power ground connects to source of the N-channel MOSFET and the (– ...
Page 8
... LTC1142/LTC1142L/LTC1142HV CTIO AL DIAGRA Only one regulator block shown. Pin numbers are for 3.3V (5V) sections for LTC1142/LTC1142HV, and for LTC1142L-ADJ/LTC1142HV-ADJ. OUT1 OUT2 PIN NUMBERS FOR 2(16) LTC1142, LTC1142HV LTC1142-ADJ PIN NUMBERS 3(17) FOR LTC1142L-ADJ LTC1142HV-ADJ SLEEP + S – TH1 TH2 25(11 OPERATIO Refer to Functional Diagram ...
Page 9
... Since the OUT 3.3V and 5V sections in the LTC1142 are identical and similarly section 1 and section 2 in the LTC1142HV-ADJ/ LTC1142L-ADJ are identical, the process of component selection is the same for both sections. The circuit shown in Figure 1 can be configured for operation input voltage of 20V ...
Page 10
... LTC1142/LTC1142L/LTC1142HV U U APPLICATIO S I FOR ATIO both track I . Once R has been chosen, I MAX SENSE I can be predicted from the following: SC(PK) 15mV I BURST R SENSE 150mV I = SC(PK) R SENSE The LTC1142 automatically extends t circuit to allow sufficient time for the inductor current to decay between switch cycles. The resulting ripple current ...
Page 11
... N-channel MOSFET for the synchronous switch. The main selection criteria for the power MOSFETs are the threshold voltage V and on- resistance R GS(TH) Kool registered trademark of Magnetics, Inc. LTC1142/LTC1142L/LTC1142HV W U The minimum input voltage determines whether standard threshold or logic-level threshold MOSFETs must be used. For V (V < ...
Page 12
... LTC1142/LTC1142L/LTC1142HV U U APPLICATIO S I FOR ATIO dead-time, which could cost as much efficiency (although there are no other harmful effects if D1 and D2 are omitted). Therefore, D1 and D2 should be selected for a forward voltage of less than 0.6V when conducting I C and C Selection IN OUT In continuous mode, the source current of the P-channel ...
Page 13
... I R losses 1. The DC supply current is the current which flows into V (pin 24 for the 3.3V section, Pin 10 for the 5V IN LTC1142/LTC1142L/LTC1142HV W U shifts by an section) less the gate charge current. For V OUT LTC1142 DC supply current for each section is 160 A with no load, and increases proportionally with load up also begins to charge to a constant 1 ...
Page 14
... A similar calculation for the 3.3V section results in the , C and L can SENSE T component values shown in Figure 14. LTC1142HV-ADJ/LTC1142L-ADJ Adjustable Applications When an output voltage other than 3. required, the LTC1142 adjustable version is used with an external resistive divider from V lated output voltage is determined by: V OUT = 0.007(63 – ...
Page 15
... U U APPLICATIO S I FOR ATIO To prevent stray pickup a 100pF capacitor is suggested across R1 located close to the LTC1142HV-ADJ/LTC1142L- ADJ as in Figure 6. The external divider network must be placed across C with the negative plate of C OUT to signal ground. Refer to the Board Layout Checklist [PIN 2(16)] ...
Page 16
... LTC1142/LTC1142L/LTC1142HV U U APPLICATIO S I FOR ATIO ing with Kelvin connections. Be sure to use a PCB pattern similar to that shown in Figure 7 for the current sense resistors. 4. Does the (+) plate of C connect to the source of the IN P-channel MOSFET as closely as possible? This capaci- tor provides the AC current to the P-channel MOSFET. ...
Page 17
... R1 52.3k 100pF DALE WSL-2010-.05 SENSE1, SENSE2 L1: SUMIDA CDRH125-270 L2: SUMIDA CDRH125-330 Figure 11. LTC1142HV-ADJ Dual Regulator with 3.6V/2A and 5V/2A Outputs LTC1142/LTC1142L/LTC1142HV W U With the addition current is generated through R1 causing an offset of: V OFFSET If V OFFSET Burst Mode operation is prevented from occurring. Since > 5A) ...
Page 18
... C OUT1 220 F 10V D1 N- MBRS130T3 Si9410DY 49. 49.9k 100pF IRC L1206-01-R075-J SENSE1 R : IRC L1206-01-R050-J SENSE2 Figure 12. LTC1142HV-ADJ High Efficiency Regulator with 3.3V/2A and 2.5V/1.5A Outputs C + IN3 22 F 0.22 F 25V 2 P-CH Si9433DY L1 R SENSE3 0.033 OUT3 3.3V/3A 1000pF D1 MBRS130T3 N- OUT3 Si9410DY ...
Page 19
... SENSE2 L1: COILTRONICS CTX50-4 L2: COILTRONICS CTX25-4 Figure 15. LTC1142HV-ADJ High Efficiency Power Supply Providing 3.3V/2A with Built-In Battery Charger 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
Page 20
... LTC1142/LTC1142L/LTC1142HV U TYPICAL APPLICATIO S Figure 16. LTC1142HV-ADJ Output Current vs Trickle Charge Set Resistance (R ) for the Circuit in Figure 15 Using a 0.1 Current Sense Resistor R X PACKAGE DESCRIPTIO 5.20 – 5.38** (0.205 – 0.212) 0 – 8 0.13 – 0.22 0.55 – 0.95 (0.005 – 0.009) (0.022 – 0.037) ...