LT1934 LINER [Linear Technology], LT1934 Datasheet

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LT1934

Manufacturer Part Number
LT1934
Description
Micropower Step-Down Switching Regulators in ThinSOT
Manufacturer
LINER [Linear Technology]
Datasheet

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FEATURES
TYPICAL APPLICATIO
APPLICATIO S
4.5V TO 34V
Wide Input Voltage Range: 3.2V to 34V
Micropower Operation: I
5V at 250mA from 6.5V to 34V Input (LT1934)
5V at 60mA from 6.5V to 34V Input (LT1934-1)
3.3V at 250mA from 4.5V to 34V Input (LT1934)
3.3V at 60mA from 4.5V to 34V Input (LT1934-1)
Low Shutdown Current: <1 A
Low V
Low Profile (1mm) SOT-23 (ThinSOT
Wall Transformer Regulation
Automotive Battery Regulation
Standby Power for Portable Products
Distributed Supply Regulation
Industrial Control Supplies
ON OFF
V
IN
2.2 F
CESAT
C2
C1: SANYO 4TPB100M
C2: TAIYO YUDEN GMK325BJ225MN
D1: ON SEMICONDUCTOR MBR0540
D2: CENTRAL CMDSH-3
L1: SUMIDA CDRH4D28-470
Switch: 200mV at 300mA
3.3V Step-Down Converter
V
SHDN
U
IN
LT1934
BOOST
GND
SW
FB
Q
= 12 A
U
D1
0.22 F
10pF
TM
47 H
) Package
D2
L1
1M
604k
+
1934 TA01
C1
100 F
V
3.3V
250mA
OUT
DESCRIPTIO
The LT
verter with internal 400mA power switch, packaged in a
low profile (1mm) ThinSOT. With its wide input range of
3.2V to 34V, the LT1934 can regulate a wide variety of
power sources, from 4-cell alkaline batteries and 5V logic
rails to unregulated wall transformers and lead-acid bat-
teries. Quiescent current is just 12 A and a zero current
shutdown mode disconnects the load from the input
source, simplifying power management in battery-pow-
ered systems. Burst Mode
internal power switch result in high efficiency over a broad
range of load current.
The LT1934 provides up to 300mA of output current. The
LT1934-1 has a lower current limit, allowing optimum
choice of external components when the required output
current is less than 60mA. Fast current limiting protects
the LT1934 and external components against shorted
outputs, even at 34V input.
Burst Mode is a registered trademark of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Micropower Step-Down
®
1934 is a micropower step-down DC/DC con-
100
90
80
70
60
50
Switching Regulators
0.1
LT1934
V
IN
= 12V
U
1
LOAD CURRENT (mA)
Efficiency
V
V
LT1934/LT1934-1
OUT
®
OUT
operation and the low drop
10
= 3.3V
= 5V
in ThinSOT
100
1934 TA02
1
1934f

Related parts for LT1934

LT1934 Summary of contents

Page 1

... DC/DC con- verter with internal 400mA power switch, packaged in a low profile (1mm) ThinSOT. With its wide input range of 3.2V to 34V, the LT1934 can regulate a wide variety of power sources, from 4-cell alkaline batteries and 5V logic rails to unregulated wall transformers and lead-acid bat- teries ...

Page 2

... BOOST Pin Voltage ................................................. 40V BOOST Pin Above SW Pin ...................................... 20V SHDN Pin ............................................................... 34V FB Voltage ................................................................ 6V SW Voltage ............................................................... V Operating Temperature Range (Note 2) .......................... LT1934E/LT1934E-1 ......................... – LT1934I/LT1934I-1 ......................... – 125 C Maximum Junction Temperature .......................... 125 C Storage Temperature Range ................. – 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS ...

Page 3

... Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: The LT1934E and LT1934E-1 are guaranteed to meet performance specifications from Specifications over the – operating temperature range are assured by design, characterization and ...

Page 4

... SHDN PIN VOLTAGE (V) 1934 G08 Undervoltage Lockout vs Temperature – 100 125 TEMPERATURE ( C) 1934 G11 Minimum Input Voltage OUT LT1934 OUT BOOST DIODE TIED TO OUTPUT V TO START RUN 100 LOAD CURRENT (mA) 1934 G13 ...

Page 5

... SHDN V ON OFF 4 REF GND 2 SHDN (Pin 4): The SHDN pin is used to put the LT1934 in shutdown mode. Tie to ground to shut down the LT1934. Apply 2.3V or more for normal operation. If the shutdown feature is not used, tie this pin to the V V (Pin 5): The V IN internal regulator and to the internal power switch. This pin must be locally bypassed ...

Page 6

... Page Schematic) 6 the flip-flop when this current reaches 400mA (120mA for the LT1934-1). After the 1.8 s delay of the off-time one-shot, the cycle repeats. Generally, the LT1934 will reach current limit on every cycle—the off time is fixed and the on time is regulated so that the LT1934 operates at the correct duty cycle. The 1.8 s off time is lengthened when the FB pin voltage falls below 0.8V ...

Page 7

... The lower peak switch current allows the use of smaller components (input capacitor, inductor and output capacitor). The ripple current at the input of the LT1934-1 circuit will be smaller and may be an important consideration if the input supply is current limited or has high impedance. The LT1934-1’s current draw during faults (output overload or short) and start-up is lower ...

