Skip to main content

Honest Reviews: FAN53202 - Fairchild Semiconductor's Programmable TinyBuck Regulator


While browsing through the latest ICs released in the market by major semiconductor manufacturers, I came across this cute little buck regulator by Fairchild Semiconductor. I really don't do written reviews (because it kind of feels like I'm advertising the company's product) but I'll make this one an exception. I mean, how can I just ignore this teenie weenie monster of an IC (I'll explain why I see it as a monster later) that I just came across with.


FAN53202 or TinyBuck (mind if I call it by its family name for the rest of the article) is "a highly efficient step-down switching voltage regulator that offers best-in-class load transient and a programmable output voltage" according to FS. Now, the terms "highly efficient" and "best-in-class" are highly arbitrary marketing terms (that sometimes vexes me a lot, really, because engineers don't make comparisons on a whim without reference points). Plus, I didn't want to believe that TinyBuck, which is 1.6mm by 2mm in size, could offer superior efficiency and load transient characteristics as compared to its competitors so easily, so I took a closer look at its data sheet (link available below).
Download TinyBuck's DataSheet


DataSheet Analysis

Based on the data sheet, the input voltage range is from 2.5V to 5.5V, which is typical. TinyBuck is programmable through an SPI or I2C interface that can operate up to 3.4 MHz. There is an internal soft-start to avoid shocking sensitive internal circuitry with a sudden VIN transient, undervoltage lock-out (UVLO - I'm guessing around 2.5V-2.9V), TSD of 150 degrees Celsius (a little lower than ordinary), and SCP protection. The default frequency is 2.4MHz and VOUT is trimmable from -0.6 to 1.3875V in 12.5 mV steps. It is claiming a "Best-in-Class" load transient again (ugh, I'll dig deeper into this) and a continuous output current ability of 5A (wow). The quiescent current is 60uA in PFM mode, a little higher than expected. Finally, a 91% efficiency (I'm guessing this is the maximum achieved efficiency by TinyBuck because the efficiency curves are different for different modes of operation. All of this is crammed in a 1.6mm. by 2mm. wafer-level chip scale package ( so tiny <3 , I hope I don't accidentally inhale this thing).

Now it is time to digest. Shown below is the block diagram and pin configuration of TinyBuck.
Figure 1. Block diagram of FAN53202



Figure 2. Pin configuration of FAN53202

To power up TinyBuck, we set EN to high, bias VIN with 3.6V [the datasheet didn't really indicate a typical voltage but I'm pretty sure it will operate correctly at 3.6V], set my I2C slave address to C0
and off we go. From the register map, by sending 01h/00h to 01h/3Fh, I should be able to trim VOUT.

It looks like the modes are up to date (they've integrated the Auto and PFM modes). Oh, and the slew rate is adjustable.

So on the testbench, when I probe the SW pin, I'm expecting a 2.4 MHz switching frequency to appear on my scope. The power up sequence should go smoothly.

Highly Efficient, just like a typical switching regulator ought to be

Figure 3. Efficiency curves for FAN53202

 From the efficiency curves, TinyBuck was obviously evaluated in Auto/PFM mode (Remember that PWM mode is inefficient at low loads, and the hump near the end of the curve accounts for the transition from PFM to PWM - i.e. Auto mode). TinyBuck indeed has a maximum efficiency of 91%, but don't expect it to be 91% efficient at a range of 1 mA to 10 mA load.

The "...continuous output current ability of 5A" - Wow!

In order to analyze the claim that TinyBuck can indeed withstand 5A of continuous load, I've extracted the load regulation curves of the chip.
Below are the load regulation curves of TinyBuck.

