TPS61200 — Low Input Voltage Synchronous Boost Converter with Down-Mode

Overview

The TPS61200 (packaged in 10-pin VSON TPS61200DRCT) is a low-input-voltage synchronous boost converter from Texas Instruments designed for single-cell alkaline, NiMH, or Li-Ion battery power supplies and energy harvesting systems.

It is capable of starting up into full load at an input voltage as low as $0.5\text{ V}$ , and once running, continues operating down to $0.3\text{ V}$ . Crucially, the TPS61200 features Down-Mode operation: if input voltage exceeds the output voltage setting, the converter automatically switches to a buck-like down-conversion mode to maintain regulation without pass-through voltage spikes.

Quick reference


Regulator Type	Synchronous Boost Converter with Down-Mode
Package	VSON-10 (DRC / $3\times3\text{ mm}$ Exposed Thermal Pad)
Input Voltage Range ( $V_{IN}$ )	$0.3\text{ V}$ to $5.5\text{ V}$ DC ( $0.5\text{ V}$ startup)
Output Voltage Range ( $V_{OUT}$ )	$1.8\text{ V}$ to $5.5\text{ V}$ DC (Adjustable) / Fixed 3.3V, 5.0V
Continuous Output Current ( $I_{OUT}$ )	Up to $600\text{ mA}$ at 3.3V (from 1.2V input)
Switching Frequency	$1.5\text{ MHz}$ fixed internal clock
Conversion Efficiency	Up to $90\%$
Special Features	Programmable Undervoltage Lockout (`UVLO`), $55\ \mu\text{A}$ quiescent current

Pinout (VSON-10 Package)

text

        ┌─────────────┐
   VAUX ─│ 1        10 │─ VOUT
   VOUT ─│ 2         9 │─ FB
      L ─│ 3    EP   8 │─ UVLO
    GND ─│ 4         7 │─ PS
    VIN ─│ 5         6 │─ EN
        └─────────────┘

Pin	Name	Description
1	`VAUX`	Auxiliary supply input for internal circuitry bootstrap cap
2	`VOUT`	Regulated DC output voltage output pin
3	`L` / `SW`	Switch node connection for external inductor
4	`GND`	Ground reference (connected to exposed pad underneath)
5	`VIN`	Low-voltage DC input power supply pin (+0.3V to +5.5V)
6	`EN`	Enable control input (>1.2V enables converter, <0.4V disables)
7	`PS`	Power Save mode control pin (GND = Power Save enable, VOUT = forced PWM)
8	`UVLO`	Programmable Undervoltage Lockout resistor input
9	`FB`	Voltage feedback sense input pin ( $500\text{mV}$ internal reference)
10	`VOUT`	Second regulated output connection pin

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Input Supply Voltage	$V_{IN}$	0.3	1.2 / 3.7	5.5	V	Operational input range
Minimum Startup Voltage	$V_{START}$	—	0.5	0.8	V	$I_{OUT} = 1\text{mA}$
Feedback Reference Voltage	$V_{FB}$	490	500	510	mV	$T_A = 25^\circ\text{C}$
Switch Current Limit	$I_{CL}$	1200	1500	1800	mA	Peak inductor current limit
High-Side Switch $R_{DS(ON)}$	$R_{DS(ON)H}$	—	0.4	—	$\Omega$	$V_{OUT} = 3.3\text{V}$
Low-Side Switch $R_{DS(ON)}$	$R_{DS(ON)L}$	—	0.3	—	$\Omega$	$V_{OUT} = 3.3\text{V}$
Switching Frequency	$f_{SW}$	1.2	1.5	1.8	MHz	Internal oscillator
Quiescent Current	$I_Q$	—	55	80	$\mu\text{A}$	Power Save mode enabled

Typical Application Circuit (Single AA Cell to 3.3V Output)

text

       +V_IN (0.9V - 1.5V Single AA Cell)
          │
       [Pin 5: VIN] ── [ 4.7µH Inductor ] ── [Pin 3: L] ──── TPS61200 ──── [Pin 2/10: VOUT] ─── +3.3V Output
          │                                                                      │
       [Pin 4: GND]                                                           [ R1 ]
          │                                                                      │
         GND ────────────────────────────────────────────────────────────────────┴─── [Pin 9: FB]
                                                                                 │
                                                                               [ R2 ]
                                                                                 │
                                                                                GND

$V_{OUT} = 500\text{mV} \times \left( 1 + \frac{R_1}{R_2} \right)$

Common mistakes

Omitting the auxiliary capacitor on VAUX: A $100\text{ nF}$ ceramic capacitor must be connected between VAUX (Pin 1) and GND to support low-voltage startup and internal gate drive bootstrap.
Improper UVLO resistor calculation: Leaving the UVLO pin floating defaults to a high lockout threshold. Tie UVLO directly to VIN if external undervoltage lockout tuning is not required.

Notes

Down-Mode Feature: Standard boost converters short $V_{IN}$ to $V_{OUT}$ via their body diode if $V_{IN} > V_{OUT}$ . The TPS61200's Down-Mode disconnects the body diode to maintain output voltage regulation.

Interface	DC Input, DC Output, Switch Node SW, VAUX, EN, UVLO
Package	VSON-10 (DRC / 3 x 3 mm)