Page 8

... The input capacitor is required to reduce the resulting voltage ripple at the LT1934 and to force this switching current into a tight local loop, minimizing EMI. The input capacitor must have low impedance at the switching frequency to do this effectively ...

Page 9

... OUT LIM OUT For example, an LT1934 producing 3.3V with requires 33 F. This value can be relaxed if small circuit size is more important than low output ripple. Sanyo’s POSCAP series in B-case and C-case sizes pro- vides very good performance in a small package for the LT1934 ...

Page 10

... For proper start- up, the minimum input voltage is also limited by the boost circuit. If the input voltage is ramped slowly, or the LT1934 is turned on with its SHDN pin when the output is already in regulation, then the boost capacitor may not be fully charged ...

Page 11

... OUT 1M D4: MBR0530 Figure 4. Diode D4 Prevents a Shorted Input from Discharging a Backup Battery Tied to the Output; It Also Protects the Circuit from a Reversed Input. The LT1934 Runs Only When the Input is Present PCB Layout 100 For proper operation and minimum EMI, care must be 1934 G13 taken during printed circuit board layout ...

Page 12

... SW and BOOST nodes. Figure 6 shows component placement with trace, ground plane and via locations. Include two vias near the GND pin of the LT1934 to help remove heat from the LT1934 to the ground plane. Hot Plugging Safely ...

Page 13

... AI.EI. 0.1 F 0.1 F Figure 7. A Well Chosen Input Network Prevents Input Voltage Overshoot and Ensures Reliable Operation When the LT1934 is Connected to a Live Supply aluminum electrolytic capacitor has been added. This capacitor’s high equivalent series resistance damps the circuit and eliminates the voltage overshoot. The extra ...

Page 14

... High Temperature Considerations The die temperature of the LT1934 must be lower than the maximum rating of 125 C. This is generally not a concern unless the ambient temperature is above 85 C. For higher temperatures, care should be taken in the layout of the circuit to ensure good heat sinking of the LT1934 ...

Page 15

... LT1934-1 10pF ON OFF SHDN FB GND C1: TAIYO YUDEN JMK316BJ226ML C2: TAIYO YUDEN GMK316BJ105ML D1: ZETEX ZHCS400 OR ON SEMI MBR0540 D2: CENTRAL CMPD914 L1: COILCRAFT DO1608C-154 OR WURTH ELECTRONICS WE-PD4 TYPE S LT1934/LT1934 100 H V OUT 3.3V 45mA 604k 1934 TA04 D2 L1 150 H V OUT ...

Page 16

... D2: CENTRAL CMPD914 L1: SUMIDA CR43-330 D3 + L1B 50 H • C1 L1A BOOST • LT1934-1 D4 10V 1 F SHDN FB 390k 715k GND D1: ON SEMICONDUCTOR MBR0540 D2, D3: BAT54 D4: CENTRAL CMPZ5240B L1: COILTRONICS CTX50-1 ZENER DIODE D4 PROVIDES AN UNDERVOLTAGE LOCKOUT, REDUCING THE INPUT CURRENT REQUIRED AT START- OUT 1 ...

Page 17

... V = 24V IN 400 300 V = 12V IN 200 100 0 3.5 2 4.5 BATTERY VOLTAGE (V) 1934 TA07b LT1934/LT1934-1 10k 0.047 CHRG GATE 0.022 F LTC4052 ACPR SENSE BAT 350mA TIMER GND 1-CELL 4.2V TIMER Li-Ion 0.1 F BATTERY 1934 TA07a CHARGE STATUS AC PRESENT 1934f ...

Page 18

... U TYPICAL APPLICATIO S 15V TO 32V ON OFF 18 12V Step-Down Converter D2 0 BOOST 100 2.2 F LT1934 D1 SHDN FB GND C1: KEMET T495D226K020AS C2: TAIYO YUDEN GMK325BJ225MN D1: ON SEMI MBR0540 D2, D4: CENTRAL CMPD914 D3: CENTRAL CMPZ5234B 6.2V ZENER L1: TDK SLF6028T-101MR42 D3 V OUT 12V 170mA 866k + ...

Page 19

... U S6 Package 6-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1636) 1.22 REF 1.50 – 1.75 2.80 BSC 1.4 MIN (NOTE 4) 0.95 BSC 0.80 – 0.90 1.00 MAX 0.09 – 0.20 (NOTE 3) LT1934/LT1934-1 2.90 BSC (NOTE 4) PIN ONE ID 0.30 – 0.45 6 PLCS (NOTE 3) 0.01 – 0.10 1.90 BSC S6 TSOT-23 0302 19 1934f ...

Page 20

... McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 5V Step-Down Converter 0.1 F BOOST 2.2 F LT1934 10pF SHDN FB GND C1: SANYO 6TPB68M C2: TAIYO YUDEN GMK325BJ225MN D1: ZETEX ZHCS400 OR ON SEMI MBR0540 D2: CENTRAL CMPD914 L1: SUMIDA CDRH5D28-680 COMMENTS V = 3.6V to 25V ThinSOT Package ...

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