Figure 4. Load regulation curves of FAN53202
What does this indicate? Based from the curves, TinyBuck can take up to 5A of current or more before shutting down. This signifies that you can load VOUT with something greater than 5A and still expect an undamaged TinyBuck! (I assume the trend is dipping too much a little further than the 5A point, though there are times when switching regulators would just suddenly turn off)


"Best-in-Class" Load Transient Response, pretty much looks like it

 Finally, I review the transient response of TinyBuck, which looks very promising. Below is the transient response of TinyBuck.
Figure 5. Transient response of FAN53202. Probably measured with a Tektronix MSO.

 A pulsed load of 1A to 1.5A would typically yield a voltage deviation of around 200mV or more. But from the scope measurement (mind you, I think a Tektronix MSOXXXX series was used XD Hahaha... one of my favorite scopes by the way, I have to write all about it in another article...) the voltage only changed by around 30-50mV!! Amazing! If you get a typical statistic of load transients of switching regulators, you'd get 30-50mV at loads of 10-100mA with 1uA rise time and fall time.

But wait, looking at the right side of the CH1 label. The channel is bandwidth limited? Well, I'm not really sure if band-limiting the voltage probe would have a BIG effect on the transient response but I'm sure there is, though quite negligible (in the order of a few mV perhaps).

 In the end, TinyBuck does live up to its claims, based on current standards. I would like to see more reviews of TinyBuck by actual commercial users in the future.



Comments

Popular posts from this blog

Calculator Techniques for the Casio FX-991ES and FX-991EX Unraveled

In solving engineering problems, one may not have the luxury of time. Most situations demand immediate results. The price of falling behind schedule is costly and demeaning to one's reputation. Therefore, every bit of precaution must be taken to expedite calculations. The following introduces methods to tackle these problems speedily using a Casio calculator FX-991ES and FX-991EX.


►For algebraic problems where you need to find the exact value of a dependent or independent variable, just use the CALC or [ES] Mode 5 functions or [EX] MENU A functions.


►For definite differentiation and integration problems, simply use the d/dx and integral operators in the COMP mode.


►For models that follow the differential equation: dP/dx=kt and models that follow a geometric function(i.e. A*B^x).

[ES]
-Simply go to Mode 3 (STAT) (5)      e^x
-For geometric functions Mode 3 (STAT) 6 A*B^x
-(Why? Because the solution to the D.E. dP/dx=kt is an exponential function e^x.
When we know the boundary con…

Yay or Nay? A Closer Look at AnDapt’s PMIC On-Demand Technology

Innovations on making product features customizable are recently gaining popularity. Take Andapt for example, a fabless start-up that unveiled its Multi-Rail Power Platform technology for On-Demand PMIC applications a few months back. (read all about it here: Will PMIC On-Demand Replace Catalog Power Devices?) Their online platform, WebAmp, enables the consumer to configure the PMIC based on desired specifications. Fortunately, I got a hands-on experience during the trial period (without the physical board (AmP8DB1) or adaptor (AmpLink)). In my opinion, their GUI is friendly but it lacks a verification method for tuning (i.e. the entered combination of specs). How would we know if it will perform as expected or if there are contradicting indications that yield queer behavior? Also, there is not just one IP available, but many that cater to a differing number of channels and voltage requirements (each with their own price tag).
Every new emerging technology has the potential to oversh…

Common Difficulties and Mishaps in 6.004 Computation Structures (by MITx)

Updated: 
May 6, 2018
VLSI Project: The Beta Layout [help needed]Current Tasks: ►Complete 32-bit ALU layout [unpipelined] in a 3-metal-layer C5 process. ►Extend Excel VBA macro to generate code for sequential instructions (machine language to actual electrical signals).
Current Obstacles/Unresolved Decisions:
►Use of complementary CMOS or pass transistor logic (do both? time expensive, will depend on sched.
►Adder selection: Brent-Kung; Kogge Stone; Ladner Fischer (brent takes up most space but seems to be fastest, consider fan-out) [do all? time expensive, will depend on sched.)
►layout requirements and DRC errors

Please leave a comment on the post below for advise. Any help is highly appreciated.