TC1185-5 LDO VOLTAGE REGULATOR - Page 1
Forum section: electronics / projects

author: microic
author_rank: Newbie
timestamp: June 10, 2024, 07:24:55 am
content: Hi to all,Trying to design battery operated unit with ATTiny85 and 6V battery. Voltage regulator TC1185-5, I choose because I want to have 5V from battery, but when input is below 5V regulator just copy input to output. When Voltage on input is higher than 5 V output is regulated correctly. I use 1uF capacitors on both input and output. Already tried with two regulators, same result. I will appreciate any idea. Thanks, Damir

author: moffy
author_rank: Super Contributor
timestamp: June 10, 2024, 09:18:16 am
content: You could use something like a voltage monitoring circuit that at say 5.25V from the battery, bypasses the regulator with say a switched PMOS MOSFET in parallel with the regulator.

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 10, 2024, 09:42:05 am
content: I'm not exactly sure what's the question here. TC1185 is a CMOS LDO, and just like most CMOS LDO with P-channel pass element it does revert to bypass mode once input voltage drops below regulation. No need for external bypass.

author: xvr
author_rank: Frequent Contributor
timestamp: June 10, 2024, 10:03:14 am
content: Quote from: microic on June 10, 2024, 07:24:55 amFor LDO, like asanylinear regulator, physically impossible to raise up input voltage - it can only dissipate some of them on itself (this is the way as linear regulators work)QuoteUse switching mode regulator. You need some step up/step down regulator.https://www.digikey.ie/en/products/filter/dc-dc-switching-controllers/715?s=N4IgjCBcpmAMVQGMoDMCGAbAzgUwDQgD2UA2iACxwAcAzAGwKFV0CcEzNtrtInbCALqEADgBcoIAMpiATgEsAdgHMQAX0IAmAKzbEIFJAw4CxMiFrVWcMKz4WrcWhRDCQ4yTIUr1hWGE19Q2M8QhJIcnowBiYQKIYOcHorCl4-ZNZWantozU0KehzaTVobIoB2Ck1swnL6azhY6PL4ROb4QL9aFqd7CnLqcs07LThNAb1R6ooXKepGe00x60Kp9jTwFu1WVc3aaMnN%2Bm0KEaPtek7z8tjyk%2B6a8%2BpEu%2B04GZzyyqpPyvoNsADVK7QGscaPMDUGyscqLarlUpwwa6JF1RJ5QYtezPMAUbSPDHldiLOAnN4ky75Cn5K5LeqpVyiCSQaRyJSqDTgVgUbLQAxoLChMwRCw7Y6M9zM1neDl%2BLJ2PnBQWmcLkIScvKwIICkxhcwQNweFkAESIAFcAEaYXC%2BEAAWgVyCgcjNKv1rk5dsCiudsldepFekEag15mNAGEAPQRiWFPnyAAmkjtrXsRpA9jEAE8RDaWehsCgQ0AOr something ready made:https://www.digikey.ie/en/products/filter/dc-dc-converters/922?s=N4IgjCBcpgLA7BaIDGUBmBDANgZwKYA0IA9lANogBMVAHAKwAMsIAusQA4AuUIAylwBOASwB2AcxABfYmHpV6UUGkhY8RUhWqwAnGERtOPSPyFjJM8Dto6lqDDgLEykSozaWaYJMofrnWhDsINy8ACIkAK4ARtj40sQAtLbIKkKRGi6UQZaJVHZpghkBriCKrFKeWgAmKAD0tR5AA

author: microic
author_rank: Newbie
timestamp: June 10, 2024, 08:01:50 pm
content: Hi to all,thanks for answers,I am in doubt because in data sheet for TC1165-5 is listed Vin Max 6V, Vin MIN 2.7V, output 5V.I assume that output should be 5V in entire scale for Vin from 2.7 - 6V.there are also other type of same LDO series with different output Voltages , 1.8V,3.3V...they also mention that is for battery operated circuits.is there any one of you can suggest circuit from experience that is working for 5V output,cca 100mA. with connected 3V batteries in serie.Thanks.

author: xvr
author_rank: Frequent Contributor
timestamp: June 10, 2024, 08:10:48 pm
content: QuoteNo. See note 1 (for Vin parameter) after table:QuoteQuoteSwitching mode DC/DC only, not LDO.

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 10, 2024, 10:56:47 pm
content: Quote from: microic on June 10, 2024, 08:01:50 pmNah, LDO can only shave excess voltage. They can't just add voltage out of nowhere.Quote from: xvr on June 10, 2024, 10:03:14 amThat's the "proper" solution, but for this low current it's often simpler to boost to 6V (or 5.5V if you got good LDO) and then regulate down to 5V with LDO. Boost converter is much more common and cheaper than buck-boost, and you get bonus lower noise here.