NCP1400ASN33T1 — 100mA Micropower PFM Step-Up (Boost) DC-DC Converter (3.3V)

Overview

The NCP1400ASN33T1 (NCP1400A 3.3V) is a miniature micropower step-up (boost) DC-DC converter manufactured by onsemi. Housed in a compact 5-pin surface-mount TSOP-5 (SOT-23-5) package, it provides a regulated $+3.3\text{V}$ DC rail at up to $100\text{ mA}$ from low-voltage single-cell power sources.

Featuring an ultra-low startup voltage of just $0.8\text{V}$ (operating down to $0.2\text{V}$ once started), an idle quiescent current of only $19\ \mu\text{A}$ , and a pulse-frequency modulation (PFM) architecture switching up to $180\text{ kHz}$ , the NCP1400A requires only three external components: a miniature inductor, a Schottky diode, and input/output ceramic capacitors. It is widely used in wearable electronics, wireless sensors, electronic badges, and battery-powered gadgets running microcontrollers (such as ATtiny, PIC, or MSP430) from a single $1.5\text{V}$ AA/AAA alkaline battery, $1.2\text{V}$ NiMH cell, or $3.0\text{V}$ CR2032 coin cell.

Quick reference


Converter Topology	Micropower PFM Step-Up (Boost) DC-DC Converter
Package	TSOP-5 (5-pin SMD / SOT-23-5)
Output Voltage ( $V_{OUT}$ )	$+3.3\text{ V}$ DC fixed ( $\pm 2.5\%$ )
Startup Input Voltage ( $V_{START}$ )	$0.8\text{ V}$ typical ( $0.9\text{ V}$ max)
Operating Input Range ( $V_{IN}$ )	$0.8\text{ V}$ to $3.3\text{ V}$ DC ( $6.0\text{ V}$ absolute max)
Output Current ( $I_{OUT}$ )	Up to $100\text{ mA}$ ( $V_{IN} = 1.5\text{V}, V_{OUT} = 3.3\text{V}$ )
Quiescent Current ( $I_Q$ )	$19\ \mu\text{A}$ typical (No load) / $< 0.1\ \mu\text{A}$ in shutdown
Switching Frequency	Up to $180\text{ kHz}$ (PFM architecture)
Peak Efficiency	Up to $82\%$
Shutdown Control	Active-HIGH Chip Enable (`CE`) pin

Pinout (TSOP-5 / SOT-23-5 Package)

text

        ┌───┬───┐
      1 │   │ 5 │ LX (Inductor Switching Node)
     CE │   └───┤
    OUT │ 2   4 │ GND (0V)
     NC │ 3     │
        └───┴───┘

Pin	Name	Type	Description
1	`CE`	Control Input	Chip Enable (Active HIGH; tie to $V_{IN}$ to enable, pull LOW for $< 0.1\ \mu\text{A}$ shutdown)
2	`OUT`	Power Output / Feedback	Output voltage sense and internal bias supply ( $+3.3\text{ V}$ )
3	`NC`	No Connect	Leave unconnected or solder to ground plane
4	`GND`	Ground	Common system ground reference ( $0\text{ V}$ )
5	`LX`	Switching Node	Drain of internal N-channel power MOSFET (Connect to inductor and Schottky diode anode)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Output Voltage	$V_{OUT}$	3.218	3.300	3.382	V	$I_O = 10\text{mA}, V_{IN} = 1.5\text{V}$
Minimum Startup Voltage	$V_{START}$	—	0.8	0.9	V	$I_O = 1.0\text{mA}$
Operating Voltage (Post Start)	$V_{HOLD}$	0.2	0.6	—	V	$I_O = 1.0\text{mA}$
Quiescent Current	$I_Q$	—	19.0	35.0	µA	$I_O = 0\text{mA}, V_{IN} = 1.5\text{V}$
Shutdown Current	$I_{SD}$	—	0.1	0.6	µA	$V_{CE} = 0\text{V}, V_{IN} = 1.5\text{V}$
Max Switching Frequency	$f_{OSC}$	140	180	220	kHz	$V_{OUT} = 3.3\text{V}$
Internal Switch Limit	$I_{LIM}$	—	350	—	mA	Peak inductor current

Typical Application Circuit

text

  Single Alkaline / NiMH Cell (0.9V - 1.5V)
           │
           ├───[ C_IN: 10µF Ceramic / Tantalum ]──┐
           │                                      │
           ├───[ L1: 47µH Inductor (CD54/0630) ]──┼───────────┐
           │                                      │           │
           │                                  [Pin 4: GND]    │
           │                                      │           │
       [Pin 1: CE]                                │       [Pin 5: LX]
         NCP1400A                                 │           │
       [Pin 2: OUT] ──────────────┬───────────────┴─── GND    │
           │                      │                           │
           │            [ D1: MBR0520LT1 Schottky ] ──────────┘
           │                      │ (Cathode to OUT)
           ├───[ C_OUT: 22µF Low-ESR Ceramic / Tantalum ]── GND
           │
  Regulated +3.3V DC (Up to 100mA for Microcontroller & Radio)

Recommended External Components

Inductor ( $L_1$ ): $22\ \mu\text{H}$ to $47\ \mu\text{H}$ shielded power inductor with saturation current $I_{SAT} \ge 500\text{ mA}$ and low DC resistance (e.g. Sumida CD43 / CD54).
Schottky Diode ( $D_1$ ): Low forward drop Schottky diode (e.g. MBR0520L, 1N5819HW, BAT54).
Output Capacitor ( $C_{OUT}$ ): $10\ \mu\text{F} \dots 22\ \mu\text{F}$ low-ESR X5R/X7R ceramic or tantalum capacitor placed directly adjacent to Pins 2 and 4.

Common mistakes

Using a standard PN junction diode instead of Schottky: Standard silicon diodes (e.g. 1N4148, 1N4007) have a $0.7\text{V} \dots 1.0\text{V}$ forward drop, severely cutting efficiency and preventing the circuit from boosting under load. Always use a Schottky diode with $V_F < 0.35\text{V}$ .
Input voltage exceeding output voltage: In boost topology, current flows directly from input through inductor and diode to output. If $V_{IN} > V_{OUT}$ (e.g. connecting a 4.2V LiPo battery to a 3.3V NCP1400A), the output voltage will rise uncontrollably to $V_{IN} - V_{DIODE}$ .

Notes

Suffix Guide: ASN33 designates $+3.3\text{V}$ fixed output; ASN50 designates $+5.0\text{V}$ fixed output; T1G denotes RoHS lead-free tape & reel packaging.

Interface	5-Pin SMD (CE, OUT, NC, GND, LX)
Package	5-pin TSOP (TSOP-5 / SOT-23-